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Zhou M, Wei Y, Feng Y, Zhang S, Ma N, Wang K, Tan P, Zhao Y, Zhao J, Ma X. Arginine Regulates Skeletal Muscle Fiber Type Formation via mTOR Signaling Pathway. Int J Mol Sci 2024; 25:6184. [PMID: 38892371 PMCID: PMC11173221 DOI: 10.3390/ijms25116184] [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: 05/06/2024] [Revised: 05/28/2024] [Accepted: 05/31/2024] [Indexed: 06/21/2024] Open
Abstract
The composition of skeletal muscle fiber types affects the quality of livestock meat and human athletic performance and health. L-arginine (Arg), a semi-essential amino acid, has been observed to promote the formation of slow-twitch muscle fibers in animal models. However, the precise molecular mechanisms are still unclear. This study investigates the role of Arg in skeletal muscle fiber composition and mitochondrial function through the mTOR signaling pathway. In vivo, 4-week C56BL/6J male mice were divided into three treatment groups and fed a basal diet supplemented with different concentrations of Arg in their drinking water. The trial lasted 7 weeks. The results show that Arg supplementation significantly improved endurance exercise performance, along with increased SDH enzyme activity and upregulated expression of the MyHC I, MyHC IIA, PGC-1α, and NRF1 genes in the gastrocnemius (GAS) and quadriceps (QUA) muscles compared to the control group. In addition, Arg activated the mTOR signaling pathway in the skeletal muscle of mice. In vitro experiments using cultured C2C12 myotubes demonstrated that Arg elevated the expression of slow-fiber genes (MyHC I and Tnnt1) as well as mitochondrial genes (PGC-1α, TFAM, MEF2C, and NRF1), whereas the effects of Arg were inhibited by the mTOR inhibitor rapamycin. In conclusion, these findings suggest that Arg modulates skeletal muscle fiber type towards slow-twitch fibers and enhances mitochondrial functions by upregulating gene expression through the mTOR signaling pathway.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Xi Ma
- State Key Laboratory of Animal Nutrition and Feeding, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China; (M.Z.); (Y.W.); (Y.F.); (S.Z.); (N.M.); (K.W.); (P.T.); (Y.Z.); (J.Z.)
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Roberts MD, McCarthy JJ, Hornberger TA, Phillips SM, Mackey AL, Nader GA, Boppart MD, Kavazis AN, Reidy PT, Ogasawara R, Libardi CA, Ugrinowitsch C, Booth FW, Esser KA. Mechanisms of mechanical overload-induced skeletal muscle hypertrophy: current understanding and future directions. Physiol Rev 2023; 103:2679-2757. [PMID: 37382939 PMCID: PMC10625844 DOI: 10.1152/physrev.00039.2022] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 06/12/2023] [Accepted: 06/21/2023] [Indexed: 06/30/2023] Open
Abstract
Mechanisms underlying mechanical overload-induced skeletal muscle hypertrophy have been extensively researched since the landmark report by Morpurgo (1897) of "work-induced hypertrophy" in dogs that were treadmill trained. Much of the preclinical rodent and human resistance training research to date supports that involved mechanisms include enhanced mammalian/mechanistic target of rapamycin complex 1 (mTORC1) signaling, an expansion in translational capacity through ribosome biogenesis, increased satellite cell abundance and myonuclear accretion, and postexercise elevations in muscle protein synthesis rates. However, several lines of past and emerging evidence suggest that additional mechanisms that feed into or are independent of these processes are also involved. This review first provides a historical account of how mechanistic research into skeletal muscle hypertrophy has progressed. A comprehensive list of mechanisms associated with skeletal muscle hypertrophy is then outlined, and areas of disagreement involving these mechanisms are presented. Finally, future research directions involving many of the discussed mechanisms are proposed.
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Affiliation(s)
- Michael D Roberts
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - John J McCarthy
- Department of Physiology, College of Medicine, University of Kentucky, Lexington, Kentucky, United States
| | - Troy A Hornberger
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, Wisconsin, United States
| | - Stuart M Phillips
- Department of Kinesiology, McMaster University, Hamilton, Ontario, Canada
| | - Abigail L Mackey
- Institute of Sports Medicine Copenhagen, Department of Orthopedic Surgery, Copenhagen University Hospital-Bispebjerg and Frederiksberg, and Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Gustavo A Nader
- Department of Kinesiology and Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, Pennsylvania, United States
| | - Marni D Boppart
- Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States
| | - Andreas N Kavazis
- School of Kinesiology, Auburn University, Auburn, Alabama, United States
| | - Paul T Reidy
- Department of Kinesiology, Nutrition and Health, Miami University, Oxford, Ohio, United States
| | - Riki Ogasawara
- Healthy Food Science Research Group, Cellular and Molecular Biotechnology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Cleiton A Libardi
- MUSCULAB-Laboratory of Neuromuscular Adaptations to Resistance Training, Department of Physical Education, Federal University of São Carlos, São Carlos, Brazil
| | - Carlos Ugrinowitsch
- School of Physical Education and Sport, University of São Paulo, São Paulo, Brazil
| | - Frank W Booth
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, United States
| | - Karyn A Esser
- Department of Physiology and Aging, College of Medicine, University of Florida, Gainesville, Florida, United States
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Salimi K, Alvandi M, Saberi Pirouz M, Rakhshan K, Howatson G. Regulating eEF2 and eEF2K in skeletal muscle by exercise. Arch Physiol Biochem 2023:1-12. [PMID: 36633938 DOI: 10.1080/13813455.2023.2164898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 12/15/2022] [Accepted: 12/29/2022] [Indexed: 01/13/2023]
Abstract
Skeletal muscle is a flexible and adaptable tissue that strongly responds to exercise training. The skeletal muscle responds to exercise by increasing muscle protein synthesis (MPS) when energy is available. One of protein synthesis's major rate-limiting and critical regulatory steps is the translation elongation pathway. The process of translation elongation in skeletal muscle is highly regulated. It requires elongation factors that are intensely affected by various physiological stimuli such as exercise and the total available energy of cells. Studies have shown that exercise involves the elongation pathway by numerous signalling pathways. Since the elongation pathway, has been far less studied than the other translation steps, its comprehensive prospect and quantitative understanding remain in the dark. This study highlights the current understanding of the effect of exercise training on the translation elongation pathway focussing on the molecular factors affecting the pathway, including Ca2+, AMPK, PKA, mTORC1/P70S6K, MAPKs, and myostatin. We further discussed the mode and volume of exercise training intervention on the translation elongation pathway.What is the topic of this review? This review summarises the impacts of exercise training on the translation elongation pathway in skeletal muscle focussing on eEF2 and eEF2K.What advances does it highlight? This review highlights mechanisms and factors that profoundly influence the translation elongation pathway and argues that exercise might modulate the response. This review also combines the experimental observations focussing on the regulation of translation elongation during and after exercise. The findings widen our horizon to the notion of mechanisms involved in muscle protein synthesis (MPS) through translation elongation response to exercise training.
