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Scalzo RL, Schauer IE, Rafferty D, Knaub LA, Kvaratskhelia N, Johnson TK, Pott GB, Abushamat LA, Whipple MO, Huebschmann AG, Cree-Green M, Reusch JEB, Regensteiner JG. Single-leg exercise training augments in vivo skeletal muscle oxidative flux and vascular content and function in adults with type 2 diabetes. J Physiol 2022; 600:963-978. [PMID: 33569797 PMCID: PMC9006339 DOI: 10.1113/jp280603] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 01/28/2021] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS People with type 2 diabetes (T2D) have impaired skeletal muscle oxidative flux due to limited oxygen delivery. In the current study, this impairment in oxidative flux in people with T2D was abrogated with a single-leg exercise training protocol. Additionally, single-leg exercise training increased skeletal muscle CD31 content, calf blood flow and state 4 mitochondrial respiration in all participants. ABSTRACT Cardiorespiratory fitness is impaired in type 2 diabetes (T2D), conferring significant cardiovascular risk in this population; interventions are needed. Previously, we reported that a T2D-associated decrement in skeletal muscle oxidative flux is ameliorated with acute use of supplemental oxygen, suggesting that skeletal muscle oxygenation is rate-limiting to in vivo mitochondrial oxidative flux during exercise in T2D. We hypothesized that single-leg exercise training (SLET) would improve the T2D-specific impairment in in vivo mitochondrial oxidative flux during exercise. Adults with (n = 19) and without T2D (n = 22) with similar body mass indexes and levels of physical activity participated in two weeks of SLET. Following SLET, in vivo oxidative flux measured by 31 P-MRS increased in participants with T2D, but not people without T2D, measured by the increase in initial phosphocreatine synthesis (P = 0.0455 for the group × exercise interaction) and maximum rate of oxidative ATP synthesis (P = 0.0286 for the interaction). Additionally, oxidative phosphorylation increased in all participants with SLET (P = 0.0209). After SLET, there was no effect of supplemental oxygen on any of the in vivo oxidative flux measurements in either group (P > 0.02), consistent with resolution of the T2D-associated oxygen limitation previously observed at baseline in subjects with T2D. State 4 mitochondrial respiration also improved in muscle fibres ex vivo. Skeletal muscle vasculature content and calf blood flow increased in all participants with SLET (P < 0.0040); oxygen extraction in the calf increased only in T2D (P = 0.0461). SLET resolves the T2D-associated impairment of skeletal muscle in vivo mitochondrial oxidative flux potentially through improved effective blood flow/oxygen delivery.
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Affiliation(s)
- Rebecca L Scalzo
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Irene E Schauer
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Deirdre Rafferty
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Leslie A Knaub
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Nina Kvaratskhelia
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Taro Kaelix Johnson
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Gregory B Pott
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Layla A Abushamat
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Mary O Whipple
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Amy G Huebschmann
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Melanie Cree-Green
- Division of Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of Pediatric Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Jane E B Reusch
- Division of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Rocky Mountain Regional Veterans Administration Medical Center, Aurora, Colorado, USA
| | - Judith G Regensteiner
- Division of General Internal Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
- Division of Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado, USA
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Scalzo RL, Rafferty D, Schauer I, Huebschmann AG, Cree-Green M, Reusch JEB, Regensteiner JG. Sitagliptin improves diastolic cardiac function but not cardiorespiratory fitness in adults with type 2 diabetes. J Diabetes Complications 2019; 33:561-566. [PMID: 31182338 PMCID: PMC7278036 DOI: 10.1016/j.jdiacomp.2019.05.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 04/17/2019] [Accepted: 05/05/2019] [Indexed: 01/04/2023]
Abstract
