1
|
Shadiow J, Miranda ER, Perkins RK, Mazo CE, Lin Z, Lewis KN, Mey JT, Solomon TPJ, Haus JM. Exercise-induced changes to the fiber type-specific redox state in human skeletal muscle are associated with aerobic capacity. J Appl Physiol (1985) 2023; 135:508-518. [PMID: 37471216 PMCID: PMC10538995 DOI: 10.1152/japplphysiol.00662.2022] [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: 11/02/2022] [Revised: 06/23/2023] [Accepted: 07/07/2023] [Indexed: 07/22/2023] Open
Abstract
The benefits of exercise involve skeletal muscle redox state alterations of nicotinamide adenine dinucleotide (NAD) and flavin adenine dinucleotide (FAD). We determined the fiber-specific effects of acute exercise on the skeletal muscle redox state in healthy adults. Muscle biopsies were obtained from 19 participants (11 M, 8 F; 26 ± 4 yr) at baseline (fasted) and 30 min and 3 h after treadmill exercise at 80% maximal oxygen consumption (V̇o2max). Muscle samples were probed for autofluorescence of NADH (excitation at 340-360 nm) and oxidized flavoproteins (Fp; excitation at 440-470 nm) and subsequently, fiber typed to quantify the redox signatures of individual muscle fibers. Redox state was calculated as the oxidation-to-reduction redox ratio: Fp/(Fp + NADH). At baseline, pair-wise comparisons revealed that the redox ratio of myosin heavy chain (MHC) I fibers was 7.2% higher than MHC IIa (P = 0.023, 95% CI: 5.2, 9.2%) and the redox ratio of MHC IIa was 8.0% higher than MHC IIx (P = 0.035, 95% CI: 6.8, 9.2%). MHC I fibers also displayed greater NADH intensity than MHC IIx (P = 0.007) and greater Fp intensity than both MHC IIa (P = 0.019) and MHC IIx (P < 0.0001). Fp intensities increased in all fiber types (main effect, P = 0.039) but redox ratios did not change (main effect, P = 0.483) 30 min after exercise. The change in redox ratio was positively correlated with capillary density in MHC I (rho = 0.762, P = 0.037), MHC IIa fibers (rho = 0.881, P = 0.007), and modestly in MHC IIx fibers (rho = 0. 771, P = 0.103). These findings support the use of redox autofluorescence to interrogate skeletal muscle metabolism.NEW & NOTEWORTHY This study is the first to use autofluorescent imaging to describe differential redox states within human skeletal muscle fiber types with exercise. Our findings highlight an easy and efficacious technique for assessing skeletal muscle redox in humans.
Collapse
Affiliation(s)
- James Shadiow
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Edwin R Miranda
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Ryan K Perkins
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Corey E Mazo
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Zhen Lin
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Kendell N Lewis
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| | - Jacob T Mey
- Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, Louisiana, United States
| | | | - Jacob M Haus
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States
| |
Collapse
|
2
|
Blackwood SJ, Horwath O, Moberg M, Pontén M, Apró W, Ekblom MM, Larsen FJ, Katz A. Extreme Variations in Muscle Fiber Composition Enable Detection of Insulin Resistance and Excessive Insulin Secretion. J Clin Endocrinol Metab 2022; 107:e2729-e2737. [PMID: 35405014 DOI: 10.1210/clinem/dgac221] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Indexed: 12/16/2022]
Abstract
CONTEXT Muscle fiber composition is associated with peripheral insulin action. OBJECTIVE We investigated whether extreme differences in muscle fiber composition are associated with alterations in peripheral insulin action and secretion in young, healthy subjects who exhibit normal fasting glycemia and insulinemia. METHODS Relaxation time following a tetanic contraction was used to identify subjects with a high or low expression of type I muscle fibers: group 1 (n = 11), area occupied by type I muscle fibers = 61.0 ± 11.8%, and group 2 (n = 8), type I area = 36.0 ± 4.9% (P < 0.001). Biopsies were obtained from the vastus lateralis muscle and analyzed for mitochondrial respiration on permeabilized fibers, muscle fiber composition, and capillary density. An intravenous glucose tolerance test was performed and indices of glucose tolerance, insulin sensitivity, and secretion were determined. RESULTS Glucose tolerance was similar between groups, whereas whole-body insulin sensitivity was decreased by ~50% in group 2 vs group 1 (P = 0.019). First-phase insulin release (area under the insulin curve during 10 minutes after glucose infusion) was increased by almost 4-fold in group 2 vs group 1 (P = 0.01). Whole-body insulin sensitivity was correlated with percentage area occupied by type I fibers (r = 0.54; P = 0.018) and capillary density in muscle (r = 0.61; P = 0.005) but not with mitochondrial respiration. Insulin release was strongly related to percentage area occupied by type II fibers (r = 0.93; P < 0.001). CONCLUSIONS Assessment of muscle contractile function in young healthy subjects may prove useful in identifying individuals with insulin resistance and enhanced glucose-stimulated insulin secretion prior to onset of clinical manifestations.
Collapse
Affiliation(s)
- Sarah J Blackwood
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Oscar Horwath
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Marcus Moberg
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Marjan Pontén
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - William Apró
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
- Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden
| | - Maria M Ekblom
- Department of Physical Activity and Health, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Filip J Larsen
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Abram Katz
- Åstrand Laboratory, Department of Physiology, Nutrition and Biomechanics, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| |
Collapse
|
3
|
Nyberg M, Jones AM. Matching of O2 Utilization and O2 Delivery in Contracting Skeletal Muscle in Health, Aging, and Heart Failure. Front Physiol 2022; 13:898395. [PMID: 35774284 PMCID: PMC9237395 DOI: 10.3389/fphys.2022.898395] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 05/05/2022] [Indexed: 12/12/2022] Open
Abstract
Skeletal muscle is one of the most dynamic metabolic organs as evidenced by increases in metabolic rate of >150-fold from rest to maximal contractile activity. Because of limited intracellular stores of ATP, activation of metabolic pathways is required to maintain the necessary rates of ATP re-synthesis during sustained contractions. During the very early phase, phosphocreatine hydrolysis and anaerobic glycolysis prevails but as activity extends beyond ∼1 min, oxidative phosphorylation becomes the major ATP-generating pathway. Oxidative metabolism of macronutrients is highly dependent on the cardiovascular system to deliver O2 to the contracting muscle fibres, which is ensured through a tight coupling between skeletal muscle O2 utilization and O2 delivery. However, to what extent O2 delivery is ideal in terms of enabling optimal metabolic and contractile function is context-dependent and determined by a complex interaction of several regulatory systems. The first part of the review focuses on local and systemic mechanisms involved in the regulation of O2 delivery and how integration of these influences the matching of skeletal muscle O2 demand and O2 delivery. In the second part, alterations in cardiovascular function and structure associated with aging and heart failure, and how these impact metabolic and contractile function, will be addressed. Where applicable, the potential of exercise training to offset/reverse age- and disease-related cardiovascular declines will be highlighted in the context of skeletal muscle metabolic function. The review focuses on human data but also covers animal observations.