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Affiliation(s)
- Kia Salimi
- Department of Exercise Physiology, Faculty of Sport and Exercise Sciences, University of Tehran, Tehran, Iran
| | - Masoomeh Alvandi
- Department of Biological Science in Sport and Health, University of Shahid Beheshti, Tehran, Iran
| | - Mahdi Saberi Pirouz
- Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
| | - Kamran Rakhshan
- Department of Medical Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Electrophysiology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Glyn Howatson
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
- Water Research Group, North West University, Potchefstroom, South Africa
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Alcohol, Resistance Exercise, and mTOR Pathway Signaling: An Evidence-Based Narrative Review. Biomolecules 2022; 13:biom13010002. [PMID: 36671386 PMCID: PMC9855961 DOI: 10.3390/biom13010002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 12/14/2022] [Accepted: 12/17/2022] [Indexed: 12/24/2022] Open
Abstract
Skeletal muscle mass is determined by the balance between muscle protein synthesis (MPS) and degradation. Several intracellular signaling pathways control this balance, including mammalian/mechanistic target of rapamycin (mTOR) complex 1 (C1). Activation of this pathway in skeletal muscle is controlled, in part, by nutrition (e.g., amino acids and alcohol) and exercise (e.g., resistance exercise (RE)). Acute and chronic alcohol use can result in myopathy, and evidence points to altered mTORC1 signaling as a contributing factor. Moreover, individuals who regularly perform RE or vigorous aerobic exercise are more likely to use alcohol frequently and in larger quantities. Therefore, alcohol may antagonize beneficial exercise-induced increases in mTORC1 pathway signaling. The purpose of this review is to synthesize up-to-date evidence regarding mTORC1 pathway signaling and the independent and combined effects of acute alcohol and RE on activation of the mTORC1 pathway. Overall, acute alcohol impairs and RE activates mTORC1 pathway signaling; however, effects vary by model, sex, feeding, training status, quantity, etc., such that anabolic stimuli may partially rescue the alcohol-mediated pathway inhibition. Likewise, the impact of alcohol on RE-induced mTORC1 pathway signaling appears dependent on several factors including nutrition and sex, although many questions remain unanswered. Accordingly, we identify gaps in the literature that remain to be elucidated to fully understand the independent and combined impacts of alcohol and RE on mTORC1 pathway signaling.
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Tian S, Ding M, Sun H. The effects of resistance exercise on body composition and physical function in prostate cancer patients undergoing androgen deprivation therapy: an update systematic review and meta-analysis. Aging Male 2022; 25:281-292. [PMID: 36382930 DOI: 10.1080/13685538.2022.2146670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
OBJECTIVE The aim of the meta-analysis was to explore effects of resistance exercise (RE) on body composition and physical function in patients with prostate cancer (PCa). DATA SOURCES We searched the electronic databases of Pubmed, Embase, Cochrane, and web of science. Published studies have been collected from these databases. Search terms include resistance training, strength training, RE, androgen suppression therapy, androgen deprivation therapy and PCa, with a deadline of 31 March 2022. MAIN RESULTS These studies showed significant improvements of body composition(Lean body mass MD: 1.12 95% CI [0.48, 1.76], p < 0.01; Body fat rate MD: -1.12 95% CI [-1.99,-0.24], p < 0.05; Appendicular skeletal mass MD: 0.74 95% CI [0.45, 1.03], p < 0.01) and physical function (leg press MD: 77.95 95% CI [38.90, 117.00], p < 0.01; stair climb MD:-0.30 95% CI [-0.49, -0.12], p < 0.01). In addition, the improvement of Body fat mass (MD: -0.21 95% CI [-0.79, 0.37], p > 0.05), 400 m walk (MD: -21.74 95% CI [-45.53, 2.05], p > 0.05) and times up and go (MD: -0.50 95% CI [-1.03, 0.03], p > 0.05) were not obvious. Subgroup analyses showed that RE for ≥ 6 months (compared with RE intervention for < 6 months) and starting exercise immediately after androgen deprivation therapy (ADT) (compared with delayed exercise after ADT) resulted in more significant improvements in body composition. Furthermore, the results showed that the exercise intensity of 8-12 RM significantly improved body composition. CONCLUSIONS RE seems to be a promising approach in order to improve body composition and physical function in PCa patients to offset their treatment-related side effects. RE should be used as a means of rehabilitation and care for PCa. Starting exercise immediately after ADT and extending exercise time while choosing the right intensity can better improve the patients' body composition and function. REGISTRATION NUMBER INPLASY202280019.