BACKGROUND People with type 2 diabetes mellitus (T2D) have preclinical cardiac and vascular dysfunction associated with low cardiorespiratory fitness (CRF). This is especially concerning because CRF is a powerful predictor of cardiovascular mortality, a primary issue in T2D management. Glucagon-like pepetide-1 (GLP-1) augments cardiovascular function and our previous data in rodents demonstrate that potentiating the GLP-1 signal with a dipeptidyl peptidase-4 (DPP4) inhibitor augments CRF. Lacking are pharmacological treatments which can target T2D-specific physiological barriers to exercise to potentially permit adaptations necessary to improve CRF and thereby health outcomes in people with T2D. We therefore hypothesized that administration of a DPP4-inhibitor (sitagliptin) would improve CRF in adults with T2D. METHODS AND RESULTS Thirty-eight participants (64 ± 1 years; mean ± SE) with T2D were randomized in a double-blinded study to receive 100 mg/day sitagliptin, 2 mg/day glimepiride, or placebo for 3 months after baseline measurements. Fasting glucose decreased with both glimepiride and sitagliptin compared with placebo (P = 0.002). CRF did not change in any group (Placebo: Pre: 15.4 ± 0.9 vs. Post: 16.1 ± 1.1 ml/kg/min vs. Glimepiride: 18.5 ± 1.0 vs. 17.7 ± 1.2 ml/kg/min vs. Sitagliptin: 19.1 ± 1.2 vs. 18.3 ± 1.1 ml/kg/min; P = 0.3). Sitagliptin improved measures of cardiac diastolic function, however, measures of vascular function did not change with any treatment. CONCLUSIONS Three months of sitagliptin improved diastolic cardiac function, however, CRF did not change. These data suggest that targeting the physiological contributors to CRF with sitagliptin alone is not an adequate strategy to improve CRF in people with T2D. CLINICAL TRIALS REGISTRATION www.clinicaltrials.gov NCT01951339.
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Affiliation(s)
- Rebecca L Scalzo
- Division of Endocrinology, Department of Medicine, University of Colorado School of Medicine, United States of America; Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, United States of America; Rocky Mountain Regional Veterans Administration Medical Center, United States of America.
| | - Deirdre Rafferty
- Division of General Internal Medicine, Department of Medicine, University of Colorado School of Medicine, United States of America
| | - Irene Schauer
- Division of Endocrinology, Department of Medicine, University of Colorado School of Medicine, United States of America; Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, United States of America; Rocky Mountain Regional Veterans Administration Medical Center, United States of America
| | - Amy G Huebschmann
- Division of General Internal Medicine, Department of Medicine, University of Colorado School of Medicine, United States of America; Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, United States of America
| | - Melanie Cree-Green
- Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, United States of America; Division of Pediatric Endocrinology, University of Colorado School of Medicine, United States of America
| | - Jane E B Reusch
- Division of Endocrinology, Department of Medicine, University of Colorado School of Medicine, United States of America; Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, United States of America; Rocky Mountain Regional Veterans Administration Medical Center, United States of America
| | - Judith G Regensteiner
- Division of General Internal Medicine, Department of Medicine, University of Colorado School of Medicine, United States of America; Center for Women's Health Research, Department of Medicine, University of Colorado School of Medicine, United States of America
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Cree-Green M, Scalzo RL, Harrall K, Newcomer BR, Schauer IE, Huebschmann AG, McMillin S, Brown MS, Orlicky D, Knaub L, Nadeau KJ, McClatchey PM, Bauer TA, Regensteiner JG, Reusch JEB. Supplemental Oxygen Improves In Vivo Mitochondrial Oxidative Phosphorylation Flux in Sedentary Obese Adults With Type 2 Diabetes. Diabetes 2018; 67:1369-1379. [PMID: 29643061 PMCID: PMC6463751 DOI: 10.2337/db17-1124] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 03/29/2018] [Indexed: 12/11/2022]
Abstract
Type 2 diabetes is associated with impaired exercise capacity. Alterations in both muscle perfusion and mitochondrial function can contribute to exercise impairment. We hypothesized that impaired muscle mitochondrial function in type 2 diabetes is mediated, in part, by decreased tissue oxygen delivery and would improve with oxygen supplementation. Ex vivo muscle mitochondrial content and respiration assessed from biopsy samples demonstrated expected differences in obese individuals with (n = 18) and without (n = 17) diabetes. Similarly, in vivo mitochondrial oxidative phosphorylation capacity measured in the gastrocnemius muscle via 31P-MRS indicated an impairment in the rate of ADP depletion with rest (27 ± 6 s [diabetes], 21 ± 7 s [control subjects]; P = 0.008) and oxidative phosphorylation (P = 0.046) in type 2 diabetes after isometric calf exercise compared with control subjects. Importantly, the in vivo impairment in oxidative capacity resolved with oxygen supplementation in adults with diabetes (ADP depletion rate 5.0 s faster, P = 0.012; oxidative phosphorylation 0.046 ± 0.079 mmol/L/s faster, P = 0.027). Multiple in vivo mitochondrial measures related to HbA1c These data suggest that oxygen availability is rate limiting for in vivo mitochondrial oxidative exercise recovery measured with 31P-MRS in individuals with uncomplicated diabetes. Targeting muscle oxygenation could improve exercise function in type 2 diabetes.
