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Dimet-Wiley AL, Latham CM, Brightwell CR, Neelakantan H, Keeble AR, Thomas NT, Noehren H, Fry CS, Watowich SJ. Nicotinamide N-methyltransferase inhibition mimics and boosts exercise-mediated improvements in muscle function in aged mice. Sci Rep 2024; 14:15554. [PMID: 38969654 PMCID: PMC11226645 DOI: 10.1038/s41598-024-66034-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Accepted: 06/26/2024] [Indexed: 07/07/2024] Open
Abstract
Human hallmarks of sarcopenia include muscle weakness and a blunted response to exercise. Nicotinamide N-methyltransferase inhibitors (NNMTis) increase strength and promote the regenerative capacity of aged muscle, thus offering a promising treatment for sarcopenia. Since human hallmarks of sarcopenia are recapitulated in aged (24-month-old) mice, we treated mice from 22 to 24 months of age with NNMTi, intensive exercise, or a combination of both, and compared skeletal muscle adaptations, including grip strength, longitudinal running capacity, plantarflexor peak torque, fatigue, and muscle mass, fiber type, cross-sectional area, and intramyocellular lipid (IMCL) content. Exhaustive proteome and metabolome analyses were completed to identify the molecular mechanisms underlying the measured changes in skeletal muscle pathophysiology. Remarkably, NNMTi-treated aged sedentary mice showed ~ 40% greater grip strength than sedentary controls, while aged exercised mice only showed a 20% increase relative to controls. Importantly, the grip strength improvements resulting from NNMTi treatment and exercise were additive, with NNMTi-treated exercised mice developing a 60% increase in grip strength relative to sedentary controls. NNMTi treatment also promoted quantifiable improvements in IMCL content and, in combination with exercise, significantly increased gastrocnemius fiber CSA. Detailed skeletal muscle proteome and metabolome analyses revealed unique molecular mechanisms associated with NNMTi treatment and distinct molecular mechanisms and cellular processes arising from a combination of NNMTi and exercise relative to those given a single intervention. These studies suggest that NNMTi-based drugs, either alone or combined with exercise, will be beneficial in treating sarcopenia and a wide range of age-related myopathies.
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Affiliation(s)
| | - Christine M Latham
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, USA
| | - Camille R Brightwell
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, USA
| | | | - Alexander R Keeble
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, USA
| | - Nicholas T Thomas
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, USA
| | - Haley Noehren
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, USA
| | - Christopher S Fry
- Center for Muscle Biology, College of Health Sciences, University of Kentucky, Lexington, KY, USA
| | - Stanley J Watowich
- Department of Biochemistry and Molecular Biology, University of Texas Medical Branch, Galveston, TX, USA.
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Ramos SV, Distefano G, Lui LY, Cawthon PM, Kramer P, Sipula IJ, Bello FM, Mau T, Jurczak MJ, Molina AJ, Kershaw EE, Marcinek DJ, Shankland E, Toledo FG, Newman AB, Hepple RT, Kritchevsky SB, Goodpaster BH, Cummings SR, Coen PM. Role of Cardiorespiratory Fitness and Mitochondrial Oxidative Capacity in Reduced Walk Speed of Older Adults With Diabetes. Diabetes 2024; 73:1048-1057. [PMID: 38551899 PMCID: PMC11189829 DOI: 10.2337/db23-0827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 03/26/2024] [Indexed: 04/09/2024]
Abstract
Cardiorespiratory fitness and mitochondrial oxidative capacity are associated with reduced walking speed in older adults, but their impact on walking speed in older adults with diabetes has not been clearly defined. We examined differences in cardiorespiratory fitness and skeletal muscle mitochondrial oxidative capacity between older adults with and without diabetes, as well as determined their relative contribution to slower walking speed in older adults with diabetes. Participants with diabetes (n = 159) had lower cardiorespiratory fitness and mitochondrial respiration in permeabilized fiber bundles compared with those without diabetes (n = 717), following adjustments for covariates including BMI, chronic comorbid health conditions, and physical activity. Four-meter and 400-m walking speeds were slower in those with diabetes. Mitochondrial oxidative capacity alone or combined with cardiorespiratory fitness mediated ∼20-70% of the difference in walking speed between older adults with and without diabetes. Additional adjustments for BMI and comorbidities further explained the group differences in walking speed. Cardiorespiratory fitness and skeletal muscle mitochondrial oxidative capacity contribute to slower walking speeds in older adults with diabetes. ARTICLE HIGHLIGHTS
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Affiliation(s)
| | | | - Li-Yung Lui
- San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco, CA
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA
| | - Peggy M. Cawthon
- San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco, CA
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA
| | - Philip Kramer
- Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC
| | - Ian J. Sipula
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Fiona M. Bello
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Theresa Mau
- San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco, CA
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA
| | - Michael J. Jurczak
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Anthony J. Molina
- Department of Medicine, University of California, San Diego, La Jolla, CA
| | - Erin E. Kershaw
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - David J. Marcinek
- Department of Radiology, University of Washington School of Medicine, Seattle, WA
| | - Eric Shankland
- Department of Radiology, University of Washington School of Medicine, Seattle, WA
| | - Frederico G.S. Toledo
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Anne B. Newman
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Russell T. Hepple
- Department of Physical Therapy, University of Florida, Gainesville, FL
| | - Stephen B. Kritchevsky
- Department of Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, NC
| | | | - Steven R. Cummings
- San Francisco Coordinating Center, California Pacific Medical Center Research Institute, San Francisco, CA
- Department of Epidemiology and Biostatistics, University of California, San Francisco, San Francisco, CA
| | - Paul M. Coen
- Translational Research Institute, AdventHealth, Orlando, FL
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Min SH, Kang GM, Park JW, Kim MS. Beneficial Effects of Low-Grade Mitochondrial Stress on Metabolic Diseases and Aging. Yonsei Med J 2024; 65:55-69. [PMID: 38288646 PMCID: PMC10827639 DOI: 10.3349/ymj.2023.0131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 11/07/2023] [Accepted: 12/04/2023] [Indexed: 02/01/2024] Open
Abstract
Mitochondria function as platforms for bioenergetics, nutrient metabolism, intracellular signaling, innate immunity regulators, and modulators of stem cell activity. Thus, the decline in mitochondrial functions causes or correlates with diabetes mellitus and many aging-related diseases. Upon stress or damage, the mitochondria elicit a series of adaptive responses to overcome stress and restore their structural integrity and functional homeostasis. These adaptive responses to low-level or transient mitochondrial stress promote health and resilience to upcoming stress. Beneficial effects of low-grade mitochondrial stress, termed mitohormesis, have been observed in various organisms, including mammals. Accumulated evidence indicates that treatments boosting mitohormesis have therapeutic potential in various human diseases accompanied by mitochondrial stress. Here, we review multiple cellular signaling pathways and interorgan communication mechanisms through which mitochondrial stress leads to advantageous outcomes. We also discuss the relevance of mitohormesis in obesity, diabetes, metabolic liver disease, aging, and exercise.
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Affiliation(s)
- Se Hee Min
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Diabetes Center, Asan Medical Center and University of Ulsan College of Medicine, Seoul, Korea
- Appetite Regulation Laboratory, Asan Institute for Life Science, Seoul, Korea
| | - Gil Myoung Kang
- Appetite Regulation Laboratory, Asan Institute for Life Science, Seoul, Korea
| | - Jae Woo Park
- Appetite Regulation Laboratory, Asan Institute for Life Science, Seoul, Korea
| | - Min-Seon Kim
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Diabetes Center, Asan Medical Center and University of Ulsan College of Medicine, Seoul, Korea
- Appetite Regulation Laboratory, Asan Institute for Life Science, Seoul, Korea.
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4
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Ramos SV, Distefano G, Lui LY, Cawthon PM, Kramer P, Sipula IJ, Bello FM, Mau T, Jurczak MJ, Molina AJ, Kershaw EE, Marcinek DJ, Toledo FGS, Newman AB, Hepple RT, Kritchevsky SB, Goodpaster BH, Cummings SR, Coen PM. Role of Cardiorespiratory Fitness and Mitochondrial Energetics in Reduced Walk Speed of Older Adults with Diabetes in the Study of Muscle, Mobility and Aging (SOMMA). MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.11.03.23297992. [PMID: 37986814 PMCID: PMC10659460 DOI: 10.1101/2023.11.03.23297992] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
Rationale Cardiorespiratory fitness and mitochondrial energetics are associated with reduced walking speed in older adults. The impact of cardiorespiratory fitness and mitochondrial energetics on walking speed in older adults with diabetes has not been clearly defined. Objective To examine differences in cardiorespiratory fitness and skeletal muscle mitochondrial energetics between older adults with and without diabetes. We also assessed the contribution of cardiorespiratory fitness and skeletal muscle mitochondrial energetics to slower walking speed in older adults with diabetes. Findings Participants with diabetes had lower cardiorespiratory fitness and mitochondrial energetics when compared to those without diabetes, following adjustments for covariates including BMI, chronic comorbid health conditions, and physical activity. 4-m and 400-m walking speeds were slower in those with diabetes. Mitochondrial oxidative capacity alone or combined with cardiorespiratory fitness mediated ∼20-70% of the difference in walk speed between older adults with and without diabetes. Further adjustments of BMI and co-morbidities further explained the group differences in walk speed. Conclusions Skeletal muscle mitochondrial energetics and cardiorespiratory fitness contribute to slower walking speeds in older adults with diabetes. Cardiorespiratory fitness and mitochondrial energetics may be therapeutic targets to maintain or improve mobility in older adults with diabetes. ARTICLE HIGHLIGHTS Why did we undertake this study? To determine if mitochondrial energetics and cardiorespiratory fitness contribute to slower walking speed in older adults with diabetes. What is the specific question(s) we wanted to answer? Are mitochondrial energetics and cardiorespiratory fitness in older adults with diabetes lower than those without diabetes? How does mitochondrial energetics and cardiorespiratory fitness impact walking speed in older adults with diabetes? What did we find? Mitochondrial energetics and cardiorespiratory fitness were lower in older adults with diabetes compared to those without diabetes, and energetics, and cardiorespiratory fitness, contributed to slower walking speed in those with diabetes. What are the implications of our findings? Cardiorespiratory fitness and mitochondrial energetics may be key therapeutic targets to maintain or improve mobility in older adults with diabetes.
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Schleh MW, Ahn C, Ryan BJ, Chugh OK, Luker AT, Luker KE, Gillen JB, Ludzki AC, Van Pelt DW, Pitchford LM, Zhang T, Rode T, Howton SM, Burant CF, Horowitz JF. Both moderate- and high-intensity exercise training increase intramyocellular lipid droplet abundance and modify myocellular distribution in adults with obesity. Am J Physiol Endocrinol Metab 2023; 325:E466-E479. [PMID: 37729021 PMCID: PMC10864005 DOI: 10.1152/ajpendo.00093.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 09/12/2023] [Accepted: 09/12/2023] [Indexed: 09/22/2023]
Abstract
Exercise training modifies lipid metabolism in skeletal muscle, but the effect of exercise training on intramyocellular lipid droplet (LD) abundance, size, and intracellular distribution in adults with obesity remains elusive. This study compared high-intensity interval training (HIIT) with more conventional moderate-intensity continuous training (MICT) on intramyocellular lipid content, as well as LD characteristics (size and number) and abundance within the intramyofibrillar (IMF) and subsarcolemmal (SS) regions of type I and type II skeletal muscle fibers in adults with obesity. Thirty-six adults with obesity [body mass index (BMI) = 33 ± 3 kg/m2] completed 12 wk (4 days/wk) of either HIIT (10 × 1 min, 90% HRmax + 1-min active recovery; n = 19) or MICT (45-min steady-state exercise, 70% HRmax; n = 17), while on a weight-maintaining diet throughout training. Skeletal muscle biopsies were collected from the vastus lateralis before and after training, and intramyocellular lipid content and intracellular LD distribution were measured by immunofluorescence microscopy. Both MICT and HIIT increased total intramyocellular lipid content by more than 50% (P < 0.01), which was attributed to a greater LD number per µm2 in the IMF region of both type I and type II muscle fibers (P < 0.01). Our findings also suggest that LD lipophagy (autophagy-mediated LD degradation) may be transiently upregulated the day after the last exercise training session (P < 0.02 for both MICT and HIIT). In summary, exercise programs for adults with obesity involving either MICT or HIIT increased skeletal muscle LD abundance via a greater number of LDs in the IMF region of the myocyte, thereby providing more lipid in close proximity to the site of energy production during exercise.NEW & NOTEWORTHY In this study, 12 wk of either moderate-intensity continuous training (MICT) or high-intensity interval training (HIIT) enhanced skeletal muscle lipid abundance by increasing lipid droplet number within the intramyofibrillar (IMF) region of muscle. Because the IMF associates with high energy production during muscle contraction, this adaptation may enhance lipid oxidation during exercise. Despite differences in training intensity and energy expenditure between MICT and HIIT, their effects on muscle lipid abundance and metabolism were remarkably similar.
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Affiliation(s)
- Michael W Schleh
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Cheehoon Ahn
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Benjamin J Ryan
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Olivia K Chugh
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Austin T Luker
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Kathryn E Luker
- Department of Radiology, Center for Molecular Imaging, University of Michigan, Ann Arbor, Michigan, United States
- Biointerfaces Institute, University of Michigan, Ann Arbor, Michigan, United States
| | - Jenna B Gillen
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Alison C Ludzki
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Douglas W Van Pelt
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Lisa M Pitchford
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Tao Zhang
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Thomas Rode
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Suzette M Howton
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Charles F Burant
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, United States
| | - Jeffrey F Horowitz
- Substrate Metabolism Laboratory, School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
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6
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Hinkley JM, Yu G, Standley RA, Distefano G, Tolstikov V, Narain NR, Greenwood BP, Karmacharya S, Kiebish MA, Carnero EA, Yi F, Vega RB, Goodpaster BH, Gardell SJ, Coen PM. Exercise and ageing impact the kynurenine/tryptophan pathway and acylcarnitine metabolite pools in skeletal muscle of older adults. J Physiol 2023; 601:2165-2188. [PMID: 36814134 PMCID: PMC10278663 DOI: 10.1113/jp284142] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 02/14/2023] [Indexed: 02/24/2023] Open
Abstract
Exercise-induced perturbation of skeletal muscle metabolites is a probable mediator of long-term health benefits in older adults. Although specific metabolites have been identified to be impacted by age, physical activity and exercise, the depth of coverage of the muscle metabolome is still limited. Here, we investigated resting and exercise-induced metabolite distribution in muscle from well-phenotyped older adults who were active or sedentary, and a group of active young adults. Percutaneous biopsies of the vastus lateralis were obtained before, immediately after and 3 h following a bout of endurance cycling. Metabolite profile in muscle biopsies was determined by tandem mass spectrometry. Mitochondrial energetics in permeabilized fibre bundles was assessed by high resolution respirometry and fibre type proportion was assessed by immunohistology. We found that metabolites of the kynurenine/tryptophan pathway were impacted by age and activity. Specifically, kynurenine was elevated in muscle from older adults, whereas downstream metabolites of kynurenine (kynurenic acid and NAD+ ) were elevated in muscle from active adults and associated with cardiorespiratory fitness and muscle oxidative capacity. Acylcarnitines, a potential marker of impaired metabolic health, were elevated in muscle from physically active participants. Surprisingly, despite baseline group difference, acute exercise-induced alterations in whole-body substrate utilization, as well as muscle acylcarnitines and ketone bodies, were remarkably similar between groups. Our data identified novel muscle metabolite signatures that associate with the healthy ageing phenotype provoked by physical activity and reveal that the metabolic responsiveness of muscle to acute endurance exercise is retained [NB]:AUTHOR: Please ensure that the appropriate material has been provide for Table S2, as well as for Figures S1 to S7, as also cited in the text with age regardless of activity levels. KEY POINTS: Kynurenine/tryptophan pathway metabolites were impacted by age and physical activity in human muscle, with kynurenine elevated in older muscle, whereas downstream products kynurenic acid and NAD+ were elevated in exercise-trained muscle regardless of age. Acylcarnitines, a marker of impaired metabolic health when heightened in circulation, were elevated in exercise-trained muscle of young and older adults, suggesting that muscle act as a metabolic sink to reduce the circulating acylcarnitines observed with unhealthy ageing. Despite the phenotypic differences, the exercise-induced response of various muscle metabolite pools, including acylcarnitine and ketone bodies, was similar amongst the groups, suggesting that older adults can achieve the metabolic benefits of exercise seen in young counterparts.