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Affiliation(s)
- Siyu Tian
- College of Physical Education, Shandong Normal University, Jinan, China
| | - Meng Ding
- College of Physical Education, Shandong Normal University, Jinan, China
| | - Hongfu Sun
- Institute of Great Health Products Research, Shandong Academy of Chinese Medicine, Jinan, China
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Horwath O, Edman S, Andersson A, Larsen FJ, Apró W. THRIFTY: a novel high-throughput method for rapid fibre type identification of isolated skeletal muscle fibres. J Physiol 2022; 600:4421-4438. [PMID: 36069036 PMCID: PMC9825974 DOI: 10.1113/jp282959] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 08/25/2022] [Indexed: 01/11/2023] Open
Abstract
Fibre type-specific analyses are required for broader understanding of muscle physiology, but such analyses are difficult to conduct due to the extreme time requirements of dissecting and fibre typing individual fibres. Investigations are often confined to a small number of fibres from few participants with low representativeness of the entire fibre population and the participant population. To increase the feasibility of conducting large-scale fibre type-specific studies, a valid and rapid method for high-throughput fibre typing of individually dissected fibres was developed and named THRIFTY (for high-THRoughput Immunofluorescence Fibre TYping). Employing THRIFTY, 400 fibre segments were fixed onto microscope slides with a pre-printed coordinated grid system, probed with antibodies against myosin heavy chain (MyHC)-I and MyHC-II and classified using a fluorescence microscope. The validity and speed of THRIFTY was compared to a previously validated protocol (dot blot) on a fibre-to-fibre basis. Fibre pool purity was evaluated using 'gold standard' SDS-PAGE and silver staining. A modified THRIFTY-protocol using fluorescence western blot equipment was also validated. THRIFTY displayed excellent agreement with the dot blot protocol, κ = 0.955 (95% CI: 0.928, 0.982), P < 0.001. Both the original and modified THRIFTY protocols generated type I and type II fibre pools of absolute purity. Using THRIFTY, 400 fibres were typed just under 11 h, which was approximately 3 times faster than dot blot. THRIFTY is a novel and valid method with high versatility for very rapid fibre typing of individual fibres. THRIFTY can therefore facilitate the generation of large fibre pools for more extensive mechanistic studies into skeletal muscle physiology. KEY POINTS: Skeletal muscle is composed of different fibre types, each with distinct physiological properties. To fully understand how skeletal muscle adapts to external cues such as exercise, nutrition and ageing, fibre type-specific investigations are required. Such investigations are very difficult to conduct due to the extreme time requirements related to classifying individually isolated muscle fibres. To bypass this issue, we have developed a rapid and reliable method named THRIFTY which is cheap as well as versatile and which can easily be implemented in most laboratories. THRIFTY increases the feasibility of conducting larger fibre type-specific studies and enables time-sensitive assays where measurements need to be carried out in close connection with tissue sampling. By using THRIFTY, new insights into fibre type-specific muscle physiology can be gained which may have broad implications in health and disease.
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Affiliation(s)
- Oscar Horwath
- Department of PhysiologyNutrition and BiomechanicsÅstrand LaboratorySwedish School of Sport and Health SciencesStockholmSweden
| | - Sebastian Edman
- Department of PhysiologyNutrition and BiomechanicsÅstrand LaboratorySwedish School of Sport and Health SciencesStockholmSweden
| | - Alva Andersson
- Department of PhysiologyNutrition and BiomechanicsÅstrand LaboratorySwedish School of Sport and Health SciencesStockholmSweden
| | - Filip J. Larsen
- Department of PhysiologyNutrition and BiomechanicsÅstrand LaboratorySwedish School of Sport and Health SciencesStockholmSweden
| | - William Apró
- Department of PhysiologyNutrition and BiomechanicsÅstrand LaboratorySwedish School of Sport and Health SciencesStockholmSweden,Department of Clinical ScienceIntervention and TechnologyKarolinska InstitutetStockholmSweden
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Morales-Scholz MG, Wette SG, Stokie JR, Tepper BT, Swinton C, Hamilton DL, Dwyer KM, Murphy RM, Howlett KF, Shaw CS. Muscle fiber type-specific autophagy responses following an overnight fast and mixed meal ingestion in human skeletal muscle. Am J Physiol Endocrinol Metab 2022; 323:E242-E253. [PMID: 35793481 DOI: 10.1152/ajpendo.00015.2022] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The aim of the present study was to investigate the fiber type-specific abundance of autophagy-related proteins after an overnight fast and following ingestion of a mixed meal in human skeletal muscle. Twelve overweight, healthy young male volunteers underwent a 3-h mixed meal tolerance test following an overnight fast. Blood samples were collected in the overnight-fasted state and throughout the 180-min postmeal period. Skeletal muscle biopsies were collected in the fasted state, and at 30 and 90 min after meal ingestion. Protein content of key autophagy markers and upstream signaling responses were measured in whole muscle and pooled single fibers using immunoblotting. In the fasted state, type I fibers displayed lower LC3B-I but higher LC3B-II abundance and higher LC3B-II/LC3B-I ratio compared with type II fibers (P < 0.05). However, there were no fiber type differences in p62/SQSTM1, unc-51 like autophagy activating kinase (ULK1), ATG5, or ATG12 (P > 0.05). Compared with the fasted state, there was a reduction in LC3B-II abundance, indicative of lower autophagosome content, in whole muscle and in both type I and type II fibers following meal ingestion (P < 0.05). This reduction in autophagosome content occurred alongside similar increases in p-AktS473 and p-mTORS2448 in both type I and type II muscle fibers (P < 0.05). In human skeletal muscle, type I fibers have a greater autophagosome content than type II fibers in the overnight-fasted state despite comparable abundance of other key upstream autophagy proteins. Autophagy is rapidly inhibited in both fiber types following the ingestion of a mixed meal.NEW & NOTEWORTHY This study examined the fiber type-specific content of key autophagy proteins in human muscle. We showed that markers of autophagosome content are higher in type I fibers in the overnight-fasted state, whereas autophagy is rapidly inhibited in both type I and type II fibers after the ingestion of a mixed meal.