Collapse
Affiliation(s)
- Michael Nyberg
- Vascular Biology, Global Drug Discovery, Novo Nordisk A/S, Maaloev, Denmark
- *Correspondence: Michael Nyberg,
| | - Andrew M. Jones
- Department of Sport and Health Sciences, University of Exeter, Exeter, United Kingdom
| |
Collapse
|
4
|
Lavin KM, Coen PM, Baptista LC, Bell MB, Drummer D, Harper SA, Lixandrão ME, McAdam JS, O’Bryan SM, Ramos S, Roberts LM, Vega RB, Goodpaster BH, Bamman MM, Buford TW. State of Knowledge on Molecular Adaptations to Exercise in Humans: Historical Perspectives and Future Directions. Compr Physiol 2022; 12:3193-3279. [PMID: 35578962 PMCID: PMC9186317 DOI: 10.1002/cphy.c200033] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
For centuries, regular exercise has been acknowledged as a potent stimulus to promote, maintain, and restore healthy functioning of nearly every physiological system of the human body. With advancing understanding of the complexity of human physiology, continually evolving methodological possibilities, and an increasingly dire public health situation, the study of exercise as a preventative or therapeutic treatment has never been more interdisciplinary, or more impactful. During the early stages of the NIH Common Fund Molecular Transducers of Physical Activity Consortium (MoTrPAC) Initiative, the field is well-positioned to build substantially upon the existing understanding of the mechanisms underlying benefits associated with exercise. Thus, we present a comprehensive body of the knowledge detailing the current literature basis surrounding the molecular adaptations to exercise in humans to provide a view of the state of the field at this critical juncture, as well as a resource for scientists bringing external expertise to the field of exercise physiology. In reviewing current literature related to molecular and cellular processes underlying exercise-induced benefits and adaptations, we also draw attention to existing knowledge gaps warranting continued research effort. © 2021 American Physiological Society. Compr Physiol 12:3193-3279, 2022.
Collapse
Affiliation(s)
- Kaleen M. Lavin
- Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Center for Human Health, Resilience, and Performance, Institute for Human and Machine Cognition, Pensacola, Florida, USA
| | - Paul M. Coen
- Translational Research Institute for Metabolism and Diabetes, Advent Health, Orlando, Florida, USA
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Liliana C. Baptista
- Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Medicine, Division of Gerontology, Geriatrics and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Margaret B. Bell
- Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Devin Drummer
- Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Sara A. Harper
- Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Medicine, Division of Gerontology, Geriatrics and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Manoel E. Lixandrão
- Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jeremy S. McAdam
- Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Samia M. O’Bryan
- Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Sofhia Ramos
- Translational Research Institute for Metabolism and Diabetes, Advent Health, Orlando, Florida, USA
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Lisa M. Roberts
- Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Medicine, Division of Gerontology, Geriatrics and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Rick B. Vega
- Translational Research Institute for Metabolism and Diabetes, Advent Health, Orlando, Florida, USA
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Bret H. Goodpaster
- Translational Research Institute for Metabolism and Diabetes, Advent Health, Orlando, Florida, USA
- Sanford Burnham Prebys Medical Discovery Institute, Orlando, Florida, USA
| | - Marcas M. Bamman
- Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Cell, Developmental, and Integrative Biology, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Center for Human Health, Resilience, and Performance, Institute for Human and Machine Cognition, Pensacola, Florida, USA
| | - Thomas W. Buford
- Center for Exercise Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, USA
- Department of Medicine, Division of Gerontology, Geriatrics and Palliative Care, The University of Alabama at Birmingham, Birmingham, Alabama, USA
| |
Collapse
|
5
|
Abstract
Since ancient times, the health benefits of regular physical activity/exercise have been recognized and the classic studies of Morris and Paffenbarger provided the epidemiological evidence in support of such an association. Cardiorespiratory fitness, often measured by maximal oxygen uptake, and habitual physical activity levels are inversely related to mortality. Thus, studies exploring the biological bases of the health benefits of exercise have largely focused on the cardiovascular system and skeletal muscle (mass and metabolism), although there is increasing evidence that multiple tissues and organ systems are influenced by regular exercise. Communication between contracting skeletal muscle and multiple organs has been implicated in exercise benefits, as indeed has other interorgan "cross-talk." The application of molecular biology techniques and "omics" approaches to questions in exercise biology has opened new lines of investigation to better understand the beneficial effects of exercise and, in so doing, inform the optimization of exercise regimens and the identification of novel therapeutic strategies to enhance health and well-being.
Collapse
Affiliation(s)
- Mark Hargreaves
- Department of Anatomy & Physiology, The University of Melbourne, Melbourne, Victoria, Australia
| |
Collapse
|
6
|
Jacobs RA, Lundby C. Contextualizing the biological relevance of standardized high-resolution respirometry to assess mitochondrial function in permeabilized human skeletal muscle. Acta Physiol (Oxf) 2021; 231:e13625. [PMID: 33570804 PMCID: PMC8047922 DOI: 10.1111/apha.13625] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 02/08/2021] [Accepted: 02/09/2021] [Indexed: 12/16/2022]
Abstract
Aim This study sought to provide a statistically robust reference for measures of mitochondrial function from standardized high‐resolution respirometry with permeabilized human skeletal muscle (ex vivo), compare analogous values obtained via indirect calorimetry, arterial‐venous O2 differences and 31P magnetic resonance spectroscopy (in vivo) and attempt to resolve differences across complementary methodologies as necessary. Methods Data derived from 831 study participants across research published throughout March 2009 to November 2019 were amassed to examine the biological relevance of ex vivo assessments under standard conditions, ie physiological temperatures of 37°C and respiratory chamber oxygen concentrations of ~250 to 500 μmol/L. Results Standard ex vivo‐derived measures are lower (Z ≥ 3.01, P ≤ .0258) en masse than corresponding in vivo‐derived values. Correcting respiratory values to account for mitochondrial temperatures 10°C higher than skeletal muscle temperatures at maximal exercise (~50°C): (i) transforms data to resemble (Z ≤ 0.8, P > .9999) analogous yet context‐specific in vivo measures, eg data collected during maximal 1‐leg knee extension exercise; and (ii) supports the position that maximal skeletal muscle respiratory rates exceed (Z ≥ 13.2, P < .0001) those achieved during maximal whole‐body exercise, e.g. maximal cycling efforts. Conclusion This study outlines and demonstrates necessary considerations when actualizing the biological relevance of human skeletal muscle respiratory control, metabolic flexibility and bioenergetics from standard ex vivo‐derived assessments using permeabilized human muscle. These findings detail how cross‐procedural comparisons of human skeletal muscle mitochondrial function may be collectively scrutinized in their relationship to human health and lifespan.
Collapse
Affiliation(s)
- Robert A. Jacobs
- Department of Human Physiology & Nutrition University of Colorado Colorado Springs (UCCS) Colorado Springs CO USA
| | - Carsten Lundby
- Innland University of Applied Sciences Lillehammer Norway
| |
Collapse
|
7
|
Cardinale DA, Horwath O, Elings-Knutsson J, Helge T, Godhe M, Bermon S, Moberg M, Flockhart M, Larsen FJ, Hirschberg AL, Ekblom B. Enhanced Skeletal Muscle Oxidative Capacity and Capillary-to-Fiber Ratio Following Moderately Increased Testosterone Exposure in Young Healthy Women. Front Physiol 2020; 11:585490. [PMID: 33343388 PMCID: PMC7745722 DOI: 10.3389/fphys.2020.585490] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 11/10/2020] [Indexed: 11/29/2022] Open
Abstract
Background: Recently, it was shown that exogenously administered testosterone enhances endurance capacity in women. In this study, our understanding on the effects of exogenous testosterone on key determinants of oxygen transport and utilization in skeletal muscle is expanded. Methods: In a double-blinded, randomized, placebo-controlled trial, 48 healthy active women were randomized to 10 weeks of daily application of 10 mg of testosterone cream or placebo. Before and after the intervention, VO2 max, body composition, total hemoglobin (Hb) mass and blood volumes were assessed. Biopsies from the vastus lateralis muscle were obtained before and after the intervention to assess mitochondrial protein abundance, capillary density, capillary-to-fiber (C/F) ratio, and skeletal muscle oxidative capacity. Results: Maximal oxygen consumption per muscle mass, Hb mass, blood, plasma and red blood cell volumes, capillary density, and the abundance of mitochondrial protein levels (i.e., citrate synthase, complexes I, II, III, IV-subunit 2, IV-subunit 4, and V) were unchanged by the intervention. However, the C/F ratio, specific mitochondrial respiratory flux activating complex I and linked complex I and II, uncoupled respiration and electron transport system capacity, but not leak respiration or fat respiration, were significantly increased following testosterone administration compared to placebo. Conclusion: This study provides novel insights into physiological actions of increased testosterone exposure on key determinants of oxygen diffusion and utilization in skeletal muscle of women. Our findings show that higher skeletal muscle oxidative capacity coupled to higher C/F ratio could be major contributing factors that improve endurance performance following moderately increased testosterone exposure.