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Affiliation(s)
- J. Matthew Hinkley
- AdventHealth Translational Research Institute, AdventHealth Orlando, Orlando, FL, 32804, USA
| | - GongXin Yu
- AdventHealth Translational Research Institute, AdventHealth Orlando, Orlando, FL, 32804, USA
| | - Robert A. Standley
- AdventHealth Translational Research Institute, AdventHealth Orlando, Orlando, FL, 32804, USA
| | - Giovanna Distefano
- AdventHealth Translational Research Institute, AdventHealth Orlando, Orlando, FL, 32804, USA
| | | | | | | | | | | | - Elvis Alvarez Carnero
- AdventHealth Translational Research Institute, AdventHealth Orlando, Orlando, FL, 32804, USA
| | - Fanchao Yi
- AdventHealth Translational Research Institute, AdventHealth Orlando, Orlando, FL, 32804, USA
| | - Rick B. Vega
- AdventHealth Translational Research Institute, AdventHealth Orlando, Orlando, FL, 32804, USA
| | - Bret H. Goodpaster
- AdventHealth Translational Research Institute, AdventHealth Orlando, Orlando, FL, 32804, USA
| | - Stephen J. Gardell
- AdventHealth Translational Research Institute, AdventHealth Orlando, Orlando, FL, 32804, USA
| | - Paul M. Coen
- AdventHealth Translational Research Institute, AdventHealth Orlando, Orlando, FL, 32804, USA
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7
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Abstract
Ischemic heart disease and stroke are the number 1 and number 2 causes of death worldwide, respectively. A lifelong commitment to exercise reduces the risk of these adverse events and is also associated with several cardiometabolic improvements, including reductions in blood pressure, cholesterol, and inflammatory markers, as well as improved glucose control. Routine exercise also reduces the risk of developing comorbidities that increase the risk of cardiovascular or cerebrovascular disease. While the benefits of a lifelong commitment to exercise are well documented, there is a complex interaction between exercise and stroke risk, such that the risk of ischemic or hemorrhagic stroke may increase acutely during or immediately following exercise. In this article, we discuss the physiological responses to different types of exercise, as well as the determinants of resting and exertional cerebrovascular perfusion, and explore the complex interaction between atrial fibrillation, exercise, and stroke risk. Finally, we highlight the increased risk of stroke during different types of exercise, as well as factors that may alleviate this risk.
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Affiliation(s)
- Justin A Edward
- Department of Medicine-Cardiology, University of Colorado Anschutz Medical Campus, Aurora. (J.A.E., W.K.C.)
| | - William K Cornwell
- Department of Medicine-Cardiology, University of Colorado Anschutz Medical Campus, Aurora. (J.A.E., W.K.C.).,Clinical Translational Research Center, University of Colorado Anschutz Medical Campus, Aurora. (W.K.C.)
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8
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Barrett JS, Whytock KL, Strauss JA, Wagenmakers AJM, Shepherd SO. High intramuscular triglyceride turnover rates and the link to insulin sensitivity: influence of obesity, type 2 diabetes and physical activity. Appl Physiol Nutr Metab 2022; 47:343-356. [PMID: 35061523 DOI: 10.1139/apnm-2021-0631] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Large intramuscular triglyceride (IMTG) stores in sedentary, obese individuals have been linked to insulin resistance, yet well-trained athletes exhibit high IMTG levels whilst maintaining insulin sensitivity. Contrary to previous assumptions, it is now known that IMTG content per se does not result in insulin resistance. Rather, insulin resistance is caused, at least in part, by the presence of high concentrations of harmful lipid metabolites, such as diacylglycerols and ceramides in muscle. Several mechanistic differences between obese sedentary individuals and their highly trained counterparts have been identified, which determine the differential capacity for IMTG synthesis and breakdown in these populations. In this review, we first describe the most up-to-date mechanisms by which a low IMTG turnover rate (both breakdown and synthesis) leads to the accumulation of lipid metabolites and results in skeletal muscle insulin resistance. We then explore current and potential exercise and nutritional strategies that target IMTG turnover in sedentary obese individuals, to improve insulin sensitivity. Overall, improving IMTG turnover should be an important component of successful interventions that aim to prevent the development of insulin resistance in the ever-expanding sedentary, overweight and obese populations. Novelty: A description of the most up-to-date mechanisms regulating turnover of the IMTG pool. An exploration of current and potential exercise/nutritional strategies to target and enhance IMTG turnover in obese individuals. Overall, highlights the importance of improving IMTG turnover to prevent the development of insulin resistance.
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Affiliation(s)
- J S Barrett
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - K L Whytock
- Translational Research Institute, AdventHealth, Orlando, FL 32804, USA
| | - J A Strauss
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - A J M Wagenmakers
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
| | - S O Shepherd
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, UK
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9
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Cabre HE, Greenwalt CE, Gould LM, Hirsch KR, Blue MNM, Smith-Ryan AE. Exploring the "Athlete's Paradox": Division I Cross-Country Runners Demonstrate Similar Muscle Characteristics to Recreationally Trained Young Adults. J Strength Cond Res 2021; 35:3213-3217. [PMID: 34474434 DOI: 10.1519/jsc.0000000000004127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
ABSTRACT Cabre, HE, Greenwalt, CE, Gould, LM, Hirsch, KR, Blue, MNM, and Smith-Ryan, AE. Exploring the "Athlete's Paradox": Division I cross-country runners demonstrate similar muscle characteristics to recreationally trained young adults. J Strength Cond Res XX(X): 000-000, 2021-Endurance training can influence body composition and muscle characteristics. Endurance athletes have demonstrated elevated intramuscular fat (IMF), yet individuals with greater body fat also demonstrate elevated IMF. The purpose of this study was to examine differences in muscle characteristics (echo intensity [EI] and muscle cross-sectional area [mCSA]) and body composition between Division I collegiate athletes and college-age adults matched for percent fat (%fat). Thirty cross-country athletes (XC) and 30 normal-weight (NW) recreationally active college students (male athletes: n = 30; female athletes: n = 30; mean ± SD: age: 19.2 ± 1.1 years; body mass: 61.7 ± 8.7 kg; %fat: 18.0 ± 5.2%) underwent a panoramic ultrasound scan of the vastus lateralis to evaluate EI and mCSA. A full-body dual-energy x-ray absorptiometry scan was used to assess fat mass (FM), lean mass (LM), and %fat. Independent t-tests were used to evaluate mCSA, EI, and body composition. Significance level was set at ≤ 0.05. There were no significant differences between the XC and NW cohorts in mCSA (mean difference [MD; XC - NW], -1.30 ± -0.40 cm3; p = 0.340) or EI (MD: 3.97 ± 2.66 a.u.; p = 0.478). Body composition was not different between the groups: FM (MD: -0.14 ± -0.54 kg; p = 0.848), LM (-3.07 ± 1.25 kg; p = 0.268), or bone mineral content (-0.21 ± 0.03 kg; p = 0.120). There were also no significant differences for any outcome variables when stratified by male athletes (p = 0.097-0.468) or female athletes (p = 0.055-0.700). These results suggest that XC athletes may have similar muscle characteristics to NW individuals when matched for %fat. Understanding and tracking muscle characteristics in XC athletes may be important for performance, injury prevention, and the transition to retirement.
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Affiliation(s)
- Hannah E Cabre
- Applied Physiology Laboratory, Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, North Carolina; Human Movement Science Curriculum, Department of Allied Health Science, University of North Carolina, Chapel Hill, North Carolina; Institute of Sport Science Medicine, Department of Nutrition, Food, and Exercise Science, Florida State University, Tallahassee, Florida; Center for Translational Research in Aging and Longevity, Donald W. Reynolds Institute on Aging, University of Arkansas for Medical Sciences, Little Rock, Arkansas; and Human Biomechanics and Applied Physiology Lab, Department of Exercise Science, High Point University, One University Parkway, High Point, North Carolina
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10
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Marš T, Miš K, Meznarič M, Prpar Mihevc S, Jan V, Haugen F, Rogelj B, Rustan AC, Thoresen GH, Pirkmajer S, Nikolić N. Innervation and electrical pulse stimulation — in vitro effects on human skeletal muscle cells. Appl Physiol Nutr Metab 2021; 46:299-308. [DOI: 10.1139/apnm-2019-0575] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Contraction-induced adaptations in skeletal muscles are well characterized in vivo, but the underlying cellular mechanisms are still not completely understood. Cultured human myotubes represent an essential model system for human skeletal muscle that can be modulated ex vivo, but they are quiescent and do not contract unless being stimulated. Stimulation can be achieved by innervation of human myotubes in vitro by co-culturing with embryonic rat spinal cord, or by replacing motor neuron activation by electrical pulse stimulation (EPS). Effects of these two in vitro approaches, innervation and EPS, were characterized with respects to the expression of myosin heavy chains (MyHCs) and metabolism of glucose and oleic acid in cultured human myotubes. Adherent human myotubes were either innervated with rat spinal cord segments or exposed to EPS. The expression pattern of MyHCs was assessed by quantitative polymerase chain reaction, immunoblotting, and immunofluorescence, while the metabolism of glucose and oleic acid were studied using radiolabelled substrates. Innervation and EPS promoted differentiation towards different fiber types in human myotubes. Expression of the slow MyHC-1 isoform was reduced in innervated myotubes, whereas it remained unaltered in EPS-treated cells. Expression of both fast isoforms (MyHC-2A and MyHC-2X) tended to decrease in EPS-treated cells. Both approaches induced a more oxidative phenotype, reflected in increased CO2 production from both glucose and oleic acid. Novelty: Innervation and EPS favour differentiation into different fiber types in human myotubes. Both innervation and EPS promote a metabolically more oxidative phenotype in human myotubes.
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Affiliation(s)
- Tomaz Marš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Katarina Miš
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Marija Meznarič
- Institute of Anatomy, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Sonja Prpar Mihevc
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
| | - Vid Jan
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Fred Haugen
- Department of Work Psychology and Physiology, STAMI - The National Institute of Occupational Health, Oslo, Norway
| | - Boris Rogelj
- Department of Biotechnology, Jožef Stefan Institute, Ljubljana, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, Ljubljana, Slovenia
- Biomedical Research Institute (BRIS), Ljubljana, Slovenia
| | - Arild C. Rustan
- Department of Pharmacy, Section for Pharmacology and Pharmaceutical Biosciences, University of Oslo, Norway
| | - G. Hege Thoresen
- Department of Pharmacy, Section for Pharmacology and Pharmaceutical Biosciences, University of Oslo, Norway
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo, Norway
| | - Sergej Pirkmajer
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Nataša Nikolić
- Department of Pharmacy, Section for Pharmacology and Pharmaceutical Biosciences, University of Oslo, Norway
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11
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Gaffney K, Lucero A, Macartney-Coxson D, Clapham J, Whitfield P, Palmer BR, Wakefield S, Faulkner J, Stoner L, Rowlands DS. Effects of whey protein on skeletal muscle microvascular and mitochondrial plasticity following 10 weeks of exercise training in men with type 2 diabetes. Appl Physiol Nutr Metab 2021; 46:915-924. [PMID: 33591858 DOI: 10.1139/apnm-2020-0943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Skeletal muscle microvascular dysfunction and mitochondrial rarefaction feature in type 2 diabetes mellitus (T2DM) linked to low tissue glucose disposal rate (GDR). Exercise training and milk protein supplementation independently promote microvascular and metabolic plasticity in muscle associated with improved nutrient delivery, but combined effects are unknown. In a randomised-controlled trial, 24 men (55.6 y, SD 5.7) with T2DM ingested whey protein drinks (protein/carbohydrate/fat: 20/10/3 g; WHEY) or placebo (carbohydrate/fat: 30/3 g; CON) before/after 45 mixed-mode intense exercise sessions over 10 weeks, to study effects on insulin-stimulated (hyperinsulinemic clamp) skeletal-muscle microvascular blood flow (mBF) and perfusion (near-infrared spectroscopy), and histological, genetic, and biochemical markers (biopsy) of microvascular and mitochondrial plasticity. WHEY enhanced insulin-stimulated perfusion (WHEY-CON 5.6%; 90% CI -0.1, 11.3), while mBF was not altered (3.5%; -17.5, 24.5); perfusion, but not mBF, associated (regression) with increased GDR. Exercise training increased mitochondrial (range of means: 40%-90%) and lipid density (20%-30%), enzyme activity (20%-70%), capillary:fibre ratio (∼25%), and lowered systolic (∼4%) and diastolic (4%-5%) blood pressure, but without WHEY effects. WHEY dampened PGC1α -2.9% (90% compatibility interval: -5.7, -0.2) and NOS3 -6.4% (-1.4, -0.2) expression, but other messenger RNA (mRNA) were unclear. Skeletal muscle microvascular and mitochondrial exercise adaptations were not accentuated by whey protein ingestion in men with T2DM. ANZCTR Registration Number: ACTRN12614001197628. Novelty: Chronic whey ingestion in T2DM with exercise altered expression of several mitochondrial and angiogenic mRNA. Whey added no additional benefit to muscle microvascular or mitochondrial adaptations to exercise. Insulin-stimulated perfusion increased with whey but was without impact on glucose disposal.