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Affiliation(s)
- María G Morales-Scholz
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
- Human Movement Sciences Research Center (CIMOHU), University of Costa Rica, San José, Costa Rica
| | - Stefan G Wette
- Department of Biochemistry and Chemistry, School of Agriculture, Biomedicine and Environment (SABE), La Trobe University, Melbourne, Australia
| | - Jayden R Stokie
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Bianca T Tepper
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Courtney Swinton
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - David L Hamilton
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Karen M Dwyer
- School of Medicine, Deakin University, Geelong, Australia
| | - Robyn M Murphy
- Department of Biochemistry and Chemistry, School of Agriculture, Biomedicine and Environment (SABE), La Trobe University, Melbourne, Australia
| | - Kirsten F Howlett
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
| | - Christopher S Shaw
- Institute for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Geelong, Australia
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Hodson N, Mazzulla M, Holowaty MNH, Kumbhare D, Moore DR. RPS6 phosphorylation occurs to a greater extent in the periphery of human skeletal muscle fibers, near focal adhesions, after anabolic stimuli. Am J Physiol Cell Physiol 2021; 322:C94-C110. [PMID: 34852208 DOI: 10.1152/ajpcell.00357.2021] [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
Following anabolic stimuli (mechanical loading and/or amino acid provision) the mechanistic target of rapamycin complex 1 (mTORC1), a master regulator of protein synthesis, translocates toward the cell periphery. However, it is unknown if mTORC1-mediated phosphorylation events occur in these peripheral regions or prior to translocation (i.e. in central regions). We therefore aimed to determine the cellular location of a mTORC1-mediated phosphorylation event, RPS6Ser240/244, in human skeletal muscle following anabolic stimuli. Fourteen young, healthy males either ingested a protein-carbohydrate beverage (0.25g/kg protein, 0.75g/kg carbohydrate) alone (n=7;23±5yrs;76.8±3.6kg;13.6±3.8%BF, FED) or following a whole-body resistance exercise bout (n=7;22±2yrs;78.1±3.6kg;12.2±4.9%BF, EXFED). Vastus lateralis muscle biopsies were obtained at rest (PRE) and 120 and 300min following anabolic stimuli. RPS6Ser240/244 phosphorylation measured by immunofluorescent staining or immunoblot was positively correlated (r=0.76, p<0.001). Peripheral staining intensity of p-RPS6Ser240/244 increased above PRE in both FED and EXFED at 120min (~54% and ~138% respectively, p<0.05) but was greater in EXFED at both post-stimuli time points (p<0.05). The peripheral-central ratio of p-RPS6240/244 staining displayed a similar pattern, even when corrected for total RPS6 distribution, suggesting RPS6 phosphorylation occurs to a greater extent in the periphery of fibers. Moreover, p-RPS6Ser240/244 intensity within paxillin-positive regions, a marker of focal adhesion complexes, was elevated at 120min irrespective of stimulus (p=0.006) before returning to PRE at 300min. These data confirm that RPS6Ser240/244 phosphorylation occurs in the region of human muscle fibers to which mTOR translocates following anabolic stimuli and identifies focal adhesion complexes as a potential site of mTORC1 regulation in vivo.
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Affiliation(s)
- Nathan Hodson
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
| | - Michael Mazzulla
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
| | - Maksym N H Holowaty
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
| | | | - Daniel R Moore
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
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Grgic J, Schoenfeld BJ, Mikulic P. Effects of plyometric vs. resistance training on skeletal muscle hypertrophy: A review. JOURNAL OF SPORT AND HEALTH SCIENCE 2021; 10:530-536. [PMID: 32579911 PMCID: PMC8500805 DOI: 10.1016/j.jshs.2020.06.010] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 05/05/2020] [Accepted: 06/03/2020] [Indexed: 05/03/2023]
Abstract
OBJECTIVE In this review, we critically evaluate studies directly comparing the effects of plyometric vs. resistance training on skeletal muscle hypertrophy. METHODS We conducted electronic searches of PubMed/MEDLINE, Scopus, SPORTDiscus, and Web of Science to find studies that explored the effects of plyometric vs. resistance training on muscle hypertrophy. RESULTS Eight relevant studies were included in the review. Six studies compared the effects of plyometric vs. resistance training on muscle hypertrophy, while 2 studies explored the effects of combining plyometric and resistance training vs. isolated resistance training on acute anabolic signaling or muscle hypertrophy. Based on the results of these studies, we conclude that plyometric and resistance training may produce similar effects on whole muscle hypertrophy for the muscle groups of the lower extremities. Therefore, it seems that plyometric training has a greater potential for inducing increases in muscle size than previously thought. Despite the findings observed at the whole muscle level, the evidence for the effects of plyometric training on hypertrophy on the muscle fiber level is currently limited for drawing inferences. Compared to isolated resistance training, combining plyometric and resistance exercise does not seem to produce additive effects on anabolic signaling or muscle growth; however, this area requires future study. The limitations of the current body of evidence are that the findings are specific to (a) musculature of the lower extremities, (b) short-term training interventions that lasted up to 12 weeks, and (c) previously untrained or recreationally active participants. CONCLUSION This review highlights that plyometric and resistance training interventions may produce similar effects on whole muscle hypertrophy, at least for the muscle groups of the lower extremities, in untrained and recreationally trained individuals, and over short-term (i.e., ≤12 weeks) intervention periods.
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Affiliation(s)
- Jozo Grgic
- Institute for Health and Sport (IHES), Victoria University, Melbourne, VIC 3011, Australia.
| | | | - Pavle Mikulic
- Faculty of Kinesiology, University of Zagreb, Zagreb 10000, Croatia
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10
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Hokken R, Laugesen S, Aagaard P, Suetta C, Frandsen U, Ørtenblad N, Nielsen J. Subcellular localization- and fibre type-dependent utilization of muscle glycogen during heavy resistance exercise in elite power and Olympic weightlifters. Acta Physiol (Oxf) 2021; 231:e13561. [PMID: 32961628 DOI: 10.1111/apha.13561] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2020] [Revised: 09/13/2020] [Accepted: 09/14/2020] [Indexed: 12/16/2022]
Abstract
AIM Glycogen particles are found in different subcellular localizations, which are utilized heterogeneously in different fibre types during endurance exercise. Although resistance exercise typically involves only a moderate use of mixed muscle glycogen, the hypothesis of the present study was that high-volume heavy-load resistance exercise would mediate a pattern of substantial glycogen depletion in specific subcellular localizations and fibre types. METHODS 10 male elite weightlifters performed resistance exercise consisting of four sets of five (4 × 5) repetitions at 75% of 1RM back squats, 4 × 5 at 75% of 1RM deadlifts and 4 × 12 at 65% of 1RM rear foot elevated split squats. Muscle biopsies (vastus lateralis) were obtained before and after the exercise session. The volumetric content of intermyofibrillar (between myofibrils), intramyofibrillar (within myofibrils) and subsarcolemmal glycogen was assessed by transmission electron microscopy. RESULTS After exercise, biochemically determined muscle glycogen decreased by 38 (31:45)%. Location-specific glycogen analyses revealed in type 1 fibres a large decrement in intermyofibrillar glycogen, but no or only minor changes in intramyofibrillar or subsarcolemmal glycogen. In type 2 fibres, large decrements in glycogen were observed in all subcellular localizations. Notably, a substantial fraction of the type 2 fibres demonstrated near-depleted levels of intramyofibrillar glycogen after the exercise session. CONCLUSION Heavy resistance exercise mediates a substantial utilization of glycogen from all three subcellular localization in type 2 fibres, while mostly taxing intermyofibrillar glycogen stores in type 1 fibres. Thus, a better understanding of the impact of resistance training on myocellular metabolism and performance requires a focus on compartmentalized glycogen utilization.