Collapse
Affiliation(s)
- Daniele A Cardinale
- Department of Physiology, Nutrition and Biomechanics, Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden.,Elite Performance Centre, Bosön - Swedish Sports Confederation, Lidingö, Sweden
| | - Oscar Horwath
- Department of Physiology, Nutrition and Biomechanics, Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Jona Elings-Knutsson
- Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.,Department of Gynaecology and Reproductive Medicine, Karolinska University Hospital, Stockholm, Sweden
| | - Torbjörn Helge
- Department of Physiology, Nutrition and Biomechanics, Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Manne Godhe
- Department of Physiology, Nutrition and Biomechanics, Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | | | - Marcus Moberg
- Department of Physiology, Nutrition and Biomechanics, Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Mikael Flockhart
- Department of Physiology, Nutrition and Biomechanics, Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Filip J Larsen
- Department of Physiology, Nutrition and Biomechanics, Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| | - Angelica Lindén Hirschberg
- 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
- Department of Physiology, Nutrition and Biomechanics, Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| |
Collapse
|
8
|
Skattebo Ø, Calbet JAL, Rud B, Capelli C, Hallén J. Contribution of oxygen extraction fraction to maximal oxygen uptake in healthy young men. Acta Physiol (Oxf) 2020; 230:e13486. [PMID: 32365270 PMCID: PMC7540168 DOI: 10.1111/apha.13486] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 12/16/2022]
Abstract
We analysed the importance of systemic and peripheral arteriovenous O2 difference (
a-v¯O2 difference and a‐vfO2 difference, respectively) and O2 extraction fraction for maximal oxygen uptake (
V˙O2max). Fick law of diffusion and the Piiper and Scheid model were applied to investigate whether diffusion versus perfusion limitations vary with
V˙O2max. Articles (n = 17) publishing individual data (n = 154) on
V˙O2max, maximal cardiac output (
Q˙max; indicator‐dilution or the Fick method),
a-v¯O2 difference (catheters or the Fick equation) and systemic O2 extraction fraction were identified. For the peripheral responses, group‐mean data (articles: n = 27; subjects: n = 234) on leg blood flow (LBF; thermodilution), a‐vfO2 difference and O2 extraction fraction (arterial and femoral venous catheters) were obtained.
Q˙max and two‐LBF increased linearly by 4.9‐6.0 L · min–1 per 1 L · min–1 increase in
V˙O2max (R2 = .73 and R2 = .67, respectively; both P < .001). The
a-v¯O2 difference increased from 118‐168 mL · L–1 from a
V˙O2max of 2‐4.5 L · min–1 followed by a reduction (second‐order polynomial: R2 = .27). After accounting for a hypoxemia‐induced decrease in arterial O2 content with increasing
V˙O2max (R2 = .17; P < .001), systemic O2 extraction fraction increased up to ~90% (
V˙O2max: 4.5 L · min–1) with no further change (exponential decay model: R2 = .42). Likewise, leg O2 extraction fraction increased with
V˙O2max to approach a maximal value of ~90‐95% (R2 = .83). Muscle O2 diffusing capacity and the equilibration index Y increased linearly with
V˙O2max (R2 = .77 and R2 = .31, respectively; both P < .01), reflecting decreasing O2 diffusional limitations and accentuating O2 delivery limitations. In conclusion, although O2 delivery is the main limiting factor to
V˙O2max, enhanced O2 extraction fraction (≥90%) contributes to the remarkably high
V˙O2max in endurance‐trained individuals.
Collapse
Affiliation(s)
- Øyvind Skattebo
- Department of Physical Performance Norwegian School of Sport Sciences Oslo Norway
| | - Jose A. L. Calbet
- Department of Physical Performance Norwegian School of Sport Sciences Oslo Norway
- Department of Physical Education and Research Institute of Biomedical and Health Sciences (IUIBS) University of Las Palmas de Gran Canaria Gran Canaria Spain
| | - Bjarne Rud
- Department of Physical Performance Norwegian School of Sport Sciences Oslo Norway
| | - Carlo Capelli
- Department of Physical Performance Norwegian School of Sport Sciences Oslo Norway
- Department of Neurosciences, Biomedicine and Movement Sciences University of Verona Verona Italy
| | - Jostein Hallén
- Department of Physical Performance Norwegian School of Sport Sciences Oslo Norway
| |
Collapse
|
9
|
Skattebo Ø, Capelli C, Rud B, Auensen M, Calbet JAL, Hallén J. Increased oxygen extraction and mitochondrial protein expression after small muscle mass endurance training. Scand J Med Sci Sports 2020; 30:1615-1631. [PMID: 32403173 DOI: 10.1111/sms.13707] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 04/06/2020] [Accepted: 05/04/2020] [Indexed: 12/14/2022]
Abstract
When exercising with a small muscle mass, the mass-specific O2 delivery exceeds the muscle oxidative capacity resulting in a lower O2 extraction compared with whole-body exercise. We elevated the muscle oxidative capacity and tested its impact on O2 extraction during small muscle mass exercise. Nine individuals conducted six weeks of one-legged knee extension (1L-KE) endurance training. After training, the trained leg (TL) displayed 45% higher citrate synthase and COX-IV protein content in vastus lateralis and 15%-22% higher pulmonary oxygen uptake ( V ˙ O 2 peak ) and peak power output ( W ˙ peak ) during 1L-KE than the control leg (CON; all P < .05). Leg O2 extraction (catheters) and blood flow (ultrasound Doppler) were measured while both legs exercised simultaneously during 2L-KE at the same submaximal power outputs (real-time feedback-controlled). TL displayed higher O2 extraction than CON (main effect: 1.7 ± 1.6% points; P = .010; 40%-83% of W ˙ peak ) with the largest between-leg difference at 83% of W ˙ peak (O2 extraction: 3.2 ± 2.2% points; arteriovenous O2 difference: 7.1 ± 4.8 mL· L-1 ; P < .001). At 83% of W ˙ peak , muscle O2 conductance (DM O2 ; Fick law of diffusion) and the equilibration index Y were higher in TL (P < .01), indicating reduced diffusion limitations. The between-leg difference in O2 extraction correlated with the between-leg ratio of citrate synthase and COX-IV (r = .72-.73; P = .03), but not with the difference in the capillary-to-fiber ratio (P = .965). In conclusion, endurance training improves O2 extraction during small muscle mass exercise by elevating the muscle oxidative capacity and the recruitment of DM O2, especially evident during high-intensity exercise exploiting a larger fraction of the muscle oxidative capacity.