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Affiliation(s)
- Kim Gaffney
- School of Sport, Exercise and Nutrition, Massey University, Wellington and Auckland, New Zealand
| | - Adam Lucero
- School of Sport, Exercise and Nutrition, Massey University, Wellington and Auckland, New Zealand
| | - Donia Macartney-Coxson
- Human Genomics, Institute of Environmental and Scientific Research Ltd (ESR). Porirua, Wellington, New Zealand
| | - Jane Clapham
- Human Genomics, Institute of Environmental and Scientific Research Ltd (ESR). Porirua, Wellington, New Zealand
| | | | - Barry R Palmer
- School of Health Sciences, Massey University, Wellington, New Zealand
| | - StJohn Wakefield
- Department of Medicine, University of Otago, Wellington, New Zealand
| | - James Faulkner
- School of Sport, Health and Community, University of Winchester, Winchester, England
| | - Lee Stoner
- Department of Exercise and Sport Science, University of North Carolina, Chapel Hill, NC, USA
| | - David S Rowlands
- School of Sport, Exercise and Nutrition, Massey University, Wellington and Auckland, New Zealand
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12
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Standley RA, Distefano G, Trevino MB, Chen E, Narain NR, Greenwood B, Kondakci G, Tolstikov VV, Kiebish MA, Yu G, Qi F, Kelly DP, Vega RB, Coen PM, Goodpaster BH. Skeletal Muscle Energetics and Mitochondrial Function Are Impaired Following 10 Days of Bed Rest in Older Adults. J Gerontol A Biol Sci Med Sci 2021; 75:1744-1753. [PMID: 31907525 PMCID: PMC7494044 DOI: 10.1093/gerona/glaa001] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Indexed: 12/02/2022] Open
Abstract
Background Older adults exposed to periods of inactivity during hospitalization, illness, or injury lose muscle mass and strength. This, in turn, predisposes poor recovery of physical function upon reambulation and represents a significant health risk for older adults. Bed rest (BR) results in altered skeletal muscle fuel metabolism and loss of oxidative capacity that have recently been linked to the muscle atrophy program. Our primary objective was to explore the effects of BR on mitochondrial energetics in muscle from older adults. A secondary objective was to examine the effect of β-hydroxy-β-methylbuturate (HMB) supplementation on mitochondrial energetics. Methods We studied 20 older adults before and after a 10-day BR intervention, who consumed a complete oral nutritional supplement (ONS) with HMB (3.0 g/d HMB, n = 11) or without HMB (CON, n = 9). Percutaneous biopsies of the vastus lateralis were obtained to determine mitochondrial respiration and H2O2 emission in permeabilized muscle fibers along with markers of content. RNA sequencing and lipidomics analyses were also conducted. Results We found a significant up-regulation of collagen synthesis and down-regulation of ribosome, oxidative metabolism and mitochondrial gene transcripts following BR in the CON group. Alterations to these gene transcripts were significantly blunted in the HMB group. Mitochondrial respiration and markers of content were both reduced and H2O2 emission was elevated in both groups following BR. Conclusions In summary, 10 days of BR in older adults causes a significant deterioration in mitochondrial energetics, while transcriptomic profiling revealed that some of these negative effects may be attenuated by an ONS containing HMB.
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Affiliation(s)
| | | | - Michelle B Trevino
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida
| | | | | | | | | | | | | | - Gongxin Yu
- AdventHealth Translational Research Institute, Orlando, Florida
| | - Feng Qi
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida
| | - Daniel P Kelly
- Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida.,Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania, Philadelphia
| | - Rick B Vega
- AdventHealth Translational Research Institute, Orlando, Florida.,Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida
| | - Paul M Coen
- AdventHealth Translational Research Institute, Orlando, Florida
| | - Bret H Goodpaster
- AdventHealth Translational Research Institute, Orlando, Florida.,Center for Metabolic Origins of Disease, Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida
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13
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Chee C, Shannon CE, Burns A, Selby AL, Wilkinson D, Smith K, Greenhaff PL, Stephens FB. Increasing skeletal muscle carnitine content in older individuals increases whole-body fat oxidation during moderate-intensity exercise. Aging Cell 2021; 20:e13303. [PMID: 33464721 PMCID: PMC7884033 DOI: 10.1111/acel.13303] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 11/20/2020] [Accepted: 12/21/2020] [Indexed: 12/13/2022] Open
Abstract
Intramyocellular lipid (IMCL) utilization is impaired in older individuals, and IMCL accumulation is associated with insulin resistance. We hypothesized that increasing muscle total carnitine content in older men would increase fat oxidation and IMCL utilization during exercise, and improve insulin sensitivity. Fourteen healthy older men (69 ± 1 year, BMI 26.5 ± 0.8 kg/m2 ) performed 1 h of cycling at 50% VO2 max and, on a separate occasion, underwent a 60 mU/m2 /min euglycaemic hyperinsulinaemic clamp before and after 25 weeks of daily ingestion of a 220 ml insulinogenic beverage (44.4 g carbohydrate, 13.8 g protein) containing 4.5 g placebo (n = 7) or L-carnitine L-tartrate (n = 7). During supplementation, participants performed twice-weekly cycling for 1 h at 50% VO2 max. Placebo ingestion had no effect on muscle carnitine content or total fat oxidation during exercise at 50% VO2 max. L-carnitine supplementation resulted in a 20% increase in muscle total carnitine content (20.1 ± 1.2 to 23.9 ± 1.7 mmol/kg/dm; p < 0.01) and a 20% increase in total fat oxidation (181.1 ± 15.0 to 220.4 ± 19.6 J/kg lbm/min; p < 0.01), predominantly due to increased IMCL utilization. These changes were associated with increased expression of genes involved in fat metabolism (ACAT1, DGKD & PLIN2; p < 0.05). There was no change in resting insulin-stimulated whole-body or skeletal muscle glucose disposal after supplementation. This is the first study to demonstrate that a carnitine-mediated increase in fat oxidation is achievable in older individuals. This warrants further investigation given reduced lipid turnover is associated with poor metabolic health in older adults.
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Affiliation(s)
- Carolyn Chee
- MRC/Versus Arthritis Centre for Musculoskeletal Ageing ResearchSchool of Life SciencesUniversity of NottinghamNottinghamUK
| | - Chris E. Shannon
- Diabetes DivisionUniversity of Texas Health Science CentreSan AntonioTXUSA
| | - Aisling Burns
- Sam and Ann Barshop Institute for Longevity and Aging StudiesUniversity of Texas Health Science CentreSan AntonioTXUSA
| | - Anna L. Selby
- MRC/Versus Arthritis Centre for Musculoskeletal Ageing ResearchSchool of MedicineUniversity of NottinghamNottinghamUK
| | - Daniel Wilkinson
- MRC/Versus Arthritis Centre for Musculoskeletal Ageing ResearchSchool of MedicineUniversity of NottinghamNottinghamUK
| | - Kenneth Smith
- MRC/Versus Arthritis Centre for Musculoskeletal Ageing ResearchSchool of MedicineUniversity of NottinghamNottinghamUK
| | - Paul L. Greenhaff
- MRC/Versus Arthritis Centre for Musculoskeletal Ageing ResearchSchool of Life SciencesUniversity of NottinghamNottinghamUK
| | - Francis B. Stephens
- Department of Sport and Health SciencesSt Luke's CampusUniversity of ExeterExeterUK
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14
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A 12-week aerobic exercise intervention results in improved metabolic function and lower adipose tissue and ectopic fat in high-fat diet fed rats. Biosci Rep 2021; 41:227560. [PMID: 33432988 PMCID: PMC7846962 DOI: 10.1042/bsr20201707] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Revised: 12/25/2020] [Accepted: 01/07/2021] [Indexed: 02/06/2023] Open
Abstract
Investigations of long-term exercise interventions in humans to reverse obesity is expensive and is hampered by poor compliance and confounders. In the present study, we investigated intrahepatic and muscle fat, visceral and subcutaneous fat pads, plasma metabolic profile and skeletal muscle inflammatory markers in response to 12-week aerobic exercise in an obese rodent model. Six-week-old male Wistar rats (n=20) were randomized to chow-fed control (Control, n=5), sedentary high-fat diet (HFD, n=5), chow-fed exercise (Exercise, n=5) and HFD-fed exercise (HFD+Exercise, n=5) groups. The exercise groups were subjected to 12 weeks of motorized treadmill running at a speed of 18 m/min for 30 min/day. Differences in post-intervention measures were assessed by analysis of covariance (ANCOVA), adjusted for baseline bodyweight and pre-intervention measures, where available. Post-hoc analyses were performed with Bonferroni correction. Plasma metabolic profile was worsened and fat pads, ectopic fat in muscle and liver and inflammatory markers in skeletal muscle were elevated in sedentary HFD-fed animals relative to chow-fed controls. HFD+Exercise animals had significantly lower leptin (P=0.0004), triglycerides (P=0.007), homeostatic model assessment of insulin resistance (HOMA-IR; P=0.065), intramyocellular lipids (IMCLs; P=0.003), intrahepatic lipids (IHLs; P<0.0001), body fat% (P=0.001), subcutaneous adipose tissue (SAT; P<0.0001), visceral adipose (P<0.0001) and total fat mass (P<0.0001), relative to sedentary HFD-fed animals, despite only modestly lower bodyweight. Messenger RNA (mRNA) expression of inflammatory markers Interleukin 6 (IL6) and Tumor necrosis factor α (TNFα) were also reduced with aerobic exercise in skeletal muscle. Our results suggest that 12 weeks of aerobic exercise training is effective in improving metabolic health, fat depots, ectopic fat and inflammation even against a high-fat dietary background.
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15
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Maltais A, Lemieux I, Alméras N, Tremblay A, Bergeron J, Poirier P, Després JP. One-Year Lifestyle Intervention, Muscle Lipids, and Cardiometabolic Risk. Med Sci Sports Exerc 2020; 51:2156-2165. [PMID: 31525173 DOI: 10.1249/mss.0000000000002030] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
PURPOSE Low-attenuation muscle (LAM) area at mid-thigh, a computed tomography (CT)-derived index of intramuscular lipids, is associated with insulin resistance, obesity, and type 2 diabetes. The present study aimed at testing the hypothesis that changes in LAM area in trunk muscles from a single abdominal scan could provide relevant information to evaluate the effects of a lifestyle intervention without the use of a mid-thigh CT scan. METHODS Cardiometabolic risk variables, including waist circumference, lipoprotein-lipid profile, glucose tolerance, and cardiorespiratory fitness, were assessed in a sample of 102 dyslipidemic viscerally obese men at baseline and after a 1-yr lifestyle intervention. Abdominal (L4-L5) and mid-thigh CT scans were performed and abdominal muscles classified as psoas and core muscles. Scans were segmented to calculate muscle areas, LAM areas, and mean attenuation values. RESULTS All muscle groups showed a decrease in LAM areas (P < 0.0001) in response to the lifestyle intervention. Changes in LAM areas were significantly associated with changes in triglycerides, high-density lipoprotein (HDL) cholesterol, cholesterol/HDL cholesterol ratio and log triglycerides/HDL cholesterol ratio (mid-thigh, 0.20 ≤ |r| ≤ 0.29; psoas, 0.28 ≤ |r| ≤ 0.38; core, 0.29 ≤ |r| ≤ 0.34, P < 0.05). Changes in core LAM area were significantly associated with changes in 2-h glucose levels, glucose area measured during the oral glucose tolerance test and homeostasis model assessment of insulin resistance (0.21 ≤ r ≤ 0.34, P < 0.05). Stepwise regression analyses showed that changes in LAM psoas area were associated with changes in HDL cholesterol and the cholesterol/HDL cholesterol ratio independently from changes in visceral adiposity. CONCLUSIONS Changes in trunk LAM areas are useful indices of changes in mid-thigh LAM area observed with a 1-yr lifestyle intervention. Thus, an additional mid-thigh scan is not necessary to evaluate muscle lipid content by CT when an abdominal CT scan is available.
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Affiliation(s)
- Alexandre Maltais
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, QC, CANADA.,Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, QC, CANADA
| | - Isabelle Lemieux
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, QC, CANADA
| | - Natalie Alméras
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, QC, CANADA.,Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, QC, CANADA
| | - Angelo Tremblay
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, QC, CANADA.,Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, QC, CANADA
| | - Jean Bergeron
- Endocrinology and Nephrology Unit, CHU de Québec, Université Laval Research Center, Québec, QC, CANADA
| | - Paul Poirier
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, QC, CANADA.,Faculty of Pharmacy, Université Laval, Québec, QC, CANADA
| | - Jean-Pierre Després
- Centre de recherche de l'Institut universitaire de cardiologie et de pneumologie de Québec-Université Laval, Québec, QC, CANADA.,Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, QC, CANADA
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16
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Both higher fitness level and higher current physical activity level may be required for intramyocellular lipid accumulation in non-athlete men. Sci Rep 2020; 10:4102. [PMID: 32139784 PMCID: PMC7057967 DOI: 10.1038/s41598-020-61080-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 02/20/2020] [Indexed: 11/25/2022] Open
Abstract
Accumulation of intramyocellular lipid (IMCL) is observed in individuals with insulin resistance as well as insulin-sensitive endurance athletes with high peak oxygen consumption (VO2peak), which is called the athlete’s paradox. It remains unclear whether non-athletes with higher fitness levels have IMCL accumulation and higher insulin sensitivity in general. In this study, we investigated the association between IMCL accumulation and muscle insulin sensitivity (M-IS) in subjects with high or low VO2peak. We studied 61 nonobese (BMI, 23 to 25 kg/m2), non-athlete Japanese men. We divided the subjects into four groups based on the median value of VO2peak and IMCL in the soleus muscle. We evaluated M-IS using a two-step hyperinsulinemic-euglycemic clamp. Among subjects with higher VO2peak (n = 32), half of those (n = 16) had lower IMCL levels. Both High-VO2peak groups had higher M-IS than the Low-VO2peak groups. On the other hand, M-IS was comparable between the High-VO2peak/High-IMCL and High-VO2peak/Low-IMCL groups, whereas the High-VO2peak/High-IMCL group had IMCL levels that were twice as high as those in the High-VO2peak/Low-IMCL group. On the other hand, the High-VO2peak/High-IMCL group had significantly higher physical activity levels (approximately 1.8-fold) than the other three groups. In conclusion, in nonobese, non-athlete Japanese men, subjects with higher VO2peak and higher IMCL had higher physical activity levels. IMCL accumulation is not associated with insulin resistance in individuals with higher or lower fitness levels.
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17
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Brennan AM, Standley RA, Yi F, Carnero EA, Sparks LM, Goodpaster BH. Individual Response Variation in the Effects of Weight Loss and Exercise on Insulin Sensitivity and Cardiometabolic Risk in Older Adults. Front Endocrinol (Lausanne) 2020; 11:632. [PMID: 33013705 PMCID: PMC7511700 DOI: 10.3389/fendo.2020.00632] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 08/04/2020] [Indexed: 12/29/2022] Open
Abstract
Weight loss induced by decreased energy intake (diet) or exercise generally has favorable effects on insulin sensitivity and cardiometabolic risk. The variation in these responses to diet-induced weight loss with or without exercise, particularly in older obese adults, is less clear. The objectives of our study were to (1) examine the effect of weight loss with or without exercise on the variability of responses in insulin sensitivity and cardiometabolic risk factors and (2) to explore whether baseline phenotypic characteristics are associated with response. Sedentary older obese (BMI 36.3 ± 5.0 kg/m2) adults (68.6 ± 4.7 years) were randomized to one of 3 groups: health education control (HED); diet-induced weight loss (WL); or weight loss and exercise (WL + EX) for 6 months. Composite Z-scores were calculated for changes in insulin sensitivity (C_IS: rate of glucose disposal/insulin at steady state during hyperinsulinemic euglycemic clamp, HOMA-IR, and HbA1C) and cardiometabolic risk (C_CMR: waist circumference, triglycerides, and fasting glucose). Baseline measures included body composition (MRI), cardiorespiratory fitness, in vivo mitochondrial function (ATPmax; P-MRS), and muscle fiber type. WL + EX groups had a greater proportion of High Responders in both C_IS and C_CMR compared to HED and WL only (all p < 0.05). Pre-intervention measures of insulin (r = 0.60) and HOMA-IR (r = 0.56) were associated with change in insulin sensitivity (C_IS) in the WL group (p < 0.05). Pre-intervention measures of glucose (r = 0.55), triglycerides (r = 0.53), and VLDL (r = 0.53) were associated with change in cardiometabolic risk (C_CMR) in the WL group (p < 0.05), whereas triglycerides (r = 0.59) and VLDL (r = 0.59) were associated with C_CMR (all p < 0.05) in WL + EX. Thus, the addition of exercise to diet-induced weight loss increases the proportion of older obese adults who improve insulin sensitivity and cardiometabolic risk. Additionally, individuals with poorer metabolic status are more likely to experience greater improvements in cardiometabolic risk during weight loss with or without exercise.