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Affiliation(s)
- Rune Hokken
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
| | - Simon Laugesen
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
| | - Per Aagaard
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
| | - Charlotte Suetta
- Geriatric Research Unit Department of Geriatrics Bispebjerg‐Frederiksberg and Herlev‐Gentofte HospitalsUniversity of Copenhagen Kobenhavn Denmark
| | - Ulrik Frandsen
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
| | - Niels Ørtenblad
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
| | - Joachim Nielsen
- Department of Sports Science and Clinical Biomechanics University of Southern Denmark Odense M Denmark
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11
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Tobias IS, Galpin AJ. Moving human muscle physiology research forward: an evaluation of fiber type-specific protein research methodologies. Am J Physiol Cell Physiol 2020; 319:C858-C876. [DOI: 10.1152/ajpcell.00107.2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Human skeletal muscle is a heterogeneous tissue composed of multiple fiber types that express unique contractile and metabolic properties. While analysis of mixed fiber samples predominates and holds value, increasing attention has been directed toward studying proteins segregated by fiber type, a methodological distinction termed “fiber type-specific.” Fiber type-specific protein studies have the advantage of uncovering key molecular effects that are often missed in mixed fiber homogenate studies but also require greater time and resource-intensive methods, particularly when applied to human muscle. This review summarizes and compares current methods used for fiber type-specific protein analysis, highlighting their advantages and disadvantages for human muscle studies, in addition to recent advances in these techniques. These methods can be grouped into three categories based on the initial processing of the tissue: 1) muscle-specific fiber homogenates, 2) cross sections of fiber bundles, and 3) isolated single fibers, with various subtechniques for performing fiber type identification and protein quantification. The relative implementation for each unique methodological approach is analyzed from 83 fiber type-specific studies of proteins in live human muscle found in the literature to date. These studies have investigated several proteins involved in a wide range of cellular functions that are important to muscle tissue. The second half of this review summarizes key findings from this ensemble of fiber type-specific human protein studies. We highlight examples of where this analytical approach has helped to improve understanding of important physiological topics such as insulin sensitivity, muscle hypertrophy, muscle fatigue, and adaptation to different exercise programs.
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Affiliation(s)
- Irene S. Tobias
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
| | - Andrew J. Galpin
- Biochemistry and Molecular Exercise Physiology Laboratory, Center for Sport Performance, California State University, Fullerton, California
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12
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Mirzoev TM. Skeletal Muscle Recovery from Disuse Atrophy: Protein Turnover Signaling and Strategies for Accelerating Muscle Regrowth. Int J Mol Sci 2020; 21:ijms21217940. [PMID: 33114683 PMCID: PMC7663166 DOI: 10.3390/ijms21217940] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 10/08/2020] [Accepted: 10/23/2020] [Indexed: 12/15/2022] Open
Abstract
Skeletal muscle fibers have a unique capacity to adjust their metabolism and phenotype in response to alternations in mechanical loading. Indeed, chronic mechanical loading leads to an increase in skeletal muscle mass, while prolonged mechanical unloading results in a significant decrease in muscle mass (muscle atrophy). The maintenance of skeletal muscle mass is dependent on the balance between rates of muscle protein synthesis and breakdown. While molecular mechanisms regulating protein synthesis during mechanical unloading have been relatively well studied, signaling events implicated in protein turnover during skeletal muscle recovery from unloading are poorly defined. A better understanding of the molecular events that underpin muscle mass recovery following disuse-induced atrophy is of significant importance for both clinical and space medicine. This review focuses on the molecular mechanisms that may be involved in the activation of protein synthesis and subsequent restoration of muscle mass after a period of mechanical unloading. In addition, the efficiency of strategies proposed to improve muscle protein gain during recovery is also discussed.
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Affiliation(s)
- Timur M Mirzoev
- Myology Laboratory, Institute of Biomedical Problems RAS, Moscow 123007, Russia
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Horwath O, Moberg M, Larsen FJ, Philp A, Apró W, Ekblom B. Influence of sex and fiber type on the satellite cell pool in human skeletal muscle. Scand J Med Sci Sports 2020; 31:303-312. [DOI: 10.1111/sms.13848] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Revised: 09/22/2020] [Accepted: 09/24/2020] [Indexed: 01/08/2023]
Affiliation(s)
- Oscar Horwath
- Department of Physiology, Nutrition and Biomechanics Åstrand Laboratory Swedish School of Sport and Health Sciences Stockholm Sweden
| | - Marcus Moberg
- Department of Physiology, Nutrition and Biomechanics Åstrand Laboratory Swedish School of Sport and Health Sciences Stockholm Sweden
| | - Filip J. Larsen
- Department of Physiology, Nutrition and Biomechanics Åstrand Laboratory Swedish School of Sport and Health Sciences Stockholm Sweden
| | - Andrew Philp
- Diabetes and Metabolism Division Garvan Institute of Medical Research Darlinghurst, Sydney NSW Australia
- St Vincent’s Medical School UNSW Medicine UNSW Sydney Sydney Australia
| | - William Apró
- Department of Physiology, Nutrition and Biomechanics Åstrand Laboratory Swedish School of Sport and Health Sciences Stockholm Sweden
- Department of Clinical Science, Intervention and Technology Karolinska Institutet Stockholm Sweden
| | - Björn Ekblom
- Department of Physiology, Nutrition and Biomechanics Åstrand Laboratory Swedish School of Sport and Health Sciences Stockholm Sweden
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14
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Logan L, Toohey K, Kavanagh PS, Paterson C, McKune AJ. The Effect of Exercise on Body Composition and Physical Performance in Prostate Cancer Patients Undergoing Androgen Deprivation Therapy (ADT): A Narrative Synthesis. Semin Oncol Nurs 2020; 36:151067. [PMID: 33010982 DOI: 10.1016/j.soncn.2020.151067] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE This review sought to synthesize evidence examining the effect of exercise on prostate cancer patients undergoing androgen deprivation therapy (ADT). DATA SOURCES A systematic literature search was conducted in electronic databases (CINAHL, MEDLINE, APA PsychINFO, Scopus, SPORTDiscus, and Cochrane Library) from their inception to March 31, 2020. Inclusion criteria were randomized controlled trials (RCTs) testing the effect of exercise on body composition, muscle strength and physical performance. Fourteen RCTs were included. Participant numbers within the individual RCTs ranged from 19 to 163 with heterogeneity in prostate cancer stage (localized and locally advanced diagnoses) with age of participants ranging from 43 to 90 years. The length of the interventions ranged from 12 weeks to 12 months, with the number of sessions per week ranging from 2 to 5. Resistance training intensity ranged from 60% to 90% 1RM and the aerobic training ranged from 60% to 90% HRmax. CONCLUSIONS Resistance training and sport (football) in the form of small sided games (SSGs) played an important role in preserving bone mineral density and lean mass as well as improving muscle strength and physical performance outcomes in men affected by prostate cancer undergoing ADT. IMPLICATIONS FOR NURSING PRACTICE Multimodal exercise, including resistance exercise and activity that includes repeated sprints (SSGs), benefit the maintenance of bone mineral density and lean mass as well as increase strength and physical performance in men affected by prostate cancer undergoing ADT. Based on this evidence, nurses should coordinate timely referrals to qualified exercise physiologists or physiotherapist with expertise in cancer care.