Collapse
Affiliation(s)
- Øyvind Skattebo
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Carlo Capelli
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Bjarne Rud
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Marius Auensen
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Jose A L Calbet
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.,Department of Physical Education, University of Las Palmas de Gran Canaria, Spain.,Research Institute of Biomedical and Health Sciences (IUIBS), Las Palmas de Gran Canaria, Spain
| | - Jostein Hallén
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| |
Collapse
|
10
|
Blood volume expansion does not explain the increase in peak oxygen uptake induced by 10 weeks of endurance training. Eur J Appl Physiol 2020; 120:985-999. [PMID: 32172291 PMCID: PMC7181565 DOI: 10.1007/s00421-020-04336-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 02/25/2020] [Indexed: 12/20/2022]
Abstract
Purpose The endurance training (ET)-induced increases in peak oxygen uptake (\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{V}$$\end{document}V˙O2peak) and cardiac output (\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{Q}$$\end{document}Q˙peak) during upright cycling are reversed to pre-ET levels after removing the training-induced increase in blood volume (BV). We hypothesised that ET-induced improvements in \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{V}$$\end{document}V˙O2peak and \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{Q}$$\end{document}Q˙peak are preserved following phlebotomy of the BV gained with ET during supine but not during upright cycling. Arteriovenous O2 difference (a-\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\bar{\text{v}}$$\end{document}v¯O2diff; \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{V}$$\end{document}V˙O2/\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{Q}$$\end{document}Q˙), cardiac dimensions and muscle morphology were studied to assess their role for the \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{V}$$\end{document}V˙O2peak improvement. Methods Twelve untrained subjects (\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{V}$$\end{document}V˙O2peak: 44 ± 6 ml kg−1 min−1) completed 10 weeks of supervised ET (3 sessions/week). Echocardiography, muscle biopsies, haemoglobin mass (Hbmass) and BV were assessed pre- and post-ET. \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{V}$$\end{document}V˙O2peak and \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{Q}$$\end{document}Q˙peak during upright and supine cycling were measured pre-ET, post-ET and immediately after Hbmass was reversed to the individual pre-ET level by phlebotomy. Results ET increased the Hbmass (3.3 ± 2.9%; P = 0.005), BV (3.7 ± 5.6%; P = 0.044) and \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{V}$$\end{document}V˙O2peak during upright and supine cycling (11 ± 6% and 10 ± 8%, respectively; P ≤ 0.003). After phlebotomy, improvements in \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{V}$$\end{document}V˙O2peak compared with pre-ET were preserved in both postures (11 ± 4% and 11 ± 9%; P ≤ 0.005), as was \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{Q}$$\end{document}Q˙peak (9 ± 14% and 9 ± 10%; P ≤ 0.081). The increased \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{Q}$$\end{document}Q˙peak and a-\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\bar{\text{v}}$$\end{document}v¯O2diff accounted for 70% and 30% of the \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{V}$$\end{document}V˙O2peak improvements, respectively. Markers of mitochondrial density (CS and COX-IV; P ≤ 0.007) and left ventricular mass (P = 0.027) increased. Conclusion The ET-induced increase in \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{V}$$\end{document}V˙O2peak was preserved despite removing the increases in Hbmass and BV by phlebotomy, independent of posture. \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{V}$$\end{document}V˙O2peak increased primarily through elevated \documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\dot{Q}$$\end{document}Q˙peak but also through a widened a-\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$\bar{\text{v}}$$\end{document}v¯O2diff, potentially mediated by cardiac remodelling and mitochondrial biogenesis.
Collapse
|
11
|
Nirengi S, Fuse S, Amagasa S, Homma T, Kime R, Kuroiwa M, Endo T, Sakane N, Matsushita M, Saito M, Kurosawa Y, Hamaoka T. Applicability of Supraclavicular Oxygenated and Total Hemoglobin Evaluated by Near-Infrared Time-Resolved Spectroscopy as Indicators of Brown Adipose Tissue Density in Humans. Int J Mol Sci 2019; 20:ijms20092214. [PMID: 31064052 PMCID: PMC6539985 DOI: 10.3390/ijms20092214] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 04/26/2019] [Accepted: 05/04/2019] [Indexed: 01/13/2023] Open
Abstract
Brown adipose tissue (BAT) may potentially be used in strategies for preventing lifestyle-related diseases. We examine evidence that near-infrared time-resolved spectroscopy (NIRTRS) is capable of estimating human BAT density (BAT-d). The parameters examined in this study are total hemoglobin [total-Hb]sup, oxygenated Hb [oxy-Hb]sup, deoxygenated Hb [deoxy-Hb]sup, Hb O2 saturation (StO2sup), and the reduced scattering coefficient in the supraclavicular region (μs’sup), where BAT deposits can be located; corresponding parameters in the control deltoid region are obtained as controls. Among the NIRTRS parameters, [total-Hb]sup and [oxy-Hb]sup show region-specific increases in winter, compared to summer. Further, [total-Hb]sup and [oxy-Hb]sup are correlated with cold-induced thermogenesis in the supraclavicular region. We conclude that NIRTRS-determined [total-Hb]sup and [oxy-Hb]sup are useful parameters for evaluating BAT-d in a simple, rapid, non-invasive manner.
Collapse
Affiliation(s)
- Shinsuke Nirengi
- Division of Preventive Medicine, National Hospital Organization Kyoto Medical Center, Clinical Research Institute, Kyoto 612-8555, Japan.
| | - Sayuri Fuse
- Department of Sports Medicine for Health Promotion, Tokyo Medical University, Tokyo 160-8402, Japan.
| | - Shiho Amagasa
- Department of Preventive Medicine and Public Health, Tokyo Medical University, Tokyo 160-8402, Japan.
| | - Toshiyuki Homma
- Faculty of Sports and Health Science, Daito Bunka University, Higashimatsuyama-shi, Saitama 355-8501, Japan.
| | - Ryotaro Kime
- Department of Sports Medicine for Health Promotion, Tokyo Medical University, Tokyo 160-8402, Japan.
| | - Miyuki Kuroiwa
- Department of Sports Medicine for Health Promotion, Tokyo Medical University, Tokyo 160-8402, Japan.
| | - Tasuki Endo
- Department of Sports Medicine for Health Promotion, Tokyo Medical University, Tokyo 160-8402, Japan.
| | - Naoki Sakane
- Division of Preventive Medicine, National Hospital Organization Kyoto Medical Center, Clinical Research Institute, Kyoto 612-8555, Japan.
| | - Mami Matsushita
- Department of Nutrition, Tenshi College, Sapporo 065-0013, Japan.
| | | | - Yuko Kurosawa
- Department of Sports Medicine for Health Promotion, Tokyo Medical University, Tokyo 160-8402, Japan.
| | - Takafumi Hamaoka
- Department of Sports Medicine for Health Promotion, Tokyo Medical University, Tokyo 160-8402, Japan.
| |
Collapse
|
12
|
Berg J, Undebakke V, Rasch-Halvorsen Ø, Aakerøy L, Sandbakk Ø, Tjønna AE. Comparison of Mitochondrial Respiration in M. triceps brachii and M. vastus lateralis Between Elite Cross-Country Skiers and Physically Active Controls. Front Physiol 2019; 10:365. [PMID: 31024334 PMCID: PMC6461012 DOI: 10.3389/fphys.2019.00365] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 03/15/2019] [Indexed: 11/13/2022] Open
Abstract
Rationale The main purposes of this study were to compare mitochondrial respiration in M. triceps brachii and M. vastus lateralis between elite cross-country (XC) skiers and physically active controls (CON), and to explore the associations between mitochondrial respiration in these muscles and peak oxygen uptake ( V ˙ O2peak) in arm- and leg-dominant exercise modes. Methods Thirteen male elite XC skiers (age: 25 ± 4; peak oxygen uptake ( V ˙ O2peak): 75.5 ± 4.2 mL⋅kg-1⋅min-1) and twelve CON (age: 26 ± 3; V ˙ O2peak: 57.2 ± 6.4 mL⋅kg-1⋅min-1) had microbiopsies taken from M. vastus lateralis and M. triceps brachii, which were analyzed for various measures of mitochondrial respiration using high-resolution respirometry. Thereafter, all participants tested V ˙ O2peak in both running (RUN) and upper body poling (UBP). Results XC skiers had generally higher mitochondrial respiration in M. triceps brachii compared to CON (P < 0.001), whereas no significant group-differences in mitochondrial respiration in M. vastus lateralis were revealed. XC skiers had higher mitochondrial respiration in M. triceps brachii compared to M. vastus lateralis (P = 0.005-0.058), whereas in CON, most mitochondrial respiration measures were higher in M. vastus lateralis than in M. triceps brachii (P < 0.01). When all athletes were pooled, there was a strong positive correlation between V ˙ O2peak in UBP and mitochondrial respiration in M. triceps brachii on several measures (P < 0.01), whereas no correlation was found for RUN. Conclusion The higher mitochondrial respiration found in M. triceps brachii compared to M. vastus lateralis among our elite XC skiers demonstrates the potential for the arm muscles to adapt to aerobic endurance training. The opposite pattern found in CON, clearly showed lower mitochondrial respiration in M. triceps brachii compared to XC skiers, whereas respiration in M. vastus lateralis did not differ between groups. The strong positive correlation between mitochondrial respiration in M. triceps brachii and V ˙ O2peak in UBP indicate that arm muscles' respiratory function may be a limiting factor for V ˙ O2peak in arm-dominant exercise modes.