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18
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Consitt LA, Dudley C, Saxena G. Impact of Endurance and Resistance Training on Skeletal Muscle Glucose Metabolism in Older Adults. Nutrients 2019; 11:nu11112636. [PMID: 31684154 PMCID: PMC6893763 DOI: 10.3390/nu11112636] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 10/14/2019] [Accepted: 10/18/2019] [Indexed: 12/20/2022] Open
Abstract
Aging is associated with insulin resistance and the development of type 2 diabetes. While this process is multifaceted, age-related changes to skeletal muscle are expected to contribute to impaired glucose metabolism. Some of these changes include sarcopenia, impaired insulin signaling, and imbalances in glucose utilization. Endurance and resistance exercise training have been endorsed as interventions to improve glucose tolerance and whole-body insulin sensitivity in the elderly. While both types of exercise generally increase insulin sensitivity in older adults, the metabolic pathways through which this occurs can differ and can be dependent on preexisting conditions including obesity and type 2 diabetes. In this review, we will first highlight age-related changes to skeletal muscle which can contribute to insulin resistance, followed by a comparison of endurance and resistance training adaptations to insulin-stimulated glucose metabolism in older adults.
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Affiliation(s)
- Leslie A Consitt
- Department of Biomedical Sciences, Ohio University, Athens, OH 45701, USA.
- Ohio Musculoskeletal and Neurological Institute, Ohio University, Athens, OH 45701, USA.
- Diabetes Institute, Ohio University, Athens, OH 45701, USA.
| | - Courtney Dudley
- Department of Biological Sciences, Ohio University, Athens, OH 45701, USA.
| | - Gunjan Saxena
- Department of Biomedical Sciences, Ohio University, Athens, OH 45701, USA.
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19
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Trevino MB, Zhang X, Standley RA, Wang M, Han X, Reis FCG, Periasamy M, Yu G, Kelly DP, Goodpaster BH, Vega RB, Coen PM. Loss of mitochondrial energetics is associated with poor recovery of muscle function but not mass following disuse atrophy. Am J Physiol Endocrinol Metab 2019; 317:E899-E910. [PMID: 31479303 PMCID: PMC6879870 DOI: 10.1152/ajpendo.00161.2019] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 08/27/2019] [Accepted: 08/27/2019] [Indexed: 12/20/2022]
Abstract
Skeletal muscle atrophy is a clinically important outcome of disuse because of injury, immobilization, or bed rest. Disuse atrophy is accompanied by mitochondrial dysfunction, which likely contributes to activation of the muscle atrophy program. However, the linkage of muscle mass and mitochondrial energetics during disuse atrophy and its recovery is incompletely understood. Transcriptomic analysis of muscle biopsies from healthy older adults subject to complete bed rest revealed marked inhibition of mitochondrial energy metabolic pathways. To determine the temporal sequence of muscle atrophy and changes in intramyocellular lipid and mitochondrial energetics, we conducted a time course of hind limb unloading-induced atrophy in adult mice. Mitochondrial respiration and calcium retention capacity were diminished, whereas H2O2 emission was increased within 3 days of unloading before significant muscle atrophy. These changes were associated with a decrease in total cardiolipin and profound changes in remodeled cardiolipin species. Hind limb unloading performed in muscle-specific peroxisome proliferator-activated receptor-γ coactivator-1α/β knockout mice, a model of mitochondrial dysfunction, did not affect muscle atrophy but impacted muscle function. These data suggest early mitochondrial remodeling affects muscle function but not mass during disuse atrophy. Early alterations in mitochondrial energetics and lipid remodeling may represent novel targets to prevent muscle functional impairment caused by disuse and to enhance recovery from periods of muscle atrophy.
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Affiliation(s)
- Michelle B Trevino
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida
| | - Xiaolei Zhang
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida
- Translational Research Institute for Metabolism and Diabetes, AdventHealth, Orlando, Florida
| | - Robert A Standley
- Translational Research Institute for Metabolism and Diabetes, AdventHealth, Orlando, Florida
| | - Miao Wang
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida
| | - Xianlin Han
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida
| | - Felipe C G Reis
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida
| | - Muthu Periasamy
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida
| | - Gongxin Yu
- Translational Research Institute for Metabolism and Diabetes, AdventHealth, Orlando, Florida
| | - Daniel P Kelly
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida
- Cardiovascular Research Institute and Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Bret H Goodpaster
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida
- Translational Research Institute for Metabolism and Diabetes, AdventHealth, Orlando, Florida
| | - Rick B Vega
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida
- Translational Research Institute for Metabolism and Diabetes, AdventHealth, Orlando, Florida
| | - Paul M Coen
- Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, Florida
- Translational Research Institute for Metabolism and Diabetes, AdventHealth, Orlando, Florida
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20
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Wilhelmsen A, Mallinson J, Jones R, Cooper S, Taylor T, Tsintzas K. Chronic effects of high-intensity interval training on postprandial lipemia in healthy men. J Appl Physiol (1985) 2019; 127:1763-1771. [PMID: 31622161 DOI: 10.1152/japplphysiol.00131.2019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The aim of this study was to determine the chronic (≥72 h postexercise) effects of high-intensity interval training (HIIT) on postprandial lipemia and metabolic markers in healthy volunteers. Eight physically active young men (mean ± SD: age 22 ± 3 yr, height 1.77 ± 0.07 m, body mass 67.7 ± 6.2 kg) underwent two 6-h mixed-meal tolerance tests and resting vastus lateralis muscle biopsies before the first session and ≥72 h after the final session of 4 wk of HIIT [16 sessions in total; 10 × 60-s bouts of cycling at 90% maximal oxygen uptake (V̇o2max), interspersed with 60-s intervals at 45% V̇o2max]. Arterialized and deep venous blood samples from across the forearm, brachial artery blood flow measurements, and whole-body indirect calorimetry data were obtained before, and at regular intervals for 6 h after, consumption of a standardized mixed meal. The main findings revealed that, when assessed ≥72 h postexercise, postprandial free fatty acid (FFA) uptake across the forearm was increased in response to exercise training (P = 0.025). However, 4 wk of HIIT did not alter fasting or postprandial circulating triglyceride concentrations or their tissue uptake, despite a 10.2% ± 7.7% improvement in V̇o2max (P = 0.004). Protein content of adipose triglyceride lipase in the vastus lateralis at rest was reduced by 25% ± 21% (P = 0.01). Collectively, these findings suggest that 4 wk of HIIT enhances postprandial clearance of FFA when assessed ≥72 h postexercise but does not confer persisting (training) adaptations in postprandial triglyceridemia.NEW & NOTEWORTHY When assessed ≥72 h after the last exercise session, 4 wk of high-intensity interval training (HIIT) did not improve triglyceridemia but enhanced free fatty acid uptake into muscle with a concurrent reduction in skeletal muscle adipose triglyceride lipase protein content. This suggests that previously reported acute reductions in postprandial triglyceridemia following a single bout of HIIT do not translate to sustained improvements after 4 wk of HIIT, supporting the concept of frequent exercise for the maintenance of lipemic control.
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Affiliation(s)
- Andrew Wilhelmsen
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Joanne Mallinson
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Robert Jones
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Scott Cooper
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Tariq Taylor
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
| | - Kostas Tsintzas
- MRC Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Queen's Medical Centre, Nottingham, United Kingdom
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21
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Pino MF, Stephens NA, Eroshkin AM, Yi F, Hodges A, Cornnell HH, Pratley RE, Smith SR, Wang M, Han X, Coen PM, Goodpaster BH, Sparks LM. Endurance training remodels skeletal muscle phospholipid composition and increases intrinsic mitochondrial respiration in men with Type 2 diabetes. Physiol Genomics 2019; 51:586-595. [PMID: 31588872 DOI: 10.1152/physiolgenomics.00014.2019] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The effects of exercise training on the skeletal muscle (SKM) lipidome and mitochondrial function have not been thoroughly explored in individuals with Type 2 diabetes (T2D). We hypothesize that 10 wk of supervised endurance training improves SKM mitochondrial function and insulin sensitivity that are related to alterations in lipid signatures within SKM of T2D (males n = 8). We employed integrated multi-omics data analyses including ex vivo lipidomics (MS/MS-shotgun) and transcriptomics (RNA-Seq). From biopsies of SKM, tissue and primary myotubes mitochondrial respiration were quantified by high-resolution respirometry. We also performed hyperinsulinemic-euglycemic clamps and blood draws before and after the training. The lipidomics analysis revealed that endurance training (>95% compliance) increased monolysocardiolipin by 68.2% (P ≤ 0.03), a putative marker of mitochondrial remodeling, and reduced total sphingomyelin by 44.8% (P ≤ 0.05) and phosphatidylserine by 39.7% (P ≤ 0.04) and tended to reduce ceramide lipid content by 19.8%. Endurance training also improved intrinsic mitochondrial respiration in SKM of T2D without alterations in mitochondrial DNA copy number or cardiolipin content. RNA-Seq revealed 71 transcripts in SKM of T2D that were differentially regulated. Insulin sensitivity was unaffected, and HbA1c levels moderately increased by 7.3% despite an improvement in cardiorespiratory fitness (V̇o2peak) following the training intervention. In summary, endurance training improves intrinsic and cell-autonomous SKM mitochondrial function and modifies lipid composition in men with T2D independently of alterations in insulin sensitivity and glycemic control.
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Affiliation(s)
- Maria F Pino
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Natalie A Stephens
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Alexey M Eroshkin
- Sanford Burnham Prebys Medical Discovery Institute, Torrey Pines, California
| | - Fanchao Yi
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Andrew Hodges
- Sanford Burnham Prebys Medical Discovery Institute, Torrey Pines, California
| | - Heather H Cornnell
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Richard E Pratley
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Steven R Smith
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Miao Wang
- University of Texas Health Sciences Center San Antonio, San Antonio, Texas
| | - Xianlin Han
- University of Texas Health Sciences Center San Antonio, San Antonio, Texas
| | - Paul M Coen
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Bret H Goodpaster
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
| | - Lauren M Sparks
- Translational Research Institute for Metabolism and Diabetes, Adventhealth, Orlando, Florida
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22
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Marquezi ML, Agostinho CFM, Lima FRD, Aparecido JML, Cascapera MS. SIX HIT TREADMILL SESSIONS IMPROVE LIPID OXIDATION AND VENTILATORY THRESHOLD INTENSITIES. REV BRAS MED ESPORTE 2019. [DOI: 10.1590/1517-869220192504169653] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
ABSTRACT Introduction: High-intensity interval training (HIT) has been used as an alternative to cardiorespiratory training performed continuously at submaximal intensity and over long periods. Objectives: Propose a treadmill HIT protocol and verify the influence of six HIT sessions with this protocol on ventilatory anaerobic thresholds (VATs) and substrate oxidation pattern during submaximal continuous exercise (SCE). Methods: Fifteen sporadically active subjects underwent maximal progressive testing before and after six HIT treadmill running sessions to determine peak oxygen uptake (VO2peak), peak velocity (Vpeak), and VATs followed by SCE to determine lipid (LIPox) and carbohydrate (CHOox) oxidation rates. The HIT sessions consisted of eight sets of 60s at 100%Vpeak, interspersed with 75s of passive recovery between sets and a 48h interval between sessions. Results: Our results showed increases in VAT intensities of 4.4% for VAT1 and 8.8% for VAT2, a decrease of 12.8% in CHOox and an increase of 23.7% for LIPox; accordingly, the relative energy derived from LIPox was 20.3% higher after the training period. Vpeak was ~15 km/h, producing intensities corresponding to ~84%VO2peak and ~91%FCpeak over the training period. Conclusion: The proposed protocol produced adaptations and intensities which are similar to those described in the literature, but unlike others, it can be applied in sporadically active individuals. Level of Evidence II; Comparative prospective study.
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23
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Moreillon M, Conde Alonso S, Broskey NT, Greggio C, Besson C, Rousson V, Amati F. Hybrid fiber alterations in exercising seniors suggest contribution to fast-to-slow muscle fiber shift. J Cachexia Sarcopenia Muscle 2019; 10:687-695. [PMID: 30907516 PMCID: PMC6596392 DOI: 10.1002/jcsm.12410] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 01/27/2019] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Human skeletal muscle is composed of a functional and metabolic continuum of slow (Type I) and fast fibers (IIa and IIx). Hybrid fibers co-expressing different myosin heavy chains are also present and seem to be more prominent in aging muscle. Their role is debated; hybrid fibers were reported either in a transitional state, between slow and fast fibers, or as fixed individual entities. This study examined the fate of hybrid fibers with an endurance exercise intervention in an elderly sedentary population. METHODS Twenty-two sedentary healthy elderly men and women underwent a 16-week supervised endurance exercise intervention. Eighteen endurance-trained age- and gender-matched volunteers served as controls. Fiber type distribution was determined by immunohistochemistry on vastus lateralis muscle biopsies pre-intervention and post-intervention. RESULTS A total of 13840 fibers were analyzed. At baseline, a Type II dominant fiber profile was observed compared with the control group, with more Type IIa (P = 0.0301) and Type IIx fibers (P = 0.0328). Hybrid fibers represented almost 5% of total muscle fibers in both groups. There was no significant difference between groups (I-IIa, P = 0.6719 and IIa-IIx, P = 0.0998). Intervention triggered qualitative dynamics towards an increase in Type I, and decrease in Type II fibers, paralleled by an increase in I-IIa hybrids (P = 0.0301). CONCLUSIONS The present study is, to our knowledge, the first to examine hybrid muscle fiber type adaptations to an endurance exercise intervention in the elderly. Hybrid fiber proportions did not differ between chronic sedentary state and chronic endurance-trained state. Exercise intervention increased Type I-IIa hybrid fibers along with shift dynamics in other fiber types suggesting the contribution of hybrid fiber to a fast-to-slow fiber type transition, eventually serving as intermediate reservoir from one monomorphic myosin heavy chain expressing fiber type to another. This finding favours the transitional theory regarding hybrid muscle fibers and exercise, crucial to understanding reversible mechanisms of sarcopenia and development of prevention measures.