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Affiliation(s)
- Lucas Logan
- Faculty of Health, University of Canberra, Canberra, Australia
| | - Kellie Toohey
- Faculty of Health, University of Canberra, Canberra, Australia; Prehabilitation, Activity, Cancer, Exercise, Survivorship (PACES) Research Group, University of Canberra, Canberra, Australia
| | - Phillip S Kavanagh
- Faculty of Health, University of Canberra, Canberra, Australia; Justice and Society, University of South Australia, Magill SA, Australia
| | - Catherine Paterson
- Faculty of Health, University of Canberra, Canberra, Australia; Prehabilitation, Activity, Cancer, Exercise, Survivorship (PACES) Research Group, University of Canberra, Canberra, Australia
| | - Andrew J McKune
- Faculty of Health, University of Canberra, Canberra, Australia; Prehabilitation, Activity, Cancer, Exercise, Survivorship (PACES) Research Group, University of Canberra, Canberra, Australia; Research Institute for Sport and Exercise (UCRISE), Faculty of Health, University of Canberra, Canberra ACT, Australia; Discipline of Biokinetics, Exercise and Leisure Sciences, School of Health Sciences, University of KwaZulu-Natal, Durban, KwaZulu-Natal, South Africa.
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Protein Supplementation Enhances the Effects of Intermittent Loading on Skeletal Muscles by Activating the mTORC1 Signaling Pathway in a Rat Model of Disuse Atrophy. Nutrients 2020; 12:nu12092729. [PMID: 32906669 PMCID: PMC7551819 DOI: 10.3390/nu12092729] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/26/2020] [Accepted: 09/04/2020] [Indexed: 01/07/2023] Open
Abstract
Inactivity leads to skeletal muscle atrophy, whereas intermittent loading (IL) during hind limb unloading (HU) attenuates muscle atrophy. However, the combined effects of IL and protein supplementation on disuse muscle atrophy are unclear. Therefore, we investigated the effects of IL and a high-protein oral nutritional supplement (HP) during HU on skeletal muscle mass and protein synthesis/breakdown. Male F344 rats were assigned to the control (CON), 14-day HU (HU), IL during HU (HU + IL), and IL during HU followed by HP administration (2.6 g protein/kg/day; HU + IL + HP) groups. Soleus and gastrocnemius muscles were sampled 30 min after the last IL and HP supplementation. HU decreased relative soleus and gastrocnemius muscle masses. Relative muscle masses and p70 ribosomal protein S6 kinase/ribosomal protein S6 phosphorylation in soleus and gastrocnemius muscles were higher in the HU + IL group than the HU group and further higher in the HU + IL + HP group than the HU + IL group in gastrocnemius muscle. Therefore, protein administration plus IL effectively prevented skeletal muscle atrophy induced by disuse, potentially via enhanced activation of targets downstream of mammalian target of rapamycin complex 1 (mTORC1) signaling pathway.
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Hannaian SJ, Hodson N, Abou Sawan S, Mazzulla M, Kato H, Matsunaga K, Waskiw-Ford M, Duncan J, Kumbhare DA, Moore DR. Leucine-enriched amino acids maintain peripheral mTOR-Rheb localization independent of myofibrillar protein synthesis and mTORC1 signaling postexercise. J Appl Physiol (1985) 2020; 129:133-143. [PMID: 32525432 DOI: 10.1152/japplphysiol.00241.2020] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Postexercise protein ingestion can elevate rates of myofibrillar protein synthesis (MyoPS), mTORC1 activity, and mTOR translocation/protein-protein interactions. However, it is unclear if leucine-enriched essential amino acids (LEAA) can similarly facilitate intracellular mTOR trafficking in humans after exercise. The purpose of this study was to determine the effect of postexercise LEAA (4 g total EAAs, 1.6 g leucine) on acute MyoPS and mTORC1 translocation and signaling. Recreationally active men performed lower-body resistance exercise (5 × 8-10 leg press and leg extension) to volitional failure. Following exercise participants consumed LEAA (n = 8) or an isocaloric carbohydrate drink (PLA; n = 10). MyoPS was measured over 1.5-4 h of recovery by oral pulse of l-[ring-2H5]-phenylalanine. Phosphorylation of proteins in the mTORC1 pathway were analyzed via immunoblotting and mTORC1-LAMP2/WGA/Rheb colocalization via immunofluorescence microscopy. There was no difference in MyoPS between groups (LEAA = 0.098 ± 0.01%/h; PL = 0.090 ± 0.01%/h; P > 0.05). Exercise increased (P < 0.05) rpS6Ser240/244(LEAA = 35.3-fold; PLA = 20.6-fold), mTORSer2448(LEAA = 1.8-fold; PLA = 1.2-fold) and 4EBP1Thr37/46(LEAA = 1.5-fold; PLA = 1.4-fold) phosphorylation irrespective of nutrition (P > 0.05). LAT1 and SNAT2 protein expression were not affected by exercise or nutrient ingestion. mTOR-LAMP2 colocalization was greater in LEAA preexercise and decreased following exercise and supplement ingestion (P < 0.05), yet was unchanged in PLA. mTOR-WGA (cell periphery marker) and mTOR-Rheb colocalization was greater in LEAA compared with PLA irrespective of time-point (P < 0.05). In conclusion, the postexercise consumption of 4 g of LEAA maintains mTOR in peripheral regions of muscle fibers, in closer proximity to its direct activator Rheb, during prolonged recovery independent of differences in MyoPS or mTORC1 signaling compared with PLA ingestion. This intracellular localization of mTOR may serve to "prime" the kinase for future anabolic stimuli.NEW & NOTEWORTHY This is the first study to investigate whether postexercise leucine-enriched amino acid (LEAA) ingestion elevates mTORC1 translocation and protein-protein interactions in human skeletal muscle. Here, we observed that although LEAA ingestion did not further elevate postexercise MyoPS or mTORC1 signaling compared with placebo, mTORC1 peripheral location and interaction with Rheb were maintained. This may serve to "prime" mTORC1 for subsequent anabolic stimuli.