Collapse
Affiliation(s)
- Jonathan Berg
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
| | - Vidar Undebakke
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
| | - Øystein Rasch-Halvorsen
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.,Clinic of Thoracic and Occupational Medicine, St. Olav's University Hospital, Trondheim, Norway
| | - Lars Aakerøy
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.,Clinic of Thoracic and Occupational Medicine, St. Olav's University Hospital, Trondheim, Norway
| | - Øyvind Sandbakk
- Centre for Elite Sports Research, Department of Neuromedicine and Movement Science, Norwegian University of Science and Technology, Trondheim, Norway
| | - Arnt Erik Tjønna
- Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway
| |
Collapse
|
13
|
Cardinale DA, Larsen FJ, Jensen-Urstad M, Rullman E, Søndergaard H, Morales-Alamo D, Ekblom B, Calbet JAL, Boushel R. Muscle mass and inspired oxygen influence oxygen extraction at maximal exercise: Role of mitochondrial oxygen affinity. Acta Physiol (Oxf) 2019; 225:e13110. [PMID: 29863764 DOI: 10.1111/apha.13110] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 01/12/2023]
Abstract
AIM We examined the Fick components together with mitochondrial O2 affinity (p50mito ) in defining O2 extraction and O2 uptake during exercise with large and small muscle mass during normoxia (NORM) and hyperoxia (HYPER). METHODS Seven individuals performed 2 incremental exercise tests to exhaustion on a bicycle ergometer (BIKE) and 2 on a 1-legged knee extension ergometer (KE) in NORM or HYPER. Leg blood flow and VO2 were determined by thermodilution and the Fick method. Maximal ADP-stimulated mitochondrial respiration (OXPHOS) and p50mito were measured ex vivo in isolated mitochondria. Mitochondrial excess capacity in the leg was determined from OXPHOS in permeabilized fibres and muscle mass measured with magnetic resonance imaging in relation to peak leg O2 delivery. RESULTS The ex vivo p50mito increased from 0.06 ± 0.02 to 0.17 ± 0.04 kPa with varying substrate supply and O2 flux rates from 9.84 ± 2.91 to 16.34 ± 4.07 pmol O2 ·s-1 ·μg-1 respectively. O2 extraction decreased from 83% in BIKE to 67% in KE as a function of a higher O2 delivery and lower mitochondrial excess capacity. There was a significant relationship between O2 extraction and mitochondrial excess capacity and p50mito that was unrelated to blood flow and mean transit time. CONCLUSION O2 extraction varies with mitochondrial respiration rate, p50mito and O2 delivery. Mitochondrial excess capacity maintains a low p50mito which enhances O2 diffusion from microvessels to mitochondria during exercise.
Collapse
Affiliation(s)
- D. A. Cardinale
- Åstrand Laboratory of Work Physiology; The Swedish School of Sport and Health Sciences; Stockholm Sweden
- Elite Performance Centre; Bosön, Swedish Sports Confederation; Lidingö Sweden
| | - F. J. Larsen
- Åstrand Laboratory of Work Physiology; The Swedish School of Sport and Health Sciences; Stockholm Sweden
| | - M. Jensen-Urstad
- Department of Cardiology; Karolinska Institute; Karolinska University Hospital; Stockholm Sweden
| | - E. Rullman
- Department of Cardiology; Karolinska Institute; Karolinska University Hospital; Stockholm Sweden
- Department of Laboratory Medicine; Clinical Physiology; Karolinska Institutet; Huddinge Sweden
| | - H. Søndergaard
- The Copenhagen Muscle Research Centre; Rigshospitalet; Copenhagen N Denmark
| | - D. Morales-Alamo
- Department of Physical Education; University of Las Palmas de Gran Canaria; Las Palmas de Gran Canaria Spain
- Research Institute of Biomedical and Health Sciences (IUIBS); Las Palmas de Gran Canaria Spain
| | - B. Ekblom
- Åstrand Laboratory of Work Physiology; The Swedish School of Sport and Health Sciences; Stockholm Sweden
| | - J. A. L. Calbet
- Department of Physical Education; University of Las Palmas de Gran Canaria; Las Palmas de Gran Canaria Spain
- Research Institute of Biomedical and Health Sciences (IUIBS); Las Palmas de Gran Canaria Spain
| | - R. Boushel
- Åstrand Laboratory of Work Physiology; The Swedish School of Sport and Health Sciences; Stockholm Sweden
- School of Kinesiology; University of British Columbia; Vancouver BC Canada
| |
Collapse
|
14
|
Acosta FM, Berchem J, Martinez-Tellez B, Sanchez-Delgado G, Alcantara JMA, Ortiz-Alvarez L, Hamaoka T, Ruiz JR. Near-Infrared Spatially Resolved Spectroscopy as an Indirect Technique to Assess Brown Adipose Tissue in Young Women. Mol Imaging Biol 2018; 21:328-338. [DOI: 10.1007/s11307-018-1244-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
15
|
Mitchell CJ, D'Souza RF, Mitchell SM, Figueiredo VC, Miller BF, Hamilton KL, Peelor FF, Coronet M, Pileggi CA, Durainayagam B, Fanning AC, Poppitt SD, Cameron-Smith D. Impact of dairy protein during limb immobilization and recovery on muscle size and protein synthesis; a randomized controlled trial. J Appl Physiol (1985) 2017; 124:717-728. [PMID: 29122965 DOI: 10.1152/japplphysiol.00803.2017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Muscle disuse results in the loss of muscular strength and size, due to an imbalance between protein synthesis (MPS) and breakdown (MPB). Protein ingestion stimulates MPS, although it is not established if protein is able to attenuate muscle loss with immobilization (IM) or influence the recovery consisting of ambulatory movement followed by resistance training (RT). Thirty men (49.9 ± 0.6 yr) underwent 14 days of unilateral leg IM, 14 days of ambulatory recovery (AR), and a further six RT sessions over 14 days. Participants were randomized to consume an additional 20 g of dairy protein or placebo with a meal during the intervention. Isometric knee extension strength was reduced following IM (-24.7 ± 2.7%), partially recovered with AR (-8.6 ± 2.6%), and fully recovered after RT (-0.6 ± 3.4%), with no effect of supplementation. Thigh muscle cross-sectional area decreased with IM (-4.1 ± 0.5%), partially recovered with AR (-2.1 ± 0.5%), and increased above baseline with RT (+2.2 ± 0.5%), with no treatment effect. Myofibrillar MPS, measured using deuterated water, was unaltered by IM, with no effect of protein. During AR, MPS was increased only with protein supplementation. Protein supplementation did not attenuate the loss of muscle size and function with disuse or potentiate recovery but enhanced myofibrillar MPS during AR. NEW & NOTEWORTHY Twenty grams of daily protein supplementation does not attenuate the loss of muscle size and function induced by 2 wk of muscle disuse or potentiate recovery in middle-age men. Average mitochondrial but not myofibrillar muscle protein synthesis was attenuated during immobilization with no effect of supplementation. Protein supplementation increased myofibrillar protein synthesis during a 2-wk period of ambulatory recovery following disuse but without group differences in phenotype recovery.