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Affiliation(s)
- Melanie Cree-Green
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of Pediatric Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Rebecca L Scalzo
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of Endocrinology and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Kylie Harrall
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- School of Pharmacy, University of Colorado Anschutz Medical Campus, Aurora, CO
| | | | - Irene E Schauer
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of Endocrinology and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
- Veterans Affairs Medical Center, Denver, CO
| | - Amy G Huebschmann
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Shawna McMillin
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Mark S Brown
- Department of Radiology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - David Orlicky
- Division of Pathology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Leslie Knaub
- Division of Endocrinology and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Kristen J Nadeau
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of Pediatric Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - P Mason McClatchey
- Division of Endocrinology and Metabolism, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Timothy A Bauer
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Judith G Regensteiner
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
- Division of Cardiology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Jane E B Reusch
- Center for Women's Health Research, Anschutz Medical Campus, Aurora, CO
- Veterans Affairs Medical Center, Denver, CO
- Division of General Internal Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO
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Cree-Green M, Cai N, Pyle L, Ringham B, Brown MS, Newcomer BR, Nadeau KJ, Dabelea D. Insulin Resistance in Youth Without Diabetes Is Not Related to Muscle Mitochondrial Dysfunction. J Clin Endocrinol Metab 2017; 102:1652-1660. [PMID: 28204552 PMCID: PMC5443327 DOI: 10.1210/jc.2016-3912] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 02/03/2017] [Indexed: 12/19/2022]
Abstract
Context Obesity, insulin resistance (IR), and diabetes are increasing in youth, especially in girls. IR is associated with muscle mitochondrial dysfunction in youth and adults with diabetes. However, it is unknown whether this relationship is present in youth prior to development of diabetes. Objective Assess IR and mitochondrial function, including sex differences, in nondiabetic youth. Design Cross-sectional study of youth in the Exploring Perinatal Outcomes among Children, Resistance to InSulin in Type 1 And Type 2 diabetes, and Androgens and Insulin Resistance Study cohorts. Setting Academic medical university. Participants Two hundred seventy-five youth, 13 to 19 years old [43% males: 17.1 (16.52, 17.63) years, body mass index z-score (BMI-Z) 0.36, 64.7% Tanner 5; 57% females: 17.2 (16.43, 17.67) years, BMI-Z 0.72, 78.9% Tanner 5]. Interventions Fasting laboratories, oral glucose tolerance test, and 31P magnetic resonance spectroscopy. Main Outcome Measures IR [triglyceride:high-density lipoprotein (HDL) ratio, Matsuda index, and homeostasis model for insulin resistance (HOMA-IR)] and muscle mitochondrial function (adenosine 5'-diphosphate time constant and oxidative phosphorylation rate). Results Compared with males, females were more insulin resistant, with higher triglyceride:HDL ratio [1.95 (1.30, 2.79) vs 1.69 (1.21, 2.23), P = 0.042], HOMA-IR [3.18 (2.42, 4.39) vs 2.76 (2.02, 4.08), P = 0.035], and fasting free fatty acids (FFAs) and lower Matsuda score [3.98 (2.71, 5.96) vs 5.39 (3.43, 7.57), P < 0.001]. After adjustment for the higher BMI and Tanner stage and lower physical activity levels seen in females, there were no sex differences in mitochondrial function nor in any IR measure except FFAs. We did not find an association between measures of IR and mitochondrial function. Conclusions The greater IR seen in adolescent girls vs boys is mostly explained by differences in BMI and physical activity. Mitochondrial function does not appear to be related to IR in a large cohort of nondiabetic youth.