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Affiliation(s)
- Maxime Moreillon
- Aging and Muscle Metabolism Lab, Department of Physiology & Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Sonia Conde Alonso
- Aging and Muscle Metabolism Lab, Department of Physiology & Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Nicholas T Broskey
- Aging and Muscle Metabolism Lab, Department of Physiology & Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Chiara Greggio
- Aging and Muscle Metabolism Lab, Department of Physiology & Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Cyril Besson
- Sports Medicine Unit, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Valentin Rousson
- Division of Biostatistics and Quantitative Methods, Institute of Social and Preventive Medicine, University of Lausanne, Lausanne, Switzerland
| | - Francesca Amati
- Aging and Muscle Metabolism Lab, Department of Physiology & Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland.,Sports Medicine Unit, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland.,Service of Endocrinology, Diabetology and Metabolism, Department of Medicine, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
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24
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Local In Vivo Measures of Muscle Lipid and Oxygen Consumption Change in Response to Combined Vitamin D Repletion and Aerobic Training in Older Adults. Nutrients 2019; 11:nu11040930. [PMID: 31027191 PMCID: PMC6521174 DOI: 10.3390/nu11040930] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 04/18/2019] [Accepted: 04/22/2019] [Indexed: 12/31/2022] Open
Abstract
Intramyocellular (IMCL), extramyocellular lipid (EMCL), and vitamin D deficiency are associated with muscle metabolic dysfunction. This study compared the change in [IMCL]:[EMCL] following the combined treatment of vitamin D and aerobic training (DAT) compared with vitamin D (D), aerobic training (AT), and control (CTL). Male and female subjects aged 60–80 years with a BMI ranging from 18.5–34.9 and vitamin D status of ≤32 ng/mL (25(OH)D) were recruited to randomized, prospective clinical trial double-blinded for supplement with a 2 × 2 factorial design. Cholecalciferol (Vitamin D3) (10,000 IU × 5 days/week) or placebo was provided for 13 weeks and treadmill aerobic training during week 13. Gastrocnemius IMCL and EMCL were measured with magnetic resonance spectroscopy (MRS) and MRI. Hybrid near-infrared diffuse correlation spectroscopy measured hemodynamics. Group differences in IMCL were observed when controlling for baseline IMCL (p = 0.049). DAT was the only group to reduce IMCL from baseline, while a mean increase was observed in all other groups combined (p = 0.008). IMCL reduction and the corresponding increase in rVO2 at study end (p = 0.011) were unique to DAT. Vitamin D, when combined with exercise, may potentiate the metabolic benefits of exercise by reducing IMCL and increasing tissue-level VO2 in healthy, older adults.
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Yoshiko A, Kaji T, Sugiyama H, Koike T, Oshida Y, Akima H. Twenty-Four Months' Resistance and Endurance Training Improves Muscle Size and Physical Functions but Not Muscle Quality in Older Adults Requiring Long-Term Care. J Nutr Health Aging 2019; 23:564-570. [PMID: 31233079 DOI: 10.1007/s12603-019-1208-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVES To assess the effects of 24 months training on muscle quality, size, strength, and gait abilities in older adults who need long-term care. DESIGN Non-randomized controlled trial Setting: Kawai Rehabilitation Center and Kajinoki Medical Clinic. PARTICIPANTS Ten older participants who needed long-term care (age, 76.7 ± 5.6 years) were participated as training group (Tr-group) and 10 older men and women who did not require long-term care (age, 72.9 ± 6.6 years) comprised the control group (Cont-group). INTERVENTION Tr-group performed resistive and endurance exercises once or twice a week for 24 months. MEASUREMENTS Using ultrasound images, echo intensity (EI) and muscle thickness were measured in the rectus femoris and biceps femoris as an index of muscle quality and size. Physical performance was measured before and after the training; performance parameters included knee extension peak torque, 5-m normal and maximal walk test, sit-to-stand and timed up and go test. RESULTS After the training, there was no change in EI, while BF thickness was increased (pre; 1.82 ± 0.29 cm, 24 months; 2.14 ± 0.23 cm, p < 0.05) in Tr-group. Walk-related performances were improved after the training in Tr-group (i.e. 5-m walk test and timed up and go test). The percent change of knee extension peak torque explained the percent change of EI in the rectus femoris (regression coefficient = 1.24, R = 0.91, adjusted R2 = 0.82, p < 0.001). CONCLUSIONS Twenty-four months' training induced muscle hypertrophy and improved physical functions. Increased muscle quality in the rectus femoris could be a key to improved knee extension peak torque, with the potential to eventually reduce the need for long-term care in older individuals.
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Affiliation(s)
- A Yoshiko
- Akito Yoshiko, Ph.D. School of International Liberal Studies, Chukyo University, 101 Tokodachi, Kaizu, Toyota, Aichi 470-0393, Japan, Tel: +81 (565) 46-6952, E-mail:
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26
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Schnell DM, Walton RG, Vekaria HJ, Sullivan PG, Bollinger LM, Peterson CA, Thomas DT. Vitamin D produces a perilipin 2-dependent increase in mitochondrial function in C2C12 myotubes. J Nutr Biochem 2018; 65:83-92. [PMID: 30658160 DOI: 10.1016/j.jnutbio.2018.11.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 10/11/2018] [Accepted: 11/10/2018] [Indexed: 02/08/2023]
Abstract
Vitamin D has been connected with increased intramyocellular lipid (IMCL) and has also been shown to increase mitochondrial function and insulin sensitivity. Evidence suggests that perilipin 2 (PLIN2), a perilipin protein upregulated with calcitriol treatment, may be integral to managing increased IMCL capacity and lipid oxidation in skeletal muscle. Therefore, we hypothesized that PLIN2 is required for vitamin D induced IMCL accumulation and increased mitochondrial oxidative function. To address this hypothesis, we treated C2C12 myotubes with 100 nM calcitriol (the active form of vitamin D) and/or PLIN2 siRNA in a four group design and analyzed markers of IMCL accumulation and metabolism using qRT-PCR, cytochemistry, and oxygen consumption assay. Expression of PLIN2, but not PLIN3 or PLIN5 mRNA was increased with calcitriol, and PLIN2 induction was prevented with siRNA knockdown without compensation by other perilipins. PLIN2 knockdown did not appear to prevent lipid accumulation. Calcitriol treatment increased mRNA expression of triglyceride synthesizing genes DGAT1 and DGAT2 and also lipolytic genes ATGL and CGI-58. PLIN2 knockdown decreased the expression of CGI-58 and CPT1, and was required for calcitriol-induced upregulation of DGAT2. Calcitriol increased oxygen consumption rate while PLIN2 knockdown decreased oxygen consumption rate. PLIN2 was required for a calcitriol-induced increase in oxygen consumption driven by mitochondrial complex II. We conclude that calcitriol increases mitochondrial function in myotubes and that this increase is at least in part mediated by PLIN2.
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Affiliation(s)
| | - R Grace Walton
- Department of Rehabilitation Sciences; Center for Muscle Biology.
| | | | | | | | | | - D Travis Thomas
- Department of Clinical Sciences, University of Kentucky, Lexington, KY 40536.
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27
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Fischer M, Oberänder N, Kaufmann J, Kirsche V, Prodehl G, Schäfer AO, Weimann A. Changes in intra- and extramyocellular lipids in morbidly obese patients after non-surgical weight loss-a pilot study using magnetic resonance spectroscopy. Clin Nutr ESPEN 2018; 28:121-126. [PMID: 30390868 DOI: 10.1016/j.clnesp.2018.08.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 08/25/2018] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS Lipid accumulation in muscles is common in obesity and associated with increased risks for insulin resistance. However, the impact of weight loss and exercise on muscle fat content is not clear due to inconsistent data. We used magnetic resonance spectroscopy (MRS) to compare the intra- (IMCL) and extramyocellular lipid (EMCL) proportions in the musculus tibialis anterior of extremely obese patients before and after weight loss. METHODS Nineteen non-diabetic patients with a Body Mass Index (BMI) ≥ 40 kg/m2 who participated in a non-surgical multimodal weight loss program were recruited. Metabolite ratios of IMCL and EMCL (metabolite/creatine) were assessed using 3 T 1H-MRS before therapy and after 6 months. The primary outcome comprised changes in IMCL and body cell mass. Additionally, changes of IMCL and EMCL were compared with changes in standard clinical measures, i.e., BMI, body composition, blood pressure and functional exercise capacity. RESULTS After 6 months the relative weight loss was 24.8% (127.6 kg, 48.5 kg/m2 vs. 96 kg, 36.5 kg/m2). All standard clinical measures were significantly improved. MRS data from 10 patients provided complete and evaluable data sets. IMCL was reduced by nearly 50% (p < .05). The reduction of EMCL was not significant (p = .106). An explorative correlation analysis between changes of IMCL and changes of the standard measures did not reveal any significance. CONCLUSIONS Significant reductions of IMCL following a successful conservative weight loss intervention are detectable by using MRS. These changes may have the potential to serve as an additional marker of clinically meaningful obesity treatment.
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Affiliation(s)
- Martin Fischer
- St. George Obesity Treatment Study Group, Klinikum St. Georg, 04129 Leipzig, Germany
| | - Nadine Oberänder
- St. George Obesity Treatment Study Group, Klinikum St. Georg, 04129 Leipzig, Germany
| | - Jörn Kaufmann
- Neurologische Universitätsklinik, Otto-von-Guericke Universität Magdeburg, Germany
| | - Viktor Kirsche
- St. George Obesity Treatment Study Group, Klinikum St. Georg, 04129 Leipzig, Germany
| | - Guido Prodehl
- St. George Obesity Treatment Study Group, Klinikum St. Georg, 04129 Leipzig, Germany
| | | | - Arved Weimann
- St. George Obesity Treatment Study Group, Klinikum St. Georg, 04129 Leipzig, Germany.
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28
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Stanford KI, Lynes MD, Takahashi H, Baer LA, Arts PJ, May FJ, Lehnig AC, Middelbeek RJW, Richard JJ, So K, Chen EY, Gao F, Narain NR, Distefano G, Shettigar VK, Hirshman MF, Ziolo MT, Kiebish MA, Tseng YH, Coen PM, Goodyear LJ. 12,13-diHOME: An Exercise-Induced Lipokine that Increases Skeletal Muscle Fatty Acid Uptake. Cell Metab 2018; 27:1111-1120.e3. [PMID: 29719226 PMCID: PMC5935136 DOI: 10.1016/j.cmet.2018.03.020] [Citation(s) in RCA: 173] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 02/06/2018] [Accepted: 03/29/2018] [Indexed: 01/08/2023]
Abstract
Circulating factors released from tissues during exercise have been hypothesized to mediate some of the health benefits of regular physical activity. Lipokines are circulating lipid species that have recently been reported to affect metabolism in response to cold. Here, lipidomics analysis revealed that a bout of moderate-intensity exercise causes a pronounced increase in the circulating lipid 12,13-dihydroxy-9Z-octadecenoic acid (12,13-diHOME) in male, female, young, old, sedentary, and active human subjects. In mice, both a single bout of exercise and exercise training increased circulating 12,13-diHOME and surgical removal of brown adipose tissue (BAT) negated the increase in 12,13-diHOME, suggesting that BAT is the tissue source for exercise-stimulated 12,13-diHOME. Acute 12,13-diHOME treatment of mice in vivo increased skeletal muscle fatty acid uptake and oxidation, but not glucose uptake. These data reveal that lipokines are novel exercise-stimulated circulating factors that may contribute to the metabolic changes that occur with physical exercise.
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Affiliation(s)
- Kristin I Stanford
- Dorothy M. Davis Heart and Lung Research Institute, Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, 460 W. 12(th) Avenue, Columbus, OH 43210, USA.
| | - Matthew D Lynes
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA
| | - Hirokazu Takahashi
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA
| | - Lisa A Baer
- Dorothy M. Davis Heart and Lung Research Institute, Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, 460 W. 12(th) Avenue, Columbus, OH 43210, USA
| | - Peter J Arts
- Dorothy M. Davis Heart and Lung Research Institute, Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, 460 W. 12(th) Avenue, Columbus, OH 43210, USA
| | - Francis J May
- Dorothy M. Davis Heart and Lung Research Institute, Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, 460 W. 12(th) Avenue, Columbus, OH 43210, USA
| | - Adam C Lehnig
- Dorothy M. Davis Heart and Lung Research Institute, Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, 460 W. 12(th) Avenue, Columbus, OH 43210, USA
| | - Roeland J W Middelbeek
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA
| | - Jeffrey J Richard
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA
| | - Kawai So
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA
| | | | - Fei Gao
- BERG, Framingham, MA 01701, USA
| | | | - Giovanna Distefano
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, FL 32827, USA
| | - Vikram K Shettigar
- Dorothy M. Davis Heart and Lung Research Institute, Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, 460 W. 12(th) Avenue, Columbus, OH 43210, USA
| | - Michael F Hirshman
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA
| | - Mark T Ziolo
- Dorothy M. Davis Heart and Lung Research Institute, Department of Physiology and Cell Biology, The Ohio State University Wexner Medical Center, 460 W. 12(th) Avenue, Columbus, OH 43210, USA
| | | | - Yu-Hua Tseng
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA
| | - Paul M Coen
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, Orlando, FL 32827, USA
| | - Laurie J Goodyear
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, One Joslin Place, Boston, MA 02215, USA.
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29
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Distefano G, Standley RA, Zhang X, Carnero EA, Yi F, Cornnell HH, Coen PM. Physical activity unveils the relationship between mitochondrial energetics, muscle quality, and physical function in older adults. J Cachexia Sarcopenia Muscle 2018; 9:279-294. [PMID: 29368427 PMCID: PMC5879963 DOI: 10.1002/jcsm.12272] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 09/01/2017] [Accepted: 10/24/2017] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND The concept of mitochondrial dysfunction in ageing muscle is highly controversial. In addition, emerging evidence suggests that reduced muscle oxidative capacity and efficiency underlie the aetiology of mobility loss in older adults. Here, we hypothesized that studying well-phenotyped older cohorts across a wide range of physical activity would unveil a range of mitochondrial function in skeletal muscle and in turn allow us to more clearly examine the impact of age per se on mitochondrial energetics. This also enabled us to more clearly define the relationships between mitochondrial energetics and muscle lipid content with clinically relevant assessments of muscle and physical function. METHODS Thirty-nine volunteers were recruited to the following study groups: young active (YA, n = 2 women/8 men, age = 31.2 ± 5.4 years), older active (OA, n = 2 women/8 men, age = 67.5 ± 2.7 years), and older sedentary (OS, n = 8 women/11 men, age = 70.7 ± 4.7 years). Participants completed a graded exercise test to determine fitness (VO2 peak), a submaximal exercise test to determine exercise efficiency, and daily physical activity was recorded using a tri-axial armband accelerometer. Mitochondrial energetics were determined by (i) 31 P magnetic resonance spectroscopy and (ii) respirometry of fibre bundles from vastus lateralis biopsies. Quadriceps function was assessed by isokinetic dynamometry and physical function by the short physical performance battery and stair climb test. RESULTS Daily physical activity energy expenditure was significantly lower in OS, compared with YA and OA groups. Despite fitness being higher in YA compared with OA and OS, mitochondrial respiration, maximum mitochondrial capacity, Maximal ATP production/Oxygen consumption (P/O) ratio, and exercise efficiency were similar in YA and OA groups and were significantly lower in OS. P/O ratio was correlated with exercise efficiency. Time to complete the stair climb and repeated chair stand tests were significantly greater for OS. Interestingly, maximum mitochondrial capacity was related to muscle contractile performance and physical function. CONCLUSIONS Older adults who maintain a high amount of physical activity have better mitochondrial capacity, similar to highly active younger adults, and this is related to their better muscle quality, exercise efficiency, and physical performance. This suggests that mitochondria could be an important therapeutic target for sedentary ageing associated conditions including sarcopenia, dynapenia, and loss of physical function.