Collapse
Affiliation(s)
| | - Randall F D'Souza
- Liggins Institute, The University of Auckland , Auckland , New Zealand
| | - Sarah M Mitchell
- Liggins Institute, The University of Auckland , Auckland , New Zealand
| | | | - Benjamin F Miller
- Department of Health and Exercise Science, Colorado State University , Fort Collins, Colorado
| | - Karyn L Hamilton
- Department of Health and Exercise Science, Colorado State University , Fort Collins, Colorado
| | - Fredrick F Peelor
- Department of Health and Exercise Science, Colorado State University , Fort Collins, Colorado
| | - Marcelli Coronet
- Liggins Institute, The University of Auckland , Auckland , New Zealand
| | - Chantal A Pileggi
- Liggins Institute, The University of Auckland , Auckland , New Zealand
| | | | - Aaron C Fanning
- Fonterra Research and Development Centre , Palmerston North , New Zealand
| | - Sally D Poppitt
- School of Biological Sciences, The University of Auckland , Auckland , New Zealand
| | | |
Collapse
|
16
|
Affiliation(s)
- D. A. Cardinale
- Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
- Elite Performance Centre, Bosön - Swedish Sports Confederation, Lidingö, Sweden
| | - B. Ekblom
- Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden
| |
Collapse
|
17
|
Guadalupe-Grau A, Fernández-Elías VE, Ortega JF, Dela F, Helge JW, Mora-Rodriguez R. Effects of 6-month aerobic interval training on skeletal muscle metabolism in middle-aged metabolic syndrome patients. Scand J Med Sci Sports 2017; 28:585-595. [DOI: 10.1111/sms.12881] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/06/2017] [Indexed: 12/20/2022]
Affiliation(s)
- A. Guadalupe-Grau
- Xlab; Department of Biomedical Sciences; Faculty of Health Sciences; Center for Healthy Aging; University of Copenhagen; Copenhagen Denmark
- ImFINE Research Group; Department of Health and Human Performance; Technical University of Madrid; Madrid Spain
| | - V. E. Fernández-Elías
- Exercise Physiology Laboratory at Toledo; University of Castilla-La Mancha; Toledo Spain
- Department of Sport Science; European University of Madrid; Madrid Spain
| | - J. F. Ortega
- Exercise Physiology Laboratory at Toledo; University of Castilla-La Mancha; Toledo Spain
| | - F. Dela
- Xlab; Department of Biomedical Sciences; Faculty of Health Sciences; Center for Healthy Aging; University of Copenhagen; Copenhagen Denmark
| | - J. W. Helge
- Xlab; Department of Biomedical Sciences; Faculty of Health Sciences; Center for Healthy Aging; University of Copenhagen; Copenhagen Denmark
| | - R. Mora-Rodriguez
- Exercise Physiology Laboratory at Toledo; University of Castilla-La Mancha; Toledo Spain
| |
Collapse
|
18
|
van der Zwaard S, de Ruiter CJ, Noordhof DA, Sterrenburg R, Bloemers FW, de Koning JJ, Jaspers RT, van der Laarse WJ. Maximal oxygen uptake is proportional to muscle fiber oxidative capacity, from chronic heart failure patients to professional cyclists. J Appl Physiol (1985) 2016; 121:636-45. [PMID: 27445298 DOI: 10.1152/japplphysiol.00355.2016] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 07/19/2016] [Indexed: 12/25/2022] Open
Abstract
V̇o2 max during whole body exercise is presumably constrained by oxygen delivery to mitochondria rather than by mitochondria's ability to consume oxygen. Humans and animals have been reported to exploit only 60-80% of their mitochondrial oxidative capacity at maximal oxygen uptake (V̇o2 max). However, ex vivo quantification of mitochondrial overcapacity is complicated by isolation or permeabilization procedures. An alternative method for estimating mitochondrial oxidative capacity is via enzyme histochemical quantification of succinate dehydrogenase (SDH) activity. We determined to what extent V̇o2 max attained during cycling exercise differs from mitochondrial oxidative capacity predicted from SDH activity of vastus lateralis muscle in chronic heart failure patients, healthy controls, and cyclists. V̇o2 max was assessed in 20 healthy subjects and 28 cyclists, and SDH activity was determined from biopsy cryosections of vastus lateralis using quantitative histochemistry. Similar data from our laboratory of 14 chronic heart failure patients and 6 controls were included. Mitochondrial oxidative capacity was predicted from SDH activity using estimated skeletal muscle mass and the relationship between ex vivo fiber V̇o2 max and SDH activity of isolated single muscle fibers and myocardial trabecula under hyperoxic conditions. Mitochondrial oxidative capacity predicted from SDH activity was related (r(2) = 0.89, P < 0.001) to V̇o2 max measured during cycling in subjects with V̇o2 max ranging from 9.8 to 79.0 ml·kg(-1)·min(-1) V̇o2 max measured during cycling was on average 90 ± 14% of mitochondrial oxidative capacity. We conclude that human V̇o2 max is related to mitochondrial oxidative capacity predicted from skeletal muscle SDH activity. Mitochondrial oxidative capacity is likely marginally limited by oxygen supply to mitochondria.
