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Debold EP, Westerblad H. New insights into the cellular and molecular mechanisms of skeletal muscle fatigue: the Marion J. Siegman Award Lectureships. Am J Physiol Cell Physiol 2024; 327:C946-C958. [PMID: 39069825 DOI: 10.1152/ajpcell.00213.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Revised: 07/11/2024] [Accepted: 07/15/2024] [Indexed: 07/30/2024]
Abstract
Skeletal muscle fibers need to have mechanisms to decrease energy consumption during intense physical exercise to avoid devastatingly low ATP levels, with the formation of rigor cross bridges and defective ion pumping. These protective mechanisms inevitably lead to declining contractile function in response to intense exercise, characterizing fatigue. Through our work, we have gained insights into cellular and molecular mechanisms underlying the decline in contractile function during acute fatigue. Key mechanistic insights have been gained from studies performed on intact and skinned single muscle fibers and more recently from studies performed and single myosin molecules. Studies on intact single fibers revealed several mechanisms of impaired sarcoplasmic reticulum Ca2+ release and experiments on single myosin molecules provide direct evidence of how putative agents of fatigue impact myosin's ability to generate force and motion. We conclude that changes in metabolites due to an increased dependency on anaerobic metabolism (e.g., accumulation of inorganic phosphate ions and H+) act to directly and indirectly (via decreased Ca2+ activation) inhibit myosin's force and motion-generating capacity. These insights into the acute mechanisms of fatigue may help improve endurance training strategies and reveal potential targets for therapies to attenuate fatigue in chronic diseases.
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Affiliation(s)
- Edward P Debold
- Muscle Biophysics Lab, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, United States
| | - Håkan Westerblad
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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Arieta LR, Smith ZH, Paluch AE, Kent JA. Effects of older age on contraction-induced intramyocellular acidosis and inorganic phosphate accumulation in vivo: A systematic review and meta-analysis. PLoS One 2024; 19:e0308336. [PMID: 39321147 PMCID: PMC11424002 DOI: 10.1371/journal.pone.0308336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 07/22/2024] [Indexed: 09/27/2024] Open
Abstract
Although it is clear that the bioenergetic basis of skeletal muscle fatigue (transient decrease in peak torque or power in response to contraction) involves intramyocellular acidosis (decreased pH) and accumulation of inorganic phosphate (Pi) in response to the increased energy demand of contractions, the effects of old age on the build-up of these metabolites has not been evaluated systematically. The purpose of this study was to compare pH and [Pi] in young (18-45 yr) and older (55+ yr) human skeletal muscle in vivo at the end of standardized contraction protocols. Full study details were prospectively registered on PROSPERO (CRD42022348972). PubMed, Web of Science, and SPORTDiscus databases were systematically searched and returned 12 articles that fit the inclusion criteria for the meta-analysis. Participant characteristics, contraction mode (isometric, dynamic), and final pH and [Pi] were extracted. A random-effects model was used to calculate the mean difference (MD) and 95% confidence interval (CI) for pH and [Pi] across age groups. A subgroup analysis for contraction mode was also performed. Young muscle acidified more than older muscle (MD = -0.12 pH; 95%CI = -0.18,-0.06; p<0.01). There was no overall difference by age in final [Pi] (MD = 2.14 mM; 95%CI = -0.29,4.57; p = 0.08), although sensitivity analysis revealed that removing one study resulted in greater [Pi] in young than older muscle (MD = 3.24 mM; 95%CI = 1.72,4.76; p<0.01). Contraction mode moderated these effects (p = 0.02) such that young muscle acidified (MD = -0.19 pH; 95%CI = -0.27,-0.11; p<0.01) and accumulated Pi (MD = 4.69 mM; 95%CI = 2.79,6.59; p<0.01) more than older muscle during isometric, but not dynamic, contractions. The smaller energetic perturbation in older muscle indicated by these analyses is consistent with its relatively greater use of oxidative energy production. During dynamic contractions, elimination of this greater reliance on oxidative energy production and consequently lower metabolite accumulations in older muscle may be important for understanding task-specific, age-related differences in fatigue.
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Affiliation(s)
- Luke R Arieta
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
| | - Zoe H Smith
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
| | - Amanda E Paluch
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
- Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA, United States of America
| | - Jane A Kent
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
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Sears KN, Montgomery TR, Kipper CW, Kis P, Dinyer-McNeely TK, Hammer SM. Muscle microvascular oxygen delivery limitations during the contraction phase of intermittent maximal effort contractions. Eur J Appl Physiol 2024:10.1007/s00421-024-05605-0. [PMID: 39251444 DOI: 10.1007/s00421-024-05605-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2024] [Accepted: 08/30/2024] [Indexed: 09/11/2024]
Abstract
PURPOSE The end-test torque (ETT) during intermittent maximal effort contractions reflects the highest contraction intensity at which a muscle metabolic steady-state can be attained. This study determined if ETT is the highest intensity at which the contraction phase of intermittent exercise does not limit the matching of microvascular oxygen delivery to muscle oxygen demand. METHODS Microvascular oxygenation characteristics of the biceps brachii muscle were measured in sixteen young, healthy individuals (8M/8F, 22 ± 3 years, 80.9 ± 20.3 kg) by near-infrared spectroscopy during maximal effort elbow flexion under control conditions (CON) and with complete circulatory occlusion (OCC). RESULTS Increases in total-[heme] were blunted during OCC compared to CON (225 ± 87 vs. 264 ± 88 μM, p < 0.001) but OCC did not elicit a compensatory increase in deoxygenated-[heme] at any timepoint (108 ± 62 vs. 101 ± 61 μM, p > 0.05). Deoxygenated-[heme] was significantly elevated during contraction, relative to relaxation, above ETT (107 ± 60 vs. 98.8 ± 60.5 μM, p < 0.001), but not at ETT (91.7 ± 54.1 vs. 98.4 ± 62.2 μM, p = 0.174). Total-[heme] was significantly reduced during contraction, relative to relaxation, at all contraction intensities during CON (p < 0.05) and OCC (p < 0.05). CONCLUSION These data suggest that ETT may reflect the highest contraction intensity at which contraction-induced increases in intramuscular pressures do not limit muscle perfusion to a degree that requires further increases in fractional oxygen extraction (i.e., deoxygenated-[heme]) despite limited microvascular diffusive conductance (i.e., total-[heme]).
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Affiliation(s)
- Kylie N Sears
- School of Kinesiology, Applied Health, and Recreation, Oklahoma State University, 180 Colvin Recreation Center, Stillwater, OK, 74078, USA
| | - Tony R Montgomery
- School of Kinesiology, Applied Health, and Recreation, Oklahoma State University, 180 Colvin Recreation Center, Stillwater, OK, 74078, USA
| | - Colin W Kipper
- School of Kinesiology, Applied Health, and Recreation, Oklahoma State University, 180 Colvin Recreation Center, Stillwater, OK, 74078, USA
| | - Petra Kis
- School of Kinesiology, Applied Health, and Recreation, Oklahoma State University, 180 Colvin Recreation Center, Stillwater, OK, 74078, USA
| | - Taylor K Dinyer-McNeely
- School of Kinesiology, Applied Health, and Recreation, Oklahoma State University, 180 Colvin Recreation Center, Stillwater, OK, 74078, USA
| | - Shane M Hammer
- School of Kinesiology, Applied Health, and Recreation, Oklahoma State University, 180 Colvin Recreation Center, Stillwater, OK, 74078, USA.
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Fenuta AM, Drouin PJ, Kohoko ZIN, Lynn MJT, Tschakovsky ME. Influence of acute dietary nitrate supplementation on oxygen delivery/consumption and critical impulse during maximal effort forearm exercise in males: a randomized crossover trial. Appl Physiol Nutr Metab 2024; 49:1184-1201. [PMID: 38728747 DOI: 10.1139/apnm-2023-0606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2024]
Abstract
Beetroot juice supplementation (BRJ) should increase nitric oxide bioavailability under conditions of muscle deoxygenation and acidosis that are a normal consequence of the maximal effort exercise test used to identify forearm critical impulse. We hypothesized BRJ would improve oxygen delivery:demand matching and forearm critical impulse performance. Healthy males (20.8 ± 2.4 years) participated in a randomized crossover trial between October 2017 and May 2018 (Queen's University, Kingston, ON). Participants completed 10 min of rhythmic maximal effort forearm handgrip exercise 2.5 h post placebo (PL) vs. BRJ (9 completed PL/BRJ vs. 4 completed BRJ/PL) within a 2 week period. Data are presented as mean ± SD. There was a main effect of drink (PL > BRJ) for oxygen extraction (P = 0.033, ηp2 = 0.351) and oxygen consumption/force (P = 0.017, ηp2 = 0.417). There was a drink × time interaction (PL > BRJ) for oxygen consumption/force (P = 0.035, ηp2 = 0.216) between 75 and 360 s (1.25-6 min) from exercise onset. BRJ did not influence oxygen delivery (P = 0.953, ηp2 = 0.000), oxygen consumption (P = 0.064, ηp2 = 0.278), metabolites ((lactate) (P = 0.196, ηp2 = 0.135), pH (P = 0.759, ηp2 = 0.008)) or power-duration performance parameters (critical impulse (P = 0.379, d = 0.253), W' (P = 0.733, d = 0.097)). BRJ during all-out handgrip exercise does not influence oxygen delivery or exercise performance. Oxygen cost of contraction with BRJ is reduced as contraction impulse is declining during maximal effort exercise resulting in less oxygen extraction.
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Affiliation(s)
- Alyssa M Fenuta
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada
| | - Patrick J Drouin
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada
| | - Zach I N Kohoko
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada
| | - Mytchel J T Lynn
- School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada
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Flensted-Jensen M, Kleis-Olsen AS, Hassø RK, Lindtofte S, Corral Pérez J, Ortega-Gómez S, Larsen S. Combined changes in temperature and pH mimicking exercise result in decreased efficiency in muscle mitochondria. J Appl Physiol (1985) 2024; 136:79-88. [PMID: 37969081 DOI: 10.1152/japplphysiol.00293.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 11/07/2023] [Accepted: 11/10/2023] [Indexed: 11/17/2023] Open
Abstract
It is well known that exercise efficiency declines at intensities above the lactate threshold, yet the underlying mechanisms are poorly understood. Some have suggested it is due to a decline in mitochondrial efficiency, but this is difficult to examine in vivo. Therefore, the aim of the current study was to examine how changes in temperature and pH, mimicking those that occur during exercise, affect mitochondrial efficiency in skeletal muscle mitochondria. This study was performed on quadriceps muscle of 20 wild-type mice. Muscle tissue was dissected and either permeabilized (n = 10) or homogenized for isolation of mitochondria (n = 10), and oxidative phosphorylation capacity and P/O ratio were assessed using high-resolution respirometry. Samples from each muscle were analyzed in both normal physiological conditions (37°C, pH 7.4), decreased pH (6.8), increased temperature (40°C), and a combination of both. The combination of increased temperature and decreased pH resulted in a significantly lower P/O ratio, mirrored by an increase in leak respiration and a decrease in respiratory control ratio (RCR), in isolated mitochondria. In permeabilized fibers, RCR and leak were relatively unaffected, though a main effect of temperature was observed. Oxidative phosphorylation capacity was unaffected by changes in pH and temperature in both isolated mitochondria and permeabilized fibers. These results indicate that exercise-like changes in temperature and pH lead to impaired mitochondrial efficiency. These findings offer some degree of support to the concept of decreased mitochondrial efficiency during exercise, and may have implications for the assessment of mitochondrial function related to exercise.NEW & NOTEWORTHY To the best of our knowledge, this is the first study to examine the effects of combined changes in temperature and pH, mimicking intramuscular alterations during exercise. Our findings suggest that mitochondrial efficiency is impaired during exercise of moderate to high intensity, which could be a possible mechanism contributing to the decline in exercise efficiency at intensities above the lactate threshold.
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Affiliation(s)
- Mathias Flensted-Jensen
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ann-Sofie Kleis-Olsen
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rasmus Kinimond Hassø
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Søren Lindtofte
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Juan Corral Pérez
- MOVE-IT Research Group, Department of Physical Education, Faculty of Education Sciences, University of Cádiz, Cádiz, Spain
- ExPhy Research Group, Department of Physical Education, Instituto de Investigación e Innovación Biomédica de Cádiz (INiBICA), Universidad de Cádiz, Cádiz, Spain
| | - Sonia Ortega-Gómez
- MOVE-IT Research Group, Department of Physical Education, Faculty of Education Sciences, University of Cádiz, Cádiz, Spain
- Biomedical Research and Innovation Institute of Cádiz (INiBICA) Research Unit, Puerta del Mar University Hospital, Cádiz, Spain
| | - Steen Larsen
- Xlab, Center for Healthy Aging, Department of Biomedical Sciences, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
- Clinical Research Centre, Medical University of Bialystok, Bialystok, Poland
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Fenuta AM, Drouin PJ, Kohoko ZIN, Lynn MJT, Tschakovsky ME. Does a single bout maximal effort forearm exercise test for determining critical impulse result in maximal oxygen delivery and consumption in men? A randomized crossover trial. Appl Physiol Nutr Metab 2023; 48:293-306. [PMID: 36645882 DOI: 10.1139/apnm-2022-0317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In a single bout maximal effort isometric forearm handgrip exercise test (maximal effort exercise test, MXT), contraction impulse exhibits exponential decay to an asymptote equivalent to critical impulse (CI). It is unknown whether oxygen delivery (O2del) and consumption (V˙O2) achieved at CI are maximal. Healthy men participated in a randomized crossover trial at Queen's University (Kingston, ON) between October 2017-May 2018. Participants completed an MXT and forearm incremental exercise test to limit of tolerance (IET-LOT) (7 completed MXT followed by IET-LOT vs. 4 completed IET-LOT followed by MXT) within a 2 week period. Data are presented as mean ± standard deviation. Maximal forearm blood flow (FBF) and O2del were not different in 11 men (21 ± 2.5 years) between MXT and IET-LOT (FBF = 473.8 ± 132.2 mL/min vs. 502.3 ± 152.3 mL/min; P = 0.482, ηp2 = 0.015; O2del = 85.2 ± 23.5 mL/min vs. 92.2 ± 37.0 mL/min; P = 0.456, ηp2 = 0.012). However, MXT resulted in greater maximal V˙O2 than IET-LOT (44.5 ± 15.2 mL/min > 36.8 ± 11.4 mL/min; P = 0.007, ηp2 = 0.09), due to greater oxygen extraction (54.0 ± 10.0% > 44.4 ± 8.6%; P = 0.021, ηp2 = 0.185). As CI was 88.6 ± 8.2% of IET-LOT contraction impulse, maximal O2 cost of contractions in MXT was greater than IET-LOT (0.45 ± 0.14 mL/min/Ns > 0.33 ± 0.09 mL/min/Ns; P < 0.001, ηp2 = 0.166). In healthy men, MXT identifying CI results in similar peak oxygen delivery but greater peak V˙O2 via increased extraction compared to an IET-LOT, indicating increased oxygen cost. MXT-CI may better estimate maximal V˙O2 than traditional IET-LOT for this exercise modality.
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Affiliation(s)
- Alyssa M Fenuta
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Patrick J Drouin
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Zach I N Kohoko
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Mytchel J T Lynn
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, K7L 3N6, Canada
| | - Michael E Tschakovsky
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ontario, K7L 3N6, Canada
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Massamba A, Hucteau E, Mallard J, Ducrocq GP, Favret F, Hureau TJ. Exercise-Induced Fatigue in Hamstring versus Quadriceps Muscles and Consequences on the Torque-Duration Relationship in Men. Med Sci Sports Exerc 2022; 54:2099-2108. [PMID: 35868018 DOI: 10.1249/mss.0000000000003007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The present study investigated the mechanisms of neuromuscular fatigue in quadriceps and hamstring muscles and its consequences on the torque-duration relationship. METHODS Twelve healthy men performed a 5-min all-out exercise (3-s contraction, 2-s relaxation) with either quadriceps or hamstring muscles on separate days. Central fatigue and peripheral fatigue were quantified via changes in pre- to postexercise voluntary activation (VA) and potentiated twitch (P Tw ) torque evoked by supramaximal electrical stimulation, respectively. Critical torque was determined as the mean torque of the last six contractions, whereas W ' was calculated as the torque impulse done above critical torque. RESULTS After exercise, maximal voluntary contraction (MVC) decreased to a greater magnitude ( P < 0.001) in quadriceps (-67% ± 9%) compared with hamstring (-51% ± 10