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Affiliation(s)
- Melanie Cree-Green
- Pediatric Endocrinology, University of Colorado Anschutz and Children’s Hospital Colorado, Aurora, Colorado 80045
| | - Ninghe Cai
- Pediatric Endocrinology, University of Colorado Anschutz and Children’s Hospital Colorado, Aurora, Colorado 80045
| | - Laura Pyle
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado 80045
- Department of Biostatistics and Informatics, Colorado School of Public Health, Aurora, Colorado 80045
| | - Brandy Ringham
- Department of Epidemiology, Colorado School of Public Health, Aurora, Colorado 80045
| | - Mark S. Brown
- Radiology, University of Colorado School of Medicine, Anschutz Medical Campus, Aurora, Colorado 80045
| | - Bradley R. Newcomer
- Department of Physics, James Madison University, Harrisonburg, Virginia 22807
| | - Kristen J. Nadeau
- Pediatric Endocrinology, University of Colorado Anschutz and Children’s Hospital Colorado, Aurora, Colorado 80045
| | - Dana Dabelea
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado 80045
- Department of Epidemiology, Colorado School of Public Health, Aurora, Colorado 80045
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Barclay CJ. Energy demand and supply in human skeletal muscle. J Muscle Res Cell Motil 2017; 38:143-155. [PMID: 28286928 DOI: 10.1007/s10974-017-9467-7] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 02/14/2017] [Indexed: 12/18/2022]
Abstract
The energy required for muscle contraction is provided by the breakdown of ATP but the amount of ATP in muscles cells is sufficient to power only a short duration of contraction. Buffering of ATP by phosphocreatine, a reaction catalysed by creatine kinase, extends the duration of activity possible but sustained activity depends on continual regeneration of PCr. This is achieved using ATP generated by oxidative processes and, during intense activity, by anaerobic glycolysis. The rate of ATP breakdown ranges from 70 to 140 mM min-1 during isometric contractions of various intensity to as much as 400 mM min-1 during intense, dynamic activity. The maximum rate of oxidative energy supply in untrained people is ~50 mM min-1 which, if the contraction duty cycle is 0.5 as is often the case in cyclic activity, is sufficient to match an ATP breakdown rate during contraction of 100 mM min-1. During brief, intense activity the rate of ATP turnover can exceed the rates of PCr regeneration by combined oxidative and glycolytic energy supply, resulting in a net decrease in PCr concentration. Glycolysis has the capacity to produce between 30 and 50 mM of ATP so that, for example, anaerobic glycolysis could provide ATP at an average of 100 mM min-1 over 30 s of exhausting activity. The creatine kinase reaction plays an important role not only in buffering ATP but also in communicating energy demand from sites of ATP breakdown to the mitochondria. In that role, creatine kinases acts to slow and attenuate the response of mitochondria to changes in energy demand.
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Affiliation(s)
- C J Barclay
- School of Allied Health Sciences, Griffith University, Gold Coast, QLD, 4222, Australia.
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Cree-Green M, Gupta A, Coe GV, Baumgartner AD, Pyle L, Reusch JEB, Brown MS, Newcomer BR, Nadeau KJ. Insulin resistance in type 2 diabetes youth relates to serum free fatty acids and muscle mitochondrial dysfunction. J Diabetes Complications 2017; 31:141-148. [PMID: 27839922 PMCID: PMC5395421 DOI: 10.1016/j.jdiacomp.2016.10.014] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 09/14/2016] [Accepted: 10/10/2016] [Indexed: 12/15/2022]
Abstract
AIMS Insulin resistance (IR) correlates with mitochondrial dysfunction, free fatty acids (FFAs), and intramyocellular lipid (IMCL) in adults with type 2 diabetes (T2D). We hypothesized that muscle IR would relate to similar factors in T2D youth. METHODS Participants included 17 youth with T2D, 23 normal weight controls (LCs), and 26 obese controls (OBs) of similar pubertal stage and activity level. RESULTS T2D and OB groups were of similar BMI. T2D youth were significantly more IR and had higher calf IMCL and serum FFA concentrations during hyperinsulinemia. ADP time constant (ADPTC), a blood-flow dependent mitochondrial function measure, was slowed and oxidative phosphorylation rates lower in T2D. In multiple linear regression of the entire cohort, lack of FFA suppression and longer ADPTC, but not IMCL or HbA1c, were independently associated with IR. CONCLUSION We found that elevated FFAs and mitochondrial dysfunction are early abnormalities in relatively well-controlled youth with T2D. Further, post-exercise oxidative metabolism appears affected by reduced blood flow, and is not solely an inherent mitochondrial defect. Thus, lowering FFAs and improving mitochondrial function and blood flow may be potential treatment targets in youth with T2D.