Collapse
Affiliation(s)
- Stephan van der Zwaard
- Faculty of Behavioural and Movement Sciences, Department of Human Movement Sciences, Vrije Universiteit Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands;
| | - C Jo de Ruiter
- Faculty of Behavioural and Movement Sciences, Department of Human Movement Sciences, Vrije Universiteit Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands
| | - Dionne A Noordhof
- Faculty of Behavioural and Movement Sciences, Department of Human Movement Sciences, Vrije Universiteit Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands
| | - Renske Sterrenburg
- Faculty of Behavioural and Movement Sciences, Department of Human Movement Sciences, Vrije Universiteit Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands
| | - Frank W Bloemers
- Department of Trauma Surgery, VU University Medical Center Amsterdam, Amsterdam, The Netherlands
| | - Jos J de Koning
- Faculty of Behavioural and Movement Sciences, Department of Human Movement Sciences, Vrije Universiteit Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands
| | - Richard T Jaspers
- Faculty of Behavioural and Movement Sciences, Department of Human Movement Sciences, Vrije Universiteit Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands; Laboratory for Myology, Faculty of Behavioural and Movement Sciences, Vrije Universiteit Amsterdam, MOVE Research Institute Amsterdam, Amsterdam, The Netherlands; and
| | - Willem J van der Laarse
- Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center Amsterdam, Amsterdam, The Netherlands
| |
Collapse
|
19
|
Boushel R, Gnaiger E, Larsen FJ, Helge JW, González-Alonso J, Ara I, Munch-Andersen T, van Hall G, Søndergaard H, Saltin B, Calbet JAL. Maintained peak leg and pulmonary VO2despite substantial reduction in muscle mitochondrial capacity. Scand J Med Sci Sports 2015; 25 Suppl 4:135-43. [DOI: 10.1111/sms.12613] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2015] [Indexed: 01/12/2023]
Affiliation(s)
- R. Boushel
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
- School of Kinesiology; University of British Columbia; Vancouver BC Canada
| | - E. Gnaiger
- Department of Visceral, Transplant and Thoracic Surgery; D. Swarovski Research Laboratory; Medical University of Innsbruck; Innsbruck Austria
| | - F. J. Larsen
- Åstrand Laboratory; The Swedish School of Sport and Health Sciences; Stockholm Sweden
| | - J. W. Helge
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
- X-Lab; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
| | - J. González-Alonso
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
- Centre for Sports Medicine and Human Performance; Brunel University, London; Uxbridge UK
| | - I. Ara
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
- GENUD Toledo Research Group; Universidad de Castilla-La Mancha (UCLM); Spain
| | | | - G. van Hall
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
- Biomedical Sciences, Health & Medical Sciences; University of Copenhagen & Clinical Biochemistry, Rigshospitalet; Copenhagen Denmark
| | - H. Søndergaard
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
| | - B. Saltin
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
| | - J. A. L. Calbet
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
- Department of Physical Education, and Research Institute of Biomedical and Health Sciences (IUIBS); University of Las Palmas de Gran Canaria; Las Palmas Spain
| |
Collapse
|
20
|
Cruz RSDO, de Aguiar RA, Turnes T, Pereira KL, Caputo F. Effects of ischemic preconditioning on maximal constant-load cycling performance. J Appl Physiol (1985) 2015; 119:961-7. [DOI: 10.1152/japplphysiol.00498.2015] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2015] [Accepted: 09/03/2015] [Indexed: 11/22/2022] Open
Abstract
This study investigated the effects of ischemic preconditioning (IPC) on the ratings of perceived exertion (RPE), surface electromyography, and pulmonary oxygen uptake (V̇o2) onset kinetics during cycling until exhaustion at the peak power output attained during an incremental test. A group of 12 recreationally trained cyclists volunteered for this study. After determination of peak power output during an incremental test, they were randomly subjected on different days to a performance protocol preceded by intermittent bilateral cuff pressure inflation to 220 mmHg (IPC) or 20 mmHg (control). To increase data reliability, the performance visits were replicated, also in a random manner. There was an 8.0% improvement in performance after IPC (control: 303 s, IPC 327 s, factor SDs of ×/÷1.13, P = 0.01). This change was followed by a 2.9% increase in peak V̇o2 (control: 3.95 l/min, IPC: 4.06 l/min, factor SDs of ×/÷1.15, P = 0.04), owing to a higher amplitude of the slow component of the V̇o2 kinetics (control: 0.45 l/min, IPC: 0.63 l/min, factor SDs of ×/÷2.21, P = 0.05). There was also an attenuation in the rate of increase in RPE ( P = 0.01) and a progressive increase in the myoelectrical activity of the vastus lateralis muscle ( P = 0.04). Furthermore, the changes in peak V̇o2 ( r = 0.73, P = 0.007) and the amplitude of the slow component ( r = 0.79, P = 0.002) largely correlated with performance improvement. These findings provide a link between improved aerobic metabolism and enhanced severe-intensity cycling performance after IPC. Furthermore, the delayed exhaustion after IPC under lower RPE and higher skeletal muscle activation suggest they have a role on the ergogenic effects of IPC on endurance performance.
Collapse
Affiliation(s)
- Rogério Santos de Oliveira Cruz
- Human Performance Research Group, College of Health and Sport Science, Santa Catarina State University, Florianopolis, Santa Catarina, Brazil
| | - Rafael Alves de Aguiar
- Human Performance Research Group, College of Health and Sport Science, Santa Catarina State University, Florianopolis, Santa Catarina, Brazil
| | - Tiago Turnes
- Human Performance Research Group, College of Health and Sport Science, Santa Catarina State University, Florianopolis, Santa Catarina, Brazil
| | - Kayo Leonardo Pereira
- Human Performance Research Group, College of Health and Sport Science, Santa Catarina State University, Florianopolis, Santa Catarina, Brazil
| | - Fabrizio Caputo
- Human Performance Research Group, College of Health and Sport Science, Santa Catarina State University, Florianopolis, Santa Catarina, Brazil
| |
Collapse
|
21
|
MONTERO DAVID, DIAZ-CAÑESTRO CANDELA, LUNDBY CARSTEN. Endurance Training and V˙O2max. Med Sci Sports Exerc 2015; 47:2024-33. [DOI: 10.1249/mss.0000000000000640] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
|
22
|
Nirengi S, Yoneshiro T, Sugie H, Saito M, Hamaoka T. Human brown adipose tissue assessed by simple, noninvasive near-infrared time-resolved spectroscopy. Obesity (Silver Spring) 2015; 23:973-80. [PMID: 25866030 DOI: 10.1002/oby.21012] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 11/30/2014] [Indexed: 01/30/2023]
Abstract
OBJECTIVE Human brown adipose tissue (BAT) activity has been typically evaluated by (18) F-fluorodeoxyglucose (FDG)-positron emission tomography (PET) combined with computed tomography (CT). However, FDG-PET/CT has serious limitations (e.g., radiation and cold exposure). This study evaluated BAT density using near-infrared time-resolved spectroscopy (NIRTRS ), a simple and noninvasive method of measuring the indices of tissue hemoglobin concentration [total-Hb] and mitochondrial density (µs '). METHODS The NIRTRS parameters at 760, 800, and 830 nm in the supraclavicular region potentially containing BAT were evaluated. First, the NIRTRS parameters were compared at 27 °C and during a 2-h cold exposure (19 °C) in 18 men. Then, NIRTRS parameters at 27 °C were compared with mean standardized uptake values (SUVmean ) assessed by FDG-PET/CT after the 2-h cold exposure (19 °C) in 29 men. RESULTS There was no significant difference between the NIRTRS parameters at 27 °C and 19°C. The [total-Hb] and µs ' were significantly correlated to SUVmean (r = 0.73 and r = 0.64, respectively). A receiver operating characteristic analysis revealed that the sensitivity (75.0-82.4%), specificity (91.7-100%), and accuracy (82.8-86.2%) of the NIRTRS parameters were all good to determine the NIRTRS reliability. CONCLUSIONS Our novel NIRTRS method is noninvasive and simple and can reliably assess human BAT density in the supraclavicular region.
Collapse
Affiliation(s)
- Shinsuke Nirengi
- Graduate School of Sport and Health Science, Ritsumeikan University, Kusatsu, Shiga, Japan
| | | | | | | | | |
Collapse
|
23
|
Boushel R, Lundby C, Qvortrup K, Sahlin K. Mitochondrial plasticity with exercise training and extreme environments. Exerc Sport Sci Rev 2015; 42:169-74. [PMID: 25062000 DOI: 10.1249/jes.0000000000000025] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Mitochondria form a reticulum in skeletal muscle. Exercise training stimulates mitochondrial biogenesis, yet an emerging hypothesis is that training also induces qualitative regulatory changes. Substrate oxidation, oxygen affinity, and biochemical coupling efficiency may be regulated differentially with training and exposure to extreme environments. Threshold training doses inducing mitochondrial upregulation remain to be elucidated considering fitness level.