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Affiliation(s)
- Giovanna Distefano
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, 301 East Princeton Street, Orlando, FL, 32804, USA
| | - Robert A Standley
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, 301 East Princeton Street, Orlando, FL, 32804, USA
| | - Xiaolei Zhang
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, 301 East Princeton Street, Orlando, FL, 32804, USA
| | - Elvis A Carnero
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, 301 East Princeton Street, Orlando, FL, 32804, USA
| | - Fanchao Yi
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, 301 East Princeton Street, Orlando, FL, 32804, USA
| | - Heather H Cornnell
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, 301 East Princeton Street, Orlando, FL, 32804, USA
| | - Paul M Coen
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, 301 East Princeton Street, Orlando, FL, 32804, USA.,Sanford Burnham Prebys Medical Discovery Institute at Lake Nona, 6400 Sanger Rd, Orlando, FL, 32827, USA
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Daemen S, van Polanen N, Hesselink MKC. The effect of diet and exercise on lipid droplet dynamics in human muscle tissue. ACTA ACUST UNITED AC 2018. [PMID: 29514886 DOI: 10.1242/jeb.167015] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The majority of fat in the human body is stored as triacylglycerols in white adipose tissue. In the obese state, adipose tissue mass expands and excess lipids are stored in non-adipose tissues, such as skeletal muscle. Lipids are stored in skeletal muscle in the form of small lipid droplets. Although originally viewed as dull organelles that simply store lipids as a consequence of lipid overflow from adipose tissue, lipid droplets are now recognized as key components in the cell that exert a variety of relevant functions in multiple tissues (including muscle). Here, we review the effect of diet and exercise interventions on myocellular lipid droplets and their putative role in insulin sensitivity from a human perspective. We also provide an overview of lipid droplet biology and identify gaps for future research.
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Affiliation(s)
- Sabine Daemen
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
| | - Nynke van Polanen
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
| | - Matthijs K C Hesselink
- Department of Human Biology and Human Movement Sciences, NUTRIM School for Nutrition and Translational Research in Metabolism, Maastricht University Medical Centre+, 6200MD Maastricht, The Netherlands
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Abstract
A substantial loss of muscle mass and strength (sarcopenia), a decreased regenerative capacity, and a compromised physical performance are hallmarks of aging skeletal muscle. These changes are typically accompanied by impaired muscle metabolism, including mitochondrial dysfunction and insulin resistance. A challenge in the field of muscle aging is to dissociate the effects of chronological aging per se on muscle characteristics from the secondary influence of lifestyle and disease processes. Remarkably, physical activity and exercise are well-established countermeasures against muscle aging, and have been shown to attenuate age-related decreases in muscle mass, strength, and regenerative capacity, and slow or prevent impairments in muscle metabolism. We posit that exercise and physical activity can influence many of the changes in muscle during aging, and thus should be emphasized as part of a lifestyle essential to healthy aging.
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Affiliation(s)
- Giovanna Distefano
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, Florida 32804
| | - Bret H Goodpaster
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, Florida 32804
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida 32827
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Toledo FGS, Johannsen DL, Covington JD, Bajpeyi S, Goodpaster B, Conley KE, Ravussin E. Impact of prolonged overfeeding on skeletal muscle mitochondria in healthy individuals. Diabetologia 2018; 61:466-475. [PMID: 29150696 PMCID: PMC5770194 DOI: 10.1007/s00125-017-4496-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 10/17/2017] [Indexed: 12/01/2022]
Abstract
AIMS/HYPOTHESES Reduced mitochondrial capacity in skeletal muscle has been observed in obesity and type 2 diabetes. In humans, the aetiology of this abnormality is not well understood but the possibility that it is secondary to the stress of nutrient overload has been suggested. To test this hypothesis, we examined whether sustained overfeeding decreases skeletal muscle mitochondrial content or impairs function. METHODS Twenty-six healthy volunteers (21 men, 5 women, age 25.3 ± 4.5 years, BMI 25.5 ± 2.4 kg/m2) underwent a supervised protocol consisting of 8 weeks of high-fat overfeeding (40% over baseline energy requirements). Before and after overfeeding, we measured systemic fuel oxidation by indirect calorimetry and performed skeletal muscle biopsies to measure mitochondrial gene expression, content and function in vitro. Mitochondrial function in vivo was measured by 31P NMR spectroscopy. RESULTS With overfeeding, volunteers gained 7.7 ± 1.8 kg (% change 9.8 ± 2.3). Overfeeding increased fasting NEFA, LDL-cholesterol and insulin concentrations. Indirect calorimetry showed a shift towards greater reliance on lipid oxidation. In skeletal muscle tissue, overfeeding increased ceramide content, lipid droplet content and perilipin-2 mRNA expression. Phosphorylation of AMP-activated protein kinase was decreased. Overfeeding increased mRNA expression of certain genes coding for mitochondrial proteins (CS, OGDH, CPT1B, UCP3, ANT1). Despite the stress of nutrient overload, mitochondrial content and mitochondrial respiration in muscle did not change after overfeeding. Similarly, overfeeding had no effect on either the emission of reactive oxygen species or on mitochondrial function in vivo. CONCLUSIONS/INTERPRETATION Skeletal muscle mitochondria are significantly resilient to nutrient overload. The lower skeletal muscle mitochondrial oxidative capacity in human obesity is likely to be caused by reasons other than nutrient overload per se. TRIAL REGISTRATION ClinicalTrials.gov NCT01672632.
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Affiliation(s)
- Frederico G S Toledo
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh School of Medicine, 200 Lothrop Street, BST W1054, Pittsburgh, PA, 15261, USA.
| | | | | | - Sudip Bajpeyi
- Pennington Biomedical Research Center, Baton Rouge, LA, USA
- Department of Kinesiology, University of Texas El Paso, El Paso, TX, USA
| | - Bret Goodpaster
- Translational Research Institute for Metabolism and Diabetes, Orlando, FL, USA
| | - Kevin E Conley
- University of Washington Medical Center, Seattle, WA, USA
| | - Eric Ravussin
- Pennington Biomedical Research Center, Baton Rouge, LA, USA
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Effects of Exercise Training Alone on Depot-Specific Body Fat Stores in Youth: Review of Recent Literature. Pediatr Exerc Sci 2018; 30:58-68. [PMID: 28556755 DOI: 10.1123/pes.2016-0275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The prevalence of childhood obesity has increased at an alarming rate. The increased obesity rate in pediatrics parallels the increased risks for developing metabolic abnormalities, such as insulin resistance, type 2 diabetes, and nonalcoholic fatty liver disease. In particular, the strong relationship between obesity and such health consequences is well explained by the excessive accumulation of depot-specific body adiposity, such as visceral adipose tissue, intrahepatic lipid content, intermuscular adipose tissue, and/or intramyocellular lipid content. Limited evidence suggests that both aerobic and resistance exercise alone, independent of weight loss, can be an effective therapeutic strategy for improving risk markers of metabolic abnormalities as well as inducing positive changes in depot-specific body adiposity in obese children and adolescents. However, the independent role of exercise alone (without calorie restriction) in body fat distribution is still unclear, and the results are less conclusive in pediatrics. In this brief review, the effects of aerobic and resistance exercise on depot-specific body adiposity changes in children and adolescents are discussed.
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Resistance training regulates gene expression of molecules associated with intramyocellular lipids, glucose signaling and fiber size in old rats. Sci Rep 2017; 7:8593. [PMID: 28819168 PMCID: PMC5561018 DOI: 10.1038/s41598-017-09343-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 07/17/2017] [Indexed: 11/08/2022] Open
Abstract
Sarcopenia is a complex multifactorial process, some of which involves fat infiltration. Intramyocellular lipid (IMCL) accumulation is postulated to play a role on sarcopenia during aging, which is believed to be due alterations in glucose homeostasis in the skeletal muscle. Sarcopenia, along with intramuscular lipids, is associated with physical inactivity. Resistance training (RT) has been indicated to minimize the age-induced muscle skeletal adaptations. Thus, we aimed to investigate the effects of RT on mRNA levels of regulatory components related to intramyocellular lipid, glucose metabolism and fiber size in soleus and gastrocnemius muscles of aged rats. Old male rats were submitted to RT (ladder climbing, progressive load, 3 times a week for 12 weeks). Age-induced accumulation of IMCL was attenuated by RT, which was linked to a PPARy-mediated mechanism, concomitant to enhanced regulatory components of glucose homeostasis (GLUT-4, G6PDH, Hk-2 and Gly-Syn-1). These responses were also linked to decreased catabolic (TNF-α, TWEAK/Fn14 axis; FOXO-1, Atrogin-1 and MuRF1; Myostatin) and increased anabolic intracellular pathways (IGF-1-mTOR-p70S6sk-1 axis; MyoD) in muscles of trained aged rats. Our results point out the importance of RT on modulation of gene expression of intracellular regulators related to age-induced morphological and metabolic adaptations in skeletal muscle.
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Distefano G, Standley RA, Dubé JJ, Carnero EA, Ritov VB, Stefanovic-Racic M, Toledo FGS, Piva SR, Goodpaster BH, Coen PM. Chronological Age Does not Influence Ex-vivo Mitochondrial Respiration and Quality Control in Skeletal Muscle. J Gerontol A Biol Sci Med Sci 2017; 72:535-542. [PMID: 27325231 DOI: 10.1093/gerona/glw102] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 05/17/2016] [Indexed: 12/20/2022] Open
Abstract
Background Considerable debate continues to surround the concept of mitochondrial dysfunction in aging muscle. We tested the overall hypothesis that age per se does not influence mitochondrial function and markers of mitochondria quality control, that is, expression of fusion, fission, and autophagy proteins. We also investigated the influence of cardiorespiratory fitness (VO2max) and adiposity (body mass index) on these associations. Methods Percutaneous biopsies of the vastus lateralis were obtained from sedentary young (n = 14, 24±3 years), middle-aged (n = 24, 41±9 years) and older adults (n = 20, 78±5 years). A physically active group of young adults (n = 10, 27±5 years) was studied as a control. Mitochondrial respiration was determined in saponin permeabilized fiber bundles. Fusion, fission and autophagy protein expression was determined by Western blot. Cardiorespiratory fitness was determined by a graded exercise test. Results Mitochondrial respiratory capacity and expression of fusion (OPA1 and MFN2) and fission (FIS1) proteins were not different among sedentary groups despite a wide age range (21 to 88 years). Mitochondrial respiratory capacity and fusion and fission proteins were, however, negatively associated with body mass index, and mitochondrial respiratory capacity was positively associated with cardiorespiratory fitness. The young active group had higher respiration, complex I and II respiratory control ratios, and expression of fusion and fission proteins. Finally, the expression of fusion, fission, and autophagy proteins were linked with mitochondrial respiration. Conclusions Mitochondrial respiration and markers of mitochondrial dynamics (fusion and fission) are not associated with chronological age per se, but rather are more strongly associated with body mass index and cardiorespiratory fitness.
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Affiliation(s)
- Giovanna Distefano
- Division of Endocrinology and Metabolism, Department of Medicine.,Department of Physical Therapy, University of Pittsburgh, Pennsylvania and
| | | | - John J Dubé
- Division of Endocrinology and Metabolism, Department of Medicine
| | - Elvis A Carnero
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando
| | - Vladimir B Ritov
- Division of Endocrinology and Metabolism, Department of Medicine
| | | | | | - Sara R Piva
- Department of Physical Therapy, University of Pittsburgh, Pennsylvania and
| | | | - Paul M Coen
- Division of Endocrinology and Metabolism, Department of Medicine
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Lipid droplet remodelling and reduced muscle ceramides following sprint interval and moderate-intensity continuous exercise training in obese males. Int J Obes (Lond) 2017; 41:1745-1754. [PMID: 28736444 DOI: 10.1038/ijo.2017.170] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Revised: 06/16/2017] [Accepted: 07/14/2017] [Indexed: 12/14/2022]
Abstract
BACKGROUND/OBJECTIVES In obesity, improved muscle insulin sensitivity following exercise training has been linked to the lowering of diacylglycerol (DAG) and ceramide concentrations. Little is known, however, about how improved insulin action with exercise training in obese individuals relates to lipid droplet (LD) adaptations in skeletal muscle. In this study we investigated the hypothesis that short-term sprint interval training (SIT) and moderate-intensity continuous training (MICT) in obese individuals would increase perilipin (PLIN) expression, increase the proportion of LDs in contact with mitochondria and reduce muscle concentrations of DAGs and ceramides. METHODS Sixteen sedentary obese males performed 4 weeks of either SIT (4-7 × 30 s sprints at 200% Wmax, 3 days week) or MICT (40-60 min cycling at ~65% VO2peak, 5 days per week), and muscle biopsies were obtained pre- and post-training. RESULTS Training increased PLIN2 (SIT 90%, MICT 68%) and PLIN5 (SIT 47%, MICT 34%) expression in type I fibres only, and increased PLIN3 expression in both type I (SIT 63%, MICT 67%) and type II fibres (SIT 70%, MICT 160%) (all P<0.05). Training did not change LD content but increased the proportion of LD in contact with mitochondria (SIT 12%, MICT 21%, P<0.01). Ceramides were reduced following training (SIT -10%, MICT -7%, P<0.05), but DAG was unchanged. No training × group interactions were observed for any variables. CONCLUSIONS These results confirm the hypothesis that SIT and MICT results in remodelling of LDs and lowers ceramide concentrations in skeletal muscle of sedentary obese males.
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Chow LS, Mashek DG, Wang Q, Shepherd SO, Goodpaster BH, Dubé JJ. Effect of acute physiological free fatty acid elevation in the context of hyperinsulinemia on fiber type-specific IMCL accumulation. J Appl Physiol (1985) 2017; 123:71-78. [PMID: 28450549 DOI: 10.1152/japplphysiol.00209.2017] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 04/22/2017] [Accepted: 04/22/2017] [Indexed: 12/22/2022] Open
Abstract
It is well described that increasing free fatty acids (FFAs) to high physiological levels reduces insulin sensitivity. In sedentary humans, intramyocellular lipid (IMCL) is inversely related to insulin sensitivity. Since muscle fiber composition affects muscle metabolism, whether FFAs induce IMCL accumulation in a fiber type-specific manner remains unknown. We hypothesized that in the setting of acute FFA elevation by lipid infusion within the context of a hyperinsulinemic-euglycemic clamp, IMCL will preferentially accumulate in type 1 fibers. Normal-weight participants (n = 57, mean ± SE: age 24 ± 0.6 yr, BMI 22.2 ± 0.3 kg/m2) who were either endurance trained or sedentary by self-report were recruited from the University of Minnesota (n = 31, n = 15 trained) and University of Pittsburgh (n = 26, n = 14 trained). All participants underwent a hyperinsulinemic-euglycemic clamp in the context of a 6-h infusion of either lipid or glycerol control. A vastus lateralis muscle biopsy was obtained at baseline and end-infusion (6 h). The muscle biopsies were processed and analyzed at the University of Pittsburgh for fiber type-specific IMCL accumulation by Oil-Red-O staining. Regardless of training status, acute elevation of FFAs to high physiological levels (~400-600 meq/l) increased IMCL preferentially in type 1 fibers (+35 ± 11% compared with baseline, +29 ± 11% compared with glycerol control: P < 0.05). The increase in IMCL correlated with a decline in insulin sensitivity as measured by the hyperinsulinemic-euglycemic clamp (r = -0.32, P < 0.01) independent of training status. Regardless of training status, increase of FFAs to a physiological range within the context of hyperinsulinemia shows preferential IMCL accumulation in type 1 fibers.NEW & NOTEWORTHY This novel human study examined the effects of FFA elevation in the setting of hyperinsulinemia on accumulation of fat in specific types of muscle fibers. Within the context of the hyperinsulinemic-euglycemic clamp, we found that an increase of FFAs to a physiological range sufficient to reduce insulin sensitivity is associated with preferential IMCL accumulation in type 1 fibers.