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Affiliation(s)
- Melanie Cree-Green
- Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus and Children's Hospital Colorado, Aurora, CO, 80045; Center for Women's Health Research, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045.
| | - Abhinav Gupta
- Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus and Children's Hospital Colorado, Aurora, CO, 80045
| | - Gregory V Coe
- Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus and Children's Hospital Colorado, Aurora, CO, 80045
| | - Amy D Baumgartner
- Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus and Children's Hospital Colorado, Aurora, CO, 80045
| | - Laura Pyle
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045; Department of Biostatistics and Informatics, Colorado School of Public Health, Aurora, CO, 80045
| | - Jane E B Reusch
- Center for Women's Health Research, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045; Division of Endocrinology, Metabolism and Diabetes, University to Colorado Anschutz Medical Campus, Aurora, CO, 80045; Veterans Affairs Medical Center, Aurora, CO, 80012
| | - Mark S Brown
- Department of Radiology, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045
| | | | - Kristen J Nadeau
- Division of Pediatric Endocrinology, University of Colorado Anschutz Medical Campus and Children's Hospital Colorado, Aurora, CO, 80045; Center for Women's Health Research, University of Colorado Anschutz Medical Campus, Aurora, CO, 80045
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Freitas FFMD, Azevedo DPD, Medeiros WM, Neder JA, Chiavegato LD, Amorim CF. Microvascular oxygen extraction during maximal isometric contraction in patients with chronic obstructive pulmonary disease. FISIOTERAPIA EM MOVIMENTO 2016. [DOI: 10.1590/1980-5918.029.004.ao16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Abstract Introduction: COPD presents decrease in oxidative metabolism with possible losses of cardiovascular adjustments, suggesting slow kinetics microvascular oxygen during intense exercise. Objective: To test the hypothesis that chronic obstructive pulmonary disease (COPD) patients have lower muscle performance in physical exercise not dependent on central factors, but also greater muscle oxygen extraction, regardless of muscle mass. Methods: Cross-sectional study with 11 COPD patients and nine healthy subjects, male, paired for age. Spirometry and body composition by DEXA were evaluated. Muscular performance was assessed by maximal voluntary isometric contraction (MVIC) in isokinetic dynamometer and muscle oxygen extraction by the NIRS technique. Student t-test and Pearson correlation were applied. A significance level of p<0.05 was adopted. Results: Patients had moderate to severe COPD (FEV1 = 44.5 ± 9.6% predicted; SpO2 = 94.6 ± 1.6%). Lean leg mass was 8.3 ± 0.9 vs. 8.9 ± 1.0 kg (p =0.033), when comparing COPD and control patients, respectively. The decreased muscle oxygen saturation corrected by muscle mass was 53.2% higher (p=0.044) in the COPD group in MVIC-1 and 149.6% higher (p=0.006) in the MVIC-2. Microvascular extraction rate of oxygen corrected by muscle mass and total work was found to be 114.5% higher (p=0.043) in the COPD group in MVIC-1 and 210.5% higher (p=0.015) in the MVIC-2. Conclusion: COPD patients have low muscle performance and high oxygen extraction per muscle mass unit and per unit of work. The high oxygen extraction suggests that quantitative and qualitative mechanisms can be determinants of muscle performance in patients with COPD.