Collapse
Affiliation(s)
- Robert Boushel
- 1Åstrand Laboratory, The Swedish School of Sport and Health Sciences, Stockholm, Sweden; 2Center for Integrative Human Physiology, Institute of Physiology, University of Zurich, Zurich, Switzerland; and 3Department of Biomedical Sciences, Core Facility for Integrated Microscopy, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | | | | |
Collapse
|
24
|
Booth FW, Ruegsegger GN, Toedebusch RG, Yan Z. Endurance Exercise and the Regulation of Skeletal Muscle Metabolism. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2015; 135:129-51. [DOI: 10.1016/bs.pmbts.2015.07.016] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
25
|
Guadalupe-Grau A, Plenge U, Helbo S, Kristensen M, Andersen PR, Fago A, Belhage B, Dela F, Helge JW. Effects of an 8-weeks erythropoietin treatment on mitochondrial and whole body fat oxidation capacity during exercise in healthy males. J Sports Sci 2014; 33:570-8. [DOI: 10.1080/02640414.2014.951872] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
|
26
|
Boushel R, Ara I, Gnaiger E, Helge JW, González-Alonso J, Munck-Andersen T, Sondergaard H, Damsgaard R, van Hall G, Saltin B, Calbet JAL. Low-intensity training increases peak arm VO2 by enhancing both convective and diffusive O2 delivery. Acta Physiol (Oxf) 2014; 211:122-34. [PMID: 24528535 DOI: 10.1111/apha.12258] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 12/09/2013] [Accepted: 02/07/2014] [Indexed: 11/30/2022]
Abstract
AIM It is an ongoing discussion the extent to which oxygen delivery and oxygen extraction contribute to an increased muscle oxygen uptake during dynamic exercise. It has been proposed that local muscle factors including the capillary bed and mitochondrial oxidative capacity play a large role in prolonged low-intensity training of a small muscle group when the cardiac output capacity is not directly limiting. The purpose of this study was to investigate the relative roles of circulatory and muscle metabolic mechanisms by which prolonged low-intensity exercise training alters regional muscle VO2 . METHODS In nine healthy volunteers (seven males, two females), haemodynamic and metabolic responses to incremental arm cycling were measured by the Fick method and biopsy of the deltoid and triceps muscles before and after 42 days of skiing for 6 h day(-1) at 60% max heart rate. RESULTS Peak pulmonary VO2 during arm crank was unchanged after training (2.38 ± 0.19 vs. 2.18 ± 0.2 L min(-1) pre-training) yet arm VO2 (1.04 ± 0.08 vs. 0.83 ± 0.1 L min(1) , P < 0.05) and power output (137 ± 9 vs. 114 ± 10 Watts) were increased along with a higher arm blood flow (7.9 ± 0.5 vs. 6.8 ± 0.6 L min(-1) , P < 0.05) and expanded muscle capillary volume (76 ± 7 vs. 62 ± 4 mL, P < 0.05). Muscle O2 diffusion capacity (16.2 ± 1 vs. 12.5 ± 0.9 mL min(-1) mHg(-1) , P < 0.05) and O2 extraction (68 ± 1 vs. 62 ± 1%, P < 0.05) were enhanced at a similar mean capillary transit time (569 ± 43 vs. 564 ± 31 ms) and P50 (35.8 ± 0.7 vs. 35 ± 0.8), whereas mitochondrial O2 flux capacity was unchanged (147 ± 6 mL kg min(-1) vs. 146 ± 8 mL kg min(-1) ). CONCLUSION The mechanisms underlying the increase in peak arm VO2 with prolonged low-intensity training in previously untrained subjects are an increased convective O2 delivery specifically to the muscles of the arm combined with a larger capillary-muscle surface area that enhance diffusional O2 conductance, with no apparent role of mitochondrial respiratory capacity.
Collapse
Affiliation(s)
- R. Boushel
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
- The Swedish School of Sport and Health Sciences; Stockholm Sweden
| | - I. Ara
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
- GENUD Toledo Research Group; University of Castilla-La Mancha; Castilla-La Mancha Spain
| | - E. Gnaiger
- D. Swarovski Research Laboratory; Department of Visceral, Transplant and Thoracic Surgery; Medical University of Innsbruck; Innsbruck Austria
| | - J. W. Helge
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
- X-Lab; Department of Biomedical Sciences; University of Copenhagen; Copenhagen Denmark
| | - J. González-Alonso
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
- Centre for Sports Medicine and Human Performance; Brunel University; Uxbridge Middlesex UK
| | | | - H. Sondergaard
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
| | - R. Damsgaard
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
| | - G. van Hall
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
| | - B. Saltin
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
| | - J. A. L. Calbet
- The Copenhagen Muscle Research Centre; Copenhagen Denmark
- Department of Physical Education and Instituto Universitario de Investigaciones Biomédicas y Sanitarias; University of Las Palmas de Gran Canaria; Spain
| |
Collapse
|
27
|
Schlagowski AI, Singh F, Charles AL, Gali Ramamoorthy T, Favret F, Piquard F, Geny B, Zoll J. Mitochondrial uncoupling reduces exercise capacity despite several skeletal muscle metabolic adaptations. J Appl Physiol (1985) 2014; 116:364-75. [DOI: 10.1152/japplphysiol.01177.2013] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The effects of mitochondrial uncoupling on skeletal muscle mitochondrial adaptation and maximal exercise capacity are unknown. In this study, rats were divided into a control group (CTL, n = 8) and a group treated with 2,4-dinitrophenol, a mitochondrial uncoupler, for 28 days (DNP, 30 mg·kg−1·day−1in drinking water, n = 8). The DNP group had a significantly lower body mass ( P < 0.05) and a higher resting oxygen uptake (V̇o2, P < 0.005). The incremental treadmill test showed that maximal running speed and running economy ( P < 0.01) were impaired but that maximal V̇o2(V̇o2max) was higher in the DNP-treated rats ( P < 0.05). In skinned gastrocnemius fibers, basal respiration (V0) was higher ( P < 0.01) in the DNP-treated animals, whereas the acceptor control ratio (ACR, Vmax/V0) was significantly lower ( P < 0.05), indicating a reduction in OXPHOS efficiency. In skeletal muscle, DNP activated the mitochondrial biogenesis pathway, as indicated by changes in the mRNA expression of PGC1-α and -β, NRF-1 and −2, and TFAM, and increased the mRNA expression of cytochrome oxidase 1 ( P < 0.01). The expression of two mitochondrial proteins (prohibitin and Ndufs 3) was higher after DNP treatment. Mitochondrial fission 1 protein (Fis-1) was increased in the DNP group ( P < 0.01), but mitofusin-1 and -2 were unchanged. Histochemical staining for NADH dehydrogenase and succinate dehydrogenase activity in the gastrocnemius muscle revealed an increase in the proportion of oxidative fibers after DNP treatment. Our study shows that mitochondrial uncoupling induces several skeletal muscle adaptations, highlighting the role of mitochondrial coupling as a critical factor for maximal exercise capacities. These results emphasize the importance of investigating the qualitative aspects of mitochondrial function in addition to the amount of mitochondria.
Collapse
Affiliation(s)
- A. I. Schlagowski
- University of Strasbourg, Faculty of Medicine, FMTS, EA 3072, Strasbourg, France
- CHRU of Strasbourg, Physiology and Functional Explorations Department, New Civil Hospital, Strasbourg, France; and
| | - F. Singh
- University of Strasbourg, Faculty of Medicine, FMTS, EA 3072, Strasbourg, France
| | - A. L. Charles
- University of Strasbourg, Faculty of Medicine, FMTS, EA 3072, Strasbourg, France
| | - T. Gali Ramamoorthy
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, Department of Physiological Genetics, Illkirch, France
| | - F. Favret
- University of Strasbourg, Faculty of Medicine, FMTS, EA 3072, Strasbourg, France
- CHRU of Strasbourg, Physiology and Functional Explorations Department, New Civil Hospital, Strasbourg, France; and
| | - F. Piquard
- University of Strasbourg, Faculty of Medicine, FMTS, EA 3072, Strasbourg, France
- CHRU of Strasbourg, Physiology and Functional Explorations Department, New Civil Hospital, Strasbourg, France; and
| | - B. Geny
- University of Strasbourg, Faculty of Medicine, FMTS, EA 3072, Strasbourg, France
- CHRU of Strasbourg, Physiology and Functional Explorations Department, New Civil Hospital, Strasbourg, France; and
| | - J. Zoll
- University of Strasbourg, Faculty of Medicine, FMTS, EA 3072, Strasbourg, France
- CHRU of Strasbourg, Physiology and Functional Explorations Department, New Civil Hospital, Strasbourg, France; and
| |
Collapse
|