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Affiliation(s)
- Lisa S Chow
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota;
| | - Douglas G Mashek
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota
| | - Qi Wang
- Division of Biostatistics, School of Public Health, Minneapolis, Minnesota
| | - Sam O Shepherd
- Research Institute for Sport & Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom; and
| | - Bret H Goodpaster
- Department of Endocrinology, University of Pittsburgh Schools of the Health Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - John J Dubé
- Department of Endocrinology, University of Pittsburgh Schools of the Health Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania
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Dubé JJ, Broskey NT, Despines AA, Stefanovic-Racic M, Toledo FGS, Goodpaster BH, Amati F. Muscle Characteristics and Substrate Energetics in Lifelong Endurance Athletes. Med Sci Sports Exerc 2017; 48:472-80. [PMID: 26460630 DOI: 10.1249/mss.0000000000000789] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
PURPOSE The goal of this study was to explore the effect of lifelong aerobic exercise (i.e., chronic training) on skeletal muscle substrate stores (intramyocellular triglyceride [IMTG] and glycogen), skeletal muscle phenotypes, and oxidative capacity (ox), in older endurance-trained master athletes (OA) compared with noncompetitive recreational younger (YA) athletes matched by frequency and mode of training. METHODS Thirteen OA (64.8 ± 4.9 yr) exercising 5 times per week or more were compared with 14 YA (27.8 ± 4.9 yr) males and females. IMTG, glycogen, fiber types, succinate dehydrogenase, and capillarization were measured by immunohistochemistry in vastus lateralis biopsies. Fat-ox and carbohydrate (CHO)-ox were measured by indirect calorimetry before and after an insulin clamp and during a cycle ergometer graded maximal test. RESULTS V˙O2peak was lower in OA than YA. The OA had greater IMTG in all fiber types and lower glycogen stores than YA. This was reflected in greater proportion of type I and less type II fibers in OA. Type I fibers were similar in size, whereas type II fibers were smaller in OA compared with YA. Both groups had similar succinate dehydrogenase content. Numbers of capillaries per fiber were reduced in OA but with a higher number of capillaries per area. Metabolic flexibility and insulin sensitivity were similar in both groups. Exercise metabolic efficiency was higher in OA. At moderate exercise intensities, carbohydrate-ox was lower in OA but with similar Fat-ox. CONCLUSIONS Lifelong exercise is associated with higher IMTG content in all muscle fibers and higher metabolic efficiency during exercise that are not explained by differences in muscle fibers types and other muscle characteristics when comparing older with younger athletes matched by exercise mode and frequency.
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Affiliation(s)
- John J Dubé
- 1Division of Endocrinology and Metabolism, Department of Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, PA; and 2Department of Physiology & Institute of Sport Sciences, School of Biology and Medicine, University of Lausanne, Lausanne, SWITZERLAND
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The Flexibility of Ectopic Lipids. Int J Mol Sci 2016; 17:ijms17091554. [PMID: 27649157 PMCID: PMC5037826 DOI: 10.3390/ijms17091554] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 08/30/2016] [Accepted: 09/01/2016] [Indexed: 02/07/2023] Open
Abstract
In addition to the subcutaneous and the visceral fat tissue, lipids can also be stored in non-adipose tissue such as in hepatocytes (intrahepatocellular lipids; IHCL), skeletal (intramyocellular lipids; IMCL) or cardiac muscle cells (intracardiomyocellular lipids; ICCL). Ectopic lipids are flexible fuel stores that can be depleted by physical exercise and repleted by diet. They are related to obesity and insulin resistance. Quantification of IMCL was initially performed invasively, using muscle biopsies with biochemical and/or histological analysis. 1H-magnetic resonance spectroscopy (1H-MRS) is now a validated method that allows for not only quantifying IMCL non-invasively and repeatedly, but also assessing IHCL and ICCL. This review summarizes the current available knowledge on the flexibility of ectopic lipids. The available evidence suggests a complex interplay between quantitative and qualitative diet, fat availability (fat mass), insulin action, and physical exercise, all important factors that influence the flexibility of ectopic lipids. Furthermore, the time frame of the intervention on these parameters (short-term vs. long-term) appears to be critical. Consequently, standardization of physical activity and diet are critical when assessing ectopic lipids in predefined clinical situations.
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Hames KC, Coen PM, King WC, Anthony SJ, Stefanovic-Racic M, Toledo FG, Brown J, Helbling N, Dubé JJ, DeLany JP, Jakicic JJ, Goodpaster BH. Resting and exercise energy metabolism in weight-reduced adults with severe obesity. Obesity (Silver Spring) 2016; 24:1290-8. [PMID: 27129892 PMCID: PMC6455966 DOI: 10.1002/oby.21501] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 02/14/2016] [Indexed: 11/12/2022]
Abstract
OBJECTIVE To determine effects of physical activity (PA) with diet-induced weight loss on energy metabolism in adults with severe obesity. METHODS Adults with severe obesity (n = 11) were studied across 6 months of intervention, then compared with controls with less severe obesity (n = 7) or normal weight (n = 9). Indirect calorimetry measured energy metabolism during exercise and rest. Markers of muscle oxidation were determined by immunohistochemistry. Data were presented as medians. RESULTS The intervention induced 7% weight loss (P = 0.001) and increased vigorous PA by 24 min/wk (P = 0.02). During exercise, energy expenditure decreased, efficiency increased (P ≤ 0.03), and fatty acid oxidation (FAO) did not change. Succinate dehydrogenase increased (P = 0.001), but fiber type remained the same. Post-intervention subjects' resting metabolism remained similar to controls. Efficiency was lower in post-intervention subjects compared with normal-weight controls exercising at 25 W (P ≤ 0.002) and compared with all controls exercising at 60% VO2peak (P ≤ 0.019). Resting and exercise FAO of post-intervention subjects remained similar to adults with less severe obesity. Succinate dehydrogenase and fiber type were similar across all body weight statuses. CONCLUSIONS While metabolic adaptations to PA during weight loss occur in adults with severe obesity, FAO does not change. Resulting FAO during rest and exercise remains similar to adults with less severe obesity.
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Affiliation(s)
- Kazanna C. Hames
- Department of Health and Physical Activity, School of Education, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Endocrine Research Unit, Mayo Clinic, Rochester, MN 55905 USA
| | - Paul M. Coen
- Department of Health and Physical Activity, School of Education, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, FL 32804, USA
| | - Wendy C. King
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
| | - Steven J. Anthony
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Maja Stefanovic-Racic
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Frederico G.S. Toledo
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Jolene Brown
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Nicole Helbling
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - John J. Dubé
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - James P. DeLany
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - John J. Jakicic
- Department of Health and Physical Activity, School of Education, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Bret H. Goodpaster
- Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Translational Research Institute for Metabolism and Diabetes, Florida Hospital, Orlando, FL 32804, USA
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Hasegawa N, Fujie S, Kurihara T, Homma T, Sanada K, Sato K, Hamaoka T, Iemitsu M. Effects of habitual aerobic exercise on the relationship between intramyocellular or extramyocellular lipid content and arterial stiffness. J Hum Hypertens 2016; 30:606-12. [PMID: 27169824 DOI: 10.1038/jhh.2016.28] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/15/2016] [Accepted: 04/01/2016] [Indexed: 12/19/2022]
Abstract
The accumulation of intramyocellular lipid (IMCL) and extramyocellular lipid (EMCL) is associated with arterial stiffness in middle-aged and older adults. Habitual aerobic exercise induces the improvement of arterial stiffness with reduction in fat accumulation. However, the relationship between aerobic exercise-induced changes in muscular lipids and arterial stiffness remains unclear. The purpose of this study was to investigate whether habitual aerobic exercise-induced changes in IMCL and EMCL content would lead to an improvement of arterial stiffness. First, in a cross-sectional study, we investigated whether cardiorespiratory fitness level affects the association between IMCL or EMCL content and arterial stiffness in 60 middle-aged and older subjects (61.0±1.3 years). Second, in an intervention study, we examined whether aerobic exercise training-induced changes in IMCL and EMCL content are associated with a reduction in arterial stiffness in 18 middle-aged and older subjects (67.0±1.7 years). In the cross-sectional study, IMCL content was negatively correlated with brachial-ankle pulse wave velocity (baPWV) (r=-0.47, P<0.05), whereas EMCL content was positively correlated with baPWV (r=0.48, P<0.05) in the low-fitness group, but was not correlated in the high-fitness group. Furthermore, 8-week aerobic exercise training in older adults increased IMCL content and reduced EMCL content. The training-induced change in baPWV was negatively correlated with training-induced changes in IMCL but was positively correlated with training-induced changes in EMCL. These findings suggest that aerobic exercise training-induced changes in IMCL and EMCL content may be related to a reduction in arterial stiffness in middle-aged and older adults.
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Affiliation(s)
- N Hasegawa
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - S Fujie
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - T Kurihara
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - T Homma
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - K Sanada
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - K Sato
- Graduate School of Human Development and Environment, Hyogo University, Hyogo, Japan
| | - T Hamaoka
- Department of Sports Medicine for Health Promotion, Tokyo Medical University, Tokyo, Japan
| | - M Iemitsu
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
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Qi J, Yang B, Ren C, Fu J, Zhang J. Swimming Exercise Alleviated Insulin Resistance by Regulating Tripartite Motif Family Protein 72 Expression and AKT Signal Pathway in Sprague-Dawley Rats Fed with High-Fat Diet. J Diabetes Res 2016; 2016:1564386. [PMID: 27843952 PMCID: PMC5098085 DOI: 10.1155/2016/1564386] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/14/2016] [Accepted: 10/03/2016] [Indexed: 01/07/2023] Open
Abstract
We aimed to investigate whether swimming exercise could improve insulin resistance (IR) by regulating tripartite motif family protein 72 (TRIM72) expression and AKT signal pathway in rats fed with high-fat diet. Five-week-old rats were classified into 3 groups: standard diet as control (CON), high-fat diet (HFD), and HFD plus swimming exercise (Ex-HFD). After 8 weeks, glucose infusion rate (GIR), markers of oxidative stress, mRNA and protein expression of TRIM72, protein of IRS, p-AKTSer473, and AKT were determined in quadriceps muscles. Compared with HFD, the GIR, muscle SOD, and GSH-Px were significantly increased (p < 0.05, resp.), whereas muscle MDA and 8-OHdG levels were significantly decreased (p < 0.05 and p < 0.01) in Ex-HFD. Expression levels of TRIM72 mRNA and protein in muscles were significantly reduced (p < 0.05 and p < 0.01), whereas protein expression levels of IRS-1, p-AKTSer473, and AKT were significantly increased in Ex-HFD compared with HFD (p < 0.01, p < 0.01, and p < 0.05). These results suggest that an 8-week swimming exercise improves HFD-induced insulin resistance maybe through a reduction of TRIM72 in skeletal muscle and enhancement of AKT signal transduction.
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Affiliation(s)
- Jie Qi
- College of Physical Education, Shanghai Normal University, Shanghai 200234, China
| | - Bo Yang
- Department of Food Science and Nutrition, Zhejiang University, Hangzhou 310053, China
| | - Cailing Ren
- Rehabilitation College of Gannan Medical University, Jiangxi 341000, China
| | - Jian Fu
- College of Physical Education, Yangzhou University, Jiangsu 225009, China
| | - Jun Zhang
- College of Physical Education, Shanghai Normal University, Shanghai 200234, China
- *Jun Zhang:
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Hasegawa N, Kurihara T, Sato K, Homma T, Fujie S, Fujita S, Sanada K, Hamaoka T, Iemitsu M. Intramyocellular and Extramyocellular Lipids Are Associated With Arterial Stiffness. Am J Hypertens 2015; 28:1473-9. [PMID: 25911640 DOI: 10.1093/ajh/hpv041] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2014] [Accepted: 03/03/2015] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Obese and overweight patients are at increased risk of arterial stiffness, and visceral, epicardial and hepatic fat accumulation is associated with cardiovascular disease risk. In general, muscular lipids are stored either in interstitial adipose tissue (extramyocellular lipid (EMCL)) or in lipid droplets within muscle cells (intramyocellular lipid (IMCL)). However, the association between IMCL or EMCL content and arterial stiffness remains unclear. This cross-sectional study aimed to clarify this association. METHODS A total of 237 subjects (18-81 years) were enrolled in this study. The IMCL and EMCL contents of the right vastus lateralis muscle were evaluated by proton magnetic resonance spectroscopy. Arterial stiffness was estimated using brachial-ankle pulse wave velocity (baPWV). RESULTS There were significant correlations between baPWV and the contents of both IMCL (R = -0.23, P < 0.001) and EMCL (R = 0.53, P < 0.001) in all subjects. The baPWV negatively correlated with IMCL content (R = -0.45, P < 0.001) in females only. In contrast, significant positive correlations were observed between baPWV and EMCL content in both males (R = 0.59, P < 0.001) and females (R = 0.55, P < 0.001). IMCL and EMCL contents contributed independently to baPWV variation after adjustment for age, sex, body mass index, visceral and subcutaneous abdominal fat, upper and lower limb fat, blood pressure, heart rate, and lipid profiles. CONCLUSION These results suggest that IMCL and EMCL contents may be a risk factor for arterial stiffness, and this association differed with gender and age.
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Affiliation(s)
- Natsuki Hasegawa
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Toshiyuki Kurihara
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Koji Sato
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Toshiyuki Homma
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Shumpei Fujie
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Satoshi Fujita
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Kiyoshi Sanada
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Takafumi Hamaoka
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Motoyuki Iemitsu
- Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan.