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Callahan DM, Umberger BR, Kent JA. Mechanisms of in vivo muscle fatigue in humans: investigating age-related fatigue resistance with a computational model. J Physiol 2016; 594:3407-21. [PMID: 26824934 DOI: 10.1113/jp271400] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 01/20/2016] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Muscle fatigue can be defined as the transient decrease in maximal force that occurs in response to muscle use. Fatigue develops because of a complex set of changes within the neuromuscular system that are difficult to evaluate simultaneously in humans. The skeletal muscle of older adults fatigues less than that of young adults during static contractions. The potential sources of this difference are multiple and intertwined. To evaluate the individual mechanisms of fatigue, we developed an integrative computational model based on neural, biochemical, morphological and physiological properties of human skeletal muscle. Our results indicate first that the model provides accurate predictions of fatigue and second that the age-related resistance to fatigue is due largely to a lower reliance on glycolytic metabolism during contraction. This model should prove useful for generating hypotheses for future experimental studies into the mechanisms of muscle fatigue. ABSTRACT During repeated or sustained muscle activation, force-generating capacity becomes limited in a process referred to as fatigue. Multiple factors, including motor unit activation patterns, muscle fibre contractile properties and bioenergetic function, can impact force-generating capacity and thus the potential to resist fatigue. Given that neuromuscular fatigue depends on interrelated factors, quantifying their independent effects on force-generating capacity is not possible in vivo. Computational models can provide insight into complex systems in which multiple inputs determine discrete outputs. However, few computational models to date have investigated neuromuscular fatigue by incorporating the multiple levels of neuromuscular function known to impact human in vivo function. To address this limitation, we present a computational model that predicts neural activation, biomechanical forces, intracellular metabolic perturbations and, ultimately, fatigue during repeated isometric contractions. This model was compared with metabolic and contractile responses to repeated activation using values reported in the literature. Once validated in this way, the model was modified to reflect age-related changes in neuromuscular function. Comparisons between initial and age-modified simulations indicated that the age-modified model predicted less fatigue during repeated isometric contractions, consistent with reports in the literature. Together, our simulations suggest that reduced glycolytic flux is the greatest contributor to the phenomenon of age-related fatigue resistance. In contrast, oxidative resynthesis of phosphocreatine between intermittent contractions and inherent buffering capacity had minimal impact on predicted fatigue during isometric contractions. The insights gained from these simulations cannot be achieved through traditional in vivo or in vitro experimentation alone.
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Affiliation(s)
- Damien M Callahan
- Department of Kinesiology, University of Massachusetts, Amherst, MA, USA
| | - Brian R Umberger
- Department of Kinesiology, University of Massachusetts, Amherst, MA, USA
| | - Jane A Kent
- Department of Kinesiology, University of Massachusetts, Amherst, MA, USA
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Cree-Green M, Newcomer BR, Coe G, Newnes L, Baumgartner A, Brown MS, Pyle L, Reusch JE, Nadeau KJ. Peripheral insulin resistance in obese girls with hyperandrogenism is related to oxidative phosphorylation and elevated serum free fatty acids. Am J Physiol Endocrinol Metab 2015; 308:E726-33. [PMID: 25714677 PMCID: PMC4420897 DOI: 10.1152/ajpendo.00619.2014] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 02/19/2015] [Indexed: 12/25/2022]
Abstract
Hyperandrogenic syndrome (HAS) is associated with insulin resistance (IR) and type 2 diabetes. Muscle IR in type 2 diabetes is linked with defects in mitochondrial oxidative capacity. In vivo muscle mitochondrial function has not been studied in HAS, especially in youth, who are early in the disease process. Our goal was to measure muscle mitochondrial oxidative function and peripheral IR in obese youth with HAS. Obese girls without HAS [n = 22, age 15(13,17) yr, BMI Z-score 2.05 ± 0.37] and with HAS [n = 35, age 15(14,16) yr, BMI Z-score 2.18 ± 0.30] were enrolled. Mitochondrial function was assessed with (31)phosphorus MR spectroscopy before, during, and after near-maximal isometric calf exercise, and peripheral IR was assessed with an 80 mU·m(-2)·min(-1) hyperinsulinemic euglycemic clamp. Girls with HAS had higher androgens [free androgen index 7.9(6.6,15.5) vs. 3.5(3.0,4.0), P < 0.01] and more IR [glucose infusion rate 9.4(7.0, 12,2) vs. 14.5(13.2,15.8) mg·kg lean(-1)·min(-1), P < 0.01]. HAS girls also had increased markers of inflammation including CRP, platelets, and white blood cell count and higher serum free fatty acids during hyperinsulinemia. Mitochondrial oxidative phosphorylation was lower in HAS [0.11(0.06,0.19) vs. 0.18(0.12,0.23) mmol/s, P < 0.05], although other spectroscopy markers of mitochondrial function were similar between groups. In multivariate analysis of the entire cohort, IR related to androgens, oxidative phosphorylation, and free fatty acid concentrations during hyperinsulinemia. These relationships were present in just the HAS cohort as well. Obese girls with HAS have significant peripheral IR, which is related to elevated androgens and free fatty acids and decreased mitochondrial oxidative phosphorylation. These may provide future options as targets for therapeutic intervention.