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Affiliation(s)
- Sarkis J Hannaian
- Faculty of Kinesiology and Physical Education, Department of Exercise Science, University of Toronto, Toronto, Canada
| | - Nathan Hodson
- Faculty of Kinesiology and Physical Education, Department of Exercise Science, University of Toronto, Toronto, Canada
| | - Sidney Abou Sawan
- Faculty of Kinesiology and Physical Education, Department of Exercise Science, University of Toronto, Toronto, Canada
| | - Michael Mazzulla
- Faculty of Kinesiology and Physical Education, Department of Exercise Science, University of Toronto, Toronto, Canada
| | - Hiroyuki Kato
- Technology Development Center, Institute of Food Sciences and Technologies, Ajinomoto Co., Inc., Kawasaki, Kanagawa, Japan
| | - Keiko Matsunaga
- Technology Development Center, Institute of Food Sciences and Technologies, Ajinomoto Co., Inc., Kawasaki, Kanagawa, Japan
| | - Marcus Waskiw-Ford
- Faculty of Kinesiology and Physical Education, Department of Exercise Science, University of Toronto, Toronto, Canada
| | - Justin Duncan
- Faculty of Kinesiology and Physical Education, Department of Exercise Science, University of Toronto, Toronto, Canada
| | | | - Daniel R Moore
- Faculty of Kinesiology and Physical Education, Department of Exercise Science, University of Toronto, Toronto, Canada
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17
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Marshall RN, Smeuninx B, Morgan PT, Breen L. Nutritional Strategies to Offset Disuse-Induced Skeletal Muscle Atrophy and Anabolic Resistance in Older Adults: From Whole-Foods to Isolated Ingredients. Nutrients 2020; 12:nu12051533. [PMID: 32466126 PMCID: PMC7284346 DOI: 10.3390/nu12051533] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Revised: 05/19/2020] [Accepted: 05/22/2020] [Indexed: 12/14/2022] Open
Abstract
Preserving skeletal muscle mass and functional capacity is essential for healthy ageing. Transient periods of disuse and/or inactivity in combination with sub-optimal dietary intake have been shown to accelerate the age-related loss of muscle mass and strength, predisposing to disability and metabolic disease. Mechanisms underlying disuse and/or inactivity-related muscle deterioration in the older adults, whilst multifaceted, ultimately manifest in an imbalance between rates of muscle protein synthesis and breakdown, resulting in net muscle loss. To date, the most potent intervention to mitigate disuse-induced muscle deterioration is mechanical loading in the form of resistance exercise. However, the feasibility of older individuals performing resistance exercise during disuse and inactivity has been questioned, particularly as illness and injury may affect adherence and safety, as well as accessibility to appropriate equipment and physical therapists. Therefore, optimising nutritional intake during disuse events, through the introduction of protein-rich whole-foods, isolated proteins and nutrient compounds with purported pro-anabolic and anti-catabolic properties could offset impairments in muscle protein turnover and, ultimately, the degree of muscle atrophy and recovery upon re-ambulation. The current review therefore aims to provide an overview of nutritional countermeasures to disuse atrophy and anabolic resistance in older individuals.
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Affiliation(s)
- Ryan N. Marshall
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (R.N.M.); (B.S.); (P.T.M.)
- Medical Research Council-Versus Arthritis Centre for Musculoskeletal Ageing, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Benoit Smeuninx
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (R.N.M.); (B.S.); (P.T.M.)
- Medical Research Council-Versus Arthritis Centre for Musculoskeletal Ageing, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Paul T. Morgan
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (R.N.M.); (B.S.); (P.T.M.)
- Medical Research Council-Versus Arthritis Centre for Musculoskeletal Ageing, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Leigh Breen
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK; (R.N.M.); (B.S.); (P.T.M.)