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Glouzon BKJ, Barsalani R, Lagacé JC, Dionne IJ. Muscle mass and insulin sensitivity in postmenopausal women after 6-month exercise training. Climacteric 2015; 18:846-51. [DOI: 10.3109/13697137.2015.1083002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Ipavec-Levasseur S, Croci I, Choquette S, Byrne NM, Cowin G, O'Moore-Sullivan TM, Prins JB, Hickman IJ. Effect of 1-h moderate-intensity aerobic exercise on intramyocellular lipids in obese men before and after a lifestyle intervention. Appl Physiol Nutr Metab 2015; 40:1262-8. [PMID: 26575100 DOI: 10.1139/apnm-2015-0258] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Intramyocellular lipids (IMCL) are depleted in response to an acute bout of exercise in lean endurance-trained individuals; however, it is unclear whether changes in IMCL content are also seen in response to acute and chronic exercise in obese individuals. We used magnetic resonance spectroscopy in 18 obese men and 5 normal-weight controls to assess IMCL content before and after an hour of cycling at the intensity corresponding with each participant's maximal whole-body rate of fat oxidation (Fatmax). Fatmax was determined via indirect calorimetry during a graded exercise test on a cycle ergometer. The same outcome measures were reassessed in the obese group after a 16-week lifestyle intervention comprising dietary calorie restriction and exercise training. At baseline, IMCL content decreased in response to 1 h of cycling at Fatmax in controls (2.8 ± 0.4 to 2.0 ± 0.3 A.U., -39%, p = 0.02), but not in obese (5.4 ± 2.1 vs. 5.2 ± 2.2 A.U., p = 0.42). The lifestyle intervention lead to weight loss (-10.0 ± 5.4 kg, p < 0.001), improvements in maximal aerobic power (+5.2 ± 3.4 mL/(kg·min)), maximal fat oxidation rate (+0.19 ± 0.22 g/min), and a 29% decrease in homeostasis model assessment score (all p < 0.05). However, when the 1 h of cycling at Fatmax was repeated after the lifestyle intervention, there remained no observable change in IMCL (4.6 ± 1.8 vs. 4.6 ± 1.9 A.U., p = 0.92). In summary, there was no IMCL depletion in response to 1 h of cycling at moderate intensity either before or after the lifestyle intervention in obese men. An effective lifestyle intervention including moderate-intensity exercise training did not impact rate of utilisation of IMCL during acute exercise in obese men.
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Affiliation(s)
| | - Ilaria Croci
- a The University of Queensland Diamantina Institute, Brisbane, Australia.,b School of Human Movement and Nutrition Sciences, University of Queensland, Brisbane, Australia.,c Mater Research Institute, University of Queensland, Brisbane, Australia
| | - Stéphane Choquette
- d Faculty of Physical Education and Sports, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Nuala M Byrne
- e Bond Institute of Health and Sport, Bond University, Robina, Australia.,f Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
| | - Gary Cowin
- g Centre for Advanced Imaging, University of Queensland, Brisbane, Australia
| | - Trisha M O'Moore-Sullivan
- c Mater Research Institute, University of Queensland, Brisbane, Australia.,h Department of Diabetes and Endocrinology, Princess Alexandra Hospital, Brisbane, Australia
| | - Johannes B Prins
- c Mater Research Institute, University of Queensland, Brisbane, Australia
| | - Ingrid J Hickman
- a The University of Queensland Diamantina Institute, Brisbane, Australia.,c Mater Research Institute, University of Queensland, Brisbane, Australia
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46
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Redzic M, Powell DK, Thomas DT. Vitamin D status is related to intramyocellular lipid in older adults. Endocrine 2014; 47:854-61. [PMID: 24676758 PMCID: PMC4386577 DOI: 10.1007/s12020-014-0238-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 03/10/2014] [Indexed: 12/17/2022]
Abstract
Vitamin D and intramyocellular lipid (IMCL) both affect muscle function, but the relationship between vitamin D status and IMCL has not been established. To assess the relationship between vitamin D [measured as 25-hydroxy-vitamin-D (25(OH)D)] and IMCL, 20 community-dwelling adults between the ages of 65 and 85 were recruited. Serum 25(OH)D, and gastrocnemius IMCL and extramyocellular lipid (EMCL) were measured with magnetic resonance spectroscopy and fat ratio segmentation. A lifestyle questionnaire assessed physical activity. Muscle strength (1-repetition maximum) and physical function tests (timed up and go, timed sit to stand, four square step test, and gait speed) were also performed. Mean 25(OH)D was 37.9 ± 13.1 ng/mL with a range of 19-68 ng/mL. Soleus and gastrocnemius IMCL to water ratio was 1.04 ± 0.43 and 0.53 ± 0.22, respectively, but only gastrocnemius IMCL was correlated with 25(OH)D (R (2) = 0.39; p = 0.02). This relationship was independent of body mass index (p > 0.14), physical activity level (p > 0.08), and sex (p > 0.13). 25(OH)D did not correlate with EMCL (R (2) = 0.007; p = 0.78). The four square step test was the only performance or strength test correlated with 25(OH)D (R (2) = 0.26; p = 0.023). Muscle strength and physical function measures were not correlated with IMCL or EMCL. These data suggest that vitamin D status may influence gastrocnemius IMCL content independent of body mass and physical activity. Future studies should consider exploring whether vitamin D has an independent role in affecting muscle lipid metabolism and function.
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Affiliation(s)
- Maja Redzic
- Division of Clinical Nutrition, University of Kentucky, 900 South Limestone, 209H CTW Building, Lexington, KY 40536, USA
| | - David K. Powell
- Magnetic Resonance Imaging and Spectroscopy Center, University of Kentucky, Lexington, KY, USA
| | - D. Travis Thomas
- Division of Clinical Nutrition, University of Kentucky, 900 South Limestone, 209H CTW Building, Lexington, KY 40536, USA
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Li Y, Lee S, Langleite T, Norheim F, Pourteymour S, Jensen J, Stadheim HK, Storås TH, Davanger S, Gulseth HL, Birkeland KI, Drevon CA, Holen T. Subsarcolemmal lipid droplet responses to a combined endurance and strength exercise intervention. Physiol Rep 2014; 2:2/11/e12187. [PMID: 25413318 PMCID: PMC4255802 DOI: 10.14814/phy2.12187] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Muscle lipid stores and insulin sensitivity have a recognized association although the mechanism remains unclear. We investigated how a 12‐week supervised combined endurance and strength exercise intervention influenced muscle lipid stores in sedentary overweight dysglycemic subjects and normal weight control subjects (n = 18). Muscle lipid stores were measured by magnetic resonance spectroscopy (MRS), electron microscopy (EM) point counting, and direct EM lipid droplet measurements of subsarcolemmal (SS) and intramyofibrillar (IMF) regions, and indirectly, by deep sequencing and real‐time PCR of mRNA of lipid droplet‐associated proteins. Insulin sensitivity and VO2max increased significantly in both groups after 12 weeks of training. Muscle lipid stores were reduced according to MRS at baseline before and after the intervention, whereas EM point counting showed no change in LD stores post exercise, indicating a reduction in muscle adipocytes. Large‐scale EM quantification of LD parameters of the subsarcolemmal LD population demonstrated reductions in LD density and LD diameters. Lipid droplet volume in the subsarcolemmal LD population was reduced by ~80%, in both groups, while IMF LD volume was unchanged. Interestingly, the lipid droplet diameter (n = 10 958) distribution was skewed, with a lack of small diameter lipid droplets (smaller than ~200 nm), both in the SS and IMF regions. Our results show that the SS LD lipid store was sensitive to training, whereas the dominant IMF LD lipid store was not. Thus, net muscle lipid stores can be an insufficient measure for the effects of training. We have investigated the muscle storage lipids responses to exercise, finding that subsarcolemmal lipid droplets are reduced 80%. Interestingly, we find that the lipid droplet diameter distribution was skewed, with a marked lack of lipid droplets smaller than 200 nm.
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Affiliation(s)
- Yuchuan Li
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | - Sindre Lee
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | - Torgrim Langleite
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway Department of Endocrinology, Morbid Obesity and Preventive Medicine, Faculty of Medicine, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Frode Norheim
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | - Shirin Pourteymour
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | | | | | | | - Svend Davanger
- Department of Anatomy, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | - Hanne L Gulseth
- Department of Endocrinology, Morbid Obesity and Preventive Medicine, Faculty of Medicine, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Kåre I Birkeland
- Department of Endocrinology, Morbid Obesity and Preventive Medicine, Faculty of Medicine, Oslo University Hospital, University of Oslo, Oslo, Norway
| | - Christian A Drevon
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
| | - Torgeir Holen
- Department of Nutrition, Institute of Basic Medical Science, University of Oslo, Oslo, Norway
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Schlueter N, de Sterke A, Willmes DM, Spranger J, Jordan J, Birkenfeld AL. Metabolic actions of natriuretic peptides and therapeutic potential in the metabolic syndrome. Pharmacol Ther 2014; 144:12-27. [PMID: 24780848 DOI: 10.1016/j.pharmthera.2014.04.007] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 04/14/2014] [Indexed: 12/26/2022]
Abstract
Natriuretic peptides (NPs) are a group of peptide-hormones mainly secreted from the heart, signaling via c-GMP coupled receptors. NP are well known for their renal and cardiovascular actions, reducing arterial blood pressure as well as sodium reabsorption. Novel physiological functions have been discovered in recent years, including activation of lipolysis, lipid oxidation, and mitochondrial respiration. Together, these responses promote white adipose tissue browning, increase muscular oxidative capacity, particularly during physical exercise, and protect against diet-induced obesity and insulin resistance. Exaggerated NP release is a common finding in congestive heart failure. In contrast, NP deficiency is observed in obesity and in type-2 diabetes, pointing to an involvement of NP in the pathophysiology of metabolic disease. Based upon these findings, the NP system holds the potential to be amenable to therapeutical intervention against pandemic diseases such as obesity, insulin resistance, and arterial hypertension. Various therapeutic approaches are currently under development. This paper reviews the current knowledge on the metabolic effects of the NP system and discusses potential therapeutic applications.
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Affiliation(s)
- Nina Schlueter
- Department of Endocrinology, Diabetes and Nutrition, Center for Cardiovascular Research, Charité, University School of Medicine, Berlin, Germany
| | - Anita de Sterke
- Department of Endocrinology, Diabetes and Nutrition, Center for Cardiovascular Research, Charité, University School of Medicine, Berlin, Germany
| | - Diana M Willmes
- Department of Endocrinology, Diabetes and Nutrition, Center for Cardiovascular Research, Charité, University School of Medicine, Berlin, Germany
| | - Joachim Spranger
- Department of Endocrinology, Diabetes and Nutrition, Center for Cardiovascular Research, Charité, University School of Medicine, Berlin, Germany
| | - Jens Jordan
- Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany
| | - Andreas L Birkenfeld
- Department of Endocrinology, Diabetes and Nutrition, Center for Cardiovascular Research, Charité, University School of Medicine, Berlin, Germany.
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49
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Devries MC, Samjoo IA, Hamadeh MJ, McCready C, Raha S, Watt MJ, Steinberg GR, Tarnopolsky MA. Endurance training modulates intramyocellular lipid compartmentalization and morphology in skeletal muscle of lean and obese women. J Clin Endocrinol Metab 2013; 98:4852-62. [PMID: 24081737 DOI: 10.1210/jc.2013-2044] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
CONTEXT The accumulation of intramyocellular lipids (IMCLs) and mitochondrial dysfunction in skeletal muscle have been associated with insulin resistance in obesity. Endurance training (ET) increases mitochondrial content/activity and IMCL content in young, active men and women. We have previously shown that ET alters the size, number, and physical juxtaposition of IMCLs and mitochondria. OBJECTIVE The purpose of this study was to determine the effects of obesity and ET on mitochondrial function, IMCL content, and IMCL-mitochondria juxtaposition in sedentary lean and obese women. DESIGN, SETTING, SUBJECTS, INTERVENTION, AND MAIN OUTCOME MEASURES: Obese (n = 11) and lean (n = 12), sedentary women were recruited using local advertisements and underwent 12 weeks of ET in our training facility at McMaster University. Blood and muscle biopsy samples (vastus lateralis) were collected before and after ET to measure IMCL and mitochondrial ultrastructure, mitochondrial oxidative capacity, lipid oxidation capacity, and lipid metabolism by-products. RESULTS Obese women were insulin resistant (homeostasis model assessment of insulin resistance) compared with lean women. ET did not change body weight but increased mitochondrial oxidative and β-oxidation capacity in both groups. ET mediated reorganization of the muscle architecture, whereby IMCL content in the subsarcolemmal region was reduced with a concomitant increase in intermyofibrillar IMCLs. ET increased the percentage of IMCLs in direct contact with mitochondria and did not alter diacylglycerol and ceramide content in either group. CONCLUSIONS ET mediated positive changes in mitochondrial function and lipid oxidation and induced intracellular IMCL reorganization, which is reflective of greater IMCL turnover capacity in both lean and obese women.
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Affiliation(s)
- Michaela C Devries
- Departments of Pediatrics and Medicine, McMaster University, Neuromuscular Disease Clinic, Health Sciences Centre, Room 2H26, 1200 Main Street West, Hamilton, Ontario L8N 3Z5, Canada.
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50
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Coen PM, Hames KC, Leachman EM, DeLany JP, Ritov VB, Menshikova EV, Dubé JJ, Stefanovic-Racic M, Toledo FGS, Goodpaster BH. Reduced skeletal muscle oxidative capacity and elevated ceramide but not diacylglycerol content in severe obesity. Obesity (Silver Spring) 2013; 21:2362-71. [PMID: 23512750 PMCID: PMC4136513 DOI: 10.1002/oby.20381] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2012] [Accepted: 12/28/2012] [Indexed: 01/12/2023]
Abstract
OBJECTIVE The link between a reduced capacity for skeletal muscle mitochondrial fatty acid oxidation (FAO) and lipotoxicity in human insulin resistance has been the subject of intense debate. The objective of this study was to investigate whether reduced FAO is associated with elevated acyl CoA, ceramide, and diacylglycerol (DAG) in severely obese insulin resistant subjects. METHODS Muscle biopsies were conducted in lean (L, 22.6 ± 0.5 kg/m(2) , n = 8), Class I (CI, 32.1 ± 0.4 kg/m(2) , n = 7) and Class II&III obese (CII&III, 45.6 ± 1.1 kg/m(2) , n = 15) women for acyl CoA, sphingolipid and DAG profiling. Intramyocellular triglyceride (IMTG) content was determined by histology. FAO was assessed by incubating muscle homogenates with [1-C]palmitate and measuring CO2 production. Cardiolipin content was quantified as an index of mitochondrial content. Lipid metabolism proteins, DGAT1, PLIN5, and PNPLA2 were quantified in biopsy samples by western blot. RESULTS CII&III were more insulin resistant (HOMA-IR: 4.5 ± 0.5 vs. 1.1 ± 0.1, P < 0.001), and had lower FAO (∼58%, P = 0.007) and cardiolipin content (∼31%, P = 0.013) compared to L. IMTG was elevated in CI (P = 0.04) and CII&III (P = 0.04) compared to L. Sphingolipid content was higher in CII&III compared to L (13.6 ± 1.1 vs. 10.3 ± 0.5 pmol/mg, P = 0.031) whereas DAG content was not different among groups. DGAT1 was elevated in CII&III, and PLIN5 was elevated in CI compared to L. CONCLUSIONS Severe obesity is associated with reduced muscle oxidative capacity and occurs concomitantly with elevated IMTG, ceramide and insulin resistance.
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Affiliation(s)
- P M Coen
- Department of Health and Physical Activity, School of Education, University of Pittsburgh, Pittsburgh, PA 15213, USA; Division of Endocrinology and Metabolism, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
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