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Affiliation(s)
- Melanie Cree-Green
- Division of Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado; Center for Women's Health Research, Anschutz Medical Campus, Aurora, Colorado;
| | - Bradley R Newcomer
- Department of Clinical and Diagnostic Sciences, University of Alabama at Birmingham, Birmingham, Alabama
| | - Gregory Coe
- Division of Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Lindsey Newnes
- Division of Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Amy Baumgartner
- Division of Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Mark S Brown
- Department of Radiology, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Laura Pyle
- Department of Pediatrics, University of Colorado School of Medicine, and Department of Biostatistics and Informatics, Colorado School of Public Health, Aurora, Colorado
| | - Jane E Reusch
- Division of Endocrinology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado; and Department of Veteran Affairs, Denver, Colorado
| | - Kristen J Nadeau
- Division of Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, Colorado; Center for Women's Health Research, Anschutz Medical Campus, Aurora, Colorado
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10
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Cree-Green M, Newcomer BR, Brown MS, Baumgartner AD, Bergman B, Drew B, Regensteiner JG, Pyle L, Reusch JEB, Nadeau KJ. Delayed skeletal muscle mitochondrial ADP recovery in youth with type 1 diabetes relates to muscle insulin resistance. Diabetes 2015; 64:383-92. [PMID: 25157095 PMCID: PMC4303961 DOI: 10.2337/db14-0765] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Insulin resistance (IR) increases cardiovascular morbidity and is associated with mitochondrial dysfunction. IR is now recognized to be present in type 1 diabetes; however, its relationship with mitochondrial function is unknown. We determined the relationship between IR and muscle mitochondrial function in type 1 diabetes using the hyperinsulinemic-euglycemic clamp and (31)P-MRS before, during, and after near-maximal isometric calf exercise. Volunteers included 21 nonobese adolescents with type 1 diabetes and 17 nondiabetic control subjects with similar age, sex, BMI, Tanner stage, and activity levels. We found that youths with type 1 diabetes were more insulin resistant (median glucose infusion rate 10.1 vs. 18.9 mg/kglean/min; P < 0.0001) and had a longer time constant of the curve of ADP conversion to ATP (23.4 ± 5.3 vs. 18.8 ± 3.9 s, P < 0.001) and a lower rate of oxidative phosphorylation (median 0.09 vs. 0.21 mmol/L/s, P < 0.001). The ADP time constant (β = -0.36, P = 0.026) and oxidative phosphorylation (β = 0.02, P < 0.038) were related to IR but not HbA1c. Normal-weight youths with type 1 diabetes demonstrated slowed postexercise ATP resynthesis and were more insulin resistant than control subjects. The correlation between skeletal muscle mitochondrial dysfunction in type 1 diabetes and IR suggests a relationship between mitochondrial dysfunction and IR in type 1 diabetes.
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Affiliation(s)
- Melanie Cree-Green
- Division of Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO Center for Women's Health Research, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Bradley R Newcomer
- Department of Clinical and Diagnostic Sciences, University of Alabama at Birmingham, Birmingham, AL
| | - Mark S Brown
- Department of Radiology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Amy D Baumgartner
- Division of Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Bryan Bergman
- Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO Division of Endocrinology and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Brendan Drew
- Division of Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Judith G Regensteiner
- Center for Women's Health Research, University of Colorado Anschutz Medical Campus, Aurora, CO Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO Divisions of General Internal Medicine and Cardiology, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Laura Pyle
- Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Jane E B Reusch
- Center for Women's Health Research, University of Colorado Anschutz Medical Campus, Aurora, CO Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO Division of Endocrinology and Metabolism, University of Colorado Anschutz Medical Campus, Aurora, CO Veterans Affairs Medical Center, Denver, CO
| | - Kristen J Nadeau
- Division of Endocrinology, Department of Pediatrics, University of Colorado Anschutz Medical Campus, Aurora, CO Center for Women's Health Research, University of Colorado Anschutz Medical Campus, Aurora, CO
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11
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Abstract
Skeletal muscle fatigue is defined as the fall of force or power in response to contractile activity. Both the mechanisms of fatigue and the modes used to elicit it vary tremendously. Conceptual and technological advances allow the examination of fatigue from the level of the single molecule to the intact organism. Evaluation of muscle fatigue in a wide range of disease states builds on our understanding of basic function by revealing the sources of dysfunction in response to disease.
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Affiliation(s)
- Jane A Kent-Braun
- Department of Kinesiology, University of Massachusetts-Amherst, Amherst, Massachusetts, USA.
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Li K, Hogrel JY, Duchêne J, Hewson DJ. Analysis of fatigue and tremor during sustained maximal grip contractions using Hilbert-Huang Transformation. Med Eng Phys 2011; 34:832-40. [PMID: 22177573 DOI: 10.1016/j.medengphy.2011.09.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 09/27/2011] [Accepted: 09/28/2011] [Indexed: 10/14/2022]
Abstract
The objective of this study was to evaluate muscle fatigue and tremor during a Sustained Maximal Grip Contraction (SMGC) using the Hilbert-Huang Transformation (HHT). Thirty-nine healthy subjects volunteered for the study and performed a 25-s SMGC. Fatigue parameters such as the relative force output (RFO) were calculated from the residual of SMGC after applying Empirical Mode Decomposition (EMD). Using the energy spectrum of the Intrinsic Mode Functions (IMF) obtained using HHT, isometric force tremor was identified from the 4 to 12 Hz region in IMF3 and IMF4. Data were analysed for five consecutive 5-s epochs to identify changes in fatigue and tremor over time. The HHT method was able to identify a greater resistance to fatigue in women compared to men (p≤0.05) and in non-dominant hands compared to dominant hands (p≤0.05). Consistent with the results for fatigue, women had less tremor than men (p≤0.05), while non-dominant hands trembled less than did dominant hands (p≤0.05). Higher levels of tremor were observed for non-fatigue-resistant subjects for both 10-15 s and 15-20 s epochs (p≤0.05). The HHT is an appropriate method to identify both fatigue and tremor during SMGC. It would be of interest to apply this method to the study the elderly or patients with neuromuscular disorders.
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13
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Matsuura C, Gomes PSC, Haykowsky M, Bhambhani Y. Cerebral and muscle oxygenation changes during static and dynamic knee extensions to voluntary fatigue in healthy men and women: a near infrared spectroscopy study. Clin Physiol Funct Imaging 2010; 31:114-23. [PMID: 21029329 DOI: 10.1111/j.1475-097x.2010.00986.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The aim of the study was to examine the changes in cerebral and muscle blood volume (Cbv, Mbv) and oxygenation (Cox, Mox) during static and dynamic knee extensions to fatigue in men (N=10; 29±9 years) and women (N=14; 27±8 years). After assessment of 1 repetition maximum (1RM) during unilateral knee extensions with the dominant limb, each subject exercised at 50%, 75% and 100% of 1 RM in random order on separate occasions. Simultaneous changes in Cbv, Cox, Mbv and Mox from the contralateral prefrontal lobe and the dominant limb were measured by near infrared spectroscopy. During all three contractions, Cbv and Cox increased while Mbv and Mox decreased until fatigue in both genders. There were no signs of levelling off or decline in Cbv and Cox during any of these contractions, implying that there was no reduction in cerebral neuronal activation. Conversely, there was a rapid decline in Mbv and Mox during the early stages of the contractions, with a plateau or slight increase towards the end. The respective delta values at 50%, 75% and 100% of 1RM for Cbv (0·088 versus 0·062 versus 0·070), Cox (0·042 versus 0·033 versus 0·038), Mbv (-0·225 versus -0·198 versus -0·196), and Mox (-0·169 versus -0·146 versus -0·158) were not significantly different in the total group (N=24). These findings suggest that fatigue during resistance exercise lasting up to 60 s is mediated peripherally because of reduced blood volume and oxygen availability and is independent of the type and intensity of muscle contraction and gender.
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Affiliation(s)
- Cristiane Matsuura
- Escola de Educação Física do Exército, Exército Brasileiro, Rio de Janeiro, Brazil
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