- Medical Research Council-Versus Arthritis Centre for Musculoskeletal Ageing, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
- Correspondence: ; Tel.: +44-121-414-4109
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18
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Horwath O, Apró W, Moberg M, Godhe M, Helge T, Ekblom M, Hirschberg AL, Ekblom B. Fiber type-specific hypertrophy and increased capillarization in skeletal muscle following testosterone administration in young women. J Appl Physiol (1985) 2020; 128:1240-1250. [PMID: 32191598 DOI: 10.1152/japplphysiol.00893.2019] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
It is well established that testosterone administration induces muscle fiber hypertrophy and myonuclear addition in men; however, it remains to be determined whether similar morphological adaptations can be achieved in women. The aim of the present study was therefore to investigate whether exogenously administered testosterone alters muscle fiber morphology in skeletal muscle of young healthy, physically active women. Thirty-five young (20-35 yr), recreationally trained women were randomly assigned to either 10-wk testosterone administration (10 mg daily) or placebo. Before and after the intervention, hormone concentrations and body composition were assessed, and muscle biopsies were obtained from the vastus lateralis. Fiber type composition, fiber size, satellite cell and myonuclei content, as well as muscle capillarization were assessed in a fiber type-specific manner by immunohistochemistry. After the intervention, testosterone administration elevated serum testosterone concentration (5.1-fold increase, P = 0.001) and induced significant accretion of total lean mass (+1.9%, P = 0.002) and leg lean mass (+2.4%, P = 0.001). On the muscle fiber level, testosterone increased mixed-fiber cross-sectional area (+8.2%, P = 0.001), an effect primarily driven by increases in type II fiber size (9.2%, P = 0.006). Whereas myonuclei content remained unchanged, a numerical increase (+30.8%) was found for satellite cells associated with type II fibers in the Testosterone group. In parallel with fiber hypertrophy, testosterone significantly increased capillary contacts (+7.5%, P = 0.015) and capillary-to-fiber ratio (+9.2%, P = 0.001) in type II muscle fibers. The present study provides novel insight into fiber type-specific adaptations present already after 10 wk of only moderately elevated testosterone levels in women.NEW & NOTEWORTHY We have recently demonstrated performance-enhancing effects of moderately elevated testosterone concentrations in young women. Here we present novel evidence that testosterone alters muscle morphology in these women, resulting in type II fiber hypertrophy and improved capillarization. Our findings suggest that low doses of testosterone potently impact skeletal muscle after only 10 wk. These data provide unique insights into muscle adaptation and support the performance-enhancing role of testosterone in women on the muscle fiber level.
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Affiliation(s)
- Oscar Horwath
- Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - William Apró
- Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Marcus Moberg
- Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Manne Godhe
- Department of Sport Performance and Training, Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Torbjörn Helge
- Department of Sport Performance and Training, Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Maria Ekblom
- Biomechanics and Motor Control Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Angelica Lindén Hirschberg
- Division of Obstetrics and Gynaecology, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.,Department of Gynaecology and Reproductive Medicine, Karolinska University Hospital, Stockholm, Sweden
| | - Björn Ekblom
- Åstrand Laboratory, Swedish School of Sport and Health Sciences, Stockholm, Sweden
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19
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Wyckelsma VL, Lindkvist W, Venckunas T, Brazaitis M, Kamandulis S, Pääsuke M, Ereline J, Westerblad H, Andersson DC. Kynurenine aminotransferase isoforms display fiber-type specific expression in young and old human skeletal muscle. Exp Gerontol 2020; 134:110880. [PMID: 32068089 DOI: 10.1016/j.exger.2020.110880] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 02/12/2020] [Accepted: 02/12/2020] [Indexed: 12/27/2022]
Abstract
Conversion of kynurenine (KYN) to kynurenic acid (KYNA) is the main pathway for free tryptophan degradation in skeletal muscle and has emerged as an important mechanism of how exercise is linked to promotion of mental health. Metabolism of KYN to KYNA mainly depends on the expression of kynurenine aminotransferases (KATs) that is under control of the mitochondria biogenesis regulator PGC-1α. We therefore hypothesized that expression of KATs would vary between muscle fibers that differ in mitochondrial content, i.e. oxidative type I vs more glycolytic type II muscle fibers. Moreover, we tested the hypothesis that KAT expression differs with age. Single muscle fibers were isolated from biopsies taken from the vastus lateralis muscle in young and old healthy subjects. In young and old subjects the abundance of KAT I, KAT III and KAT IV was greater in Type I than Type II fibers without age-dependent difference in the KAT isoform expressions. The link to mitochondrial content was further seen as the expression of KAT IV correlated to mitochondrial cytochrome c oxidase IV (COX IV) abundance in both fiber types. In conclusion, we describe for the first time the expression pattern of KAT isoforms with respect to specific fiber types and age in human skeletal muscle.
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Affiliation(s)
- V L Wyckelsma
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - W Lindkvist
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - T Venckunas
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - M Brazaitis
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - S Kamandulis
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - M Pääsuke
- Institute of Sport Sciences and Physiotherapy, Faculty of Medicine, University of Tartu, Estonia
| | - J Ereline
- Institute of Sport Sciences and Physiotherapy, Faculty of Medicine, University of Tartu, Estonia
| | - H Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - D C Andersson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden; Heart, Vascular and Neurology Theme, Section for Cardiology, Karolinska University Hospital, Stockholm, Sweden.
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20
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Hodson N, West DWD, Philp A, Burd NA, Moore DR. Molecular regulation of human skeletal muscle protein synthesis in response to exercise and nutrients: a compass for overcoming age-related anabolic resistance. Am J Physiol Cell Physiol 2019; 317:C1061-C1078. [PMID: 31461340 DOI: 10.1152/ajpcell.00209.2019] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Skeletal muscle mass, a strong predictor of longevity and health in humans, is determined by the balance of two cellular processes, muscle protein synthesis (MPS) and muscle protein breakdown. MPS seems to be particularly sensitive to changes in mechanical load and/or nutritional status; therefore, much research has focused on understanding the molecular mechanisms that underpin this cellular process. Furthermore, older individuals display an attenuated MPS response to anabolic stimuli, termed anabolic resistance, which has a negative impact on muscle mass and function, as well as quality of life. Therefore, an understanding of which, if any, molecular mechanisms contribute to anabolic resistance of MPS is of vital importance in formulation of therapeutic interventions for such populations. This review summarizes the current knowledge of the mechanisms that underpin MPS, which are broadly divided into mechanistic target of rapamycin complex 1 (mTORC1)-dependent, mTORC1-independent, and ribosomal biogenesis-related, and describes the evidence that shows how they are regulated by anabolic stimuli (exercise and/or nutrition) in healthy human skeletal muscle. This review also summarizes evidence regarding which of these mechanisms may be implicated in age-related skeletal muscle anabolic resistance and provides recommendations for future avenues of research that can expand our knowledge of this area.
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Affiliation(s)
- Nathan Hodson
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Daniel W D West
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
| | - Andrew Philp
- Garvan Institute of Medical Research, Darlinghurst, Sydney, New South Wales, Australia
| | - Nicholas A Burd
- Department of Kinesiology and Community Health, University of Illinois, Urbana, Illinois
| | - Daniel R Moore
- Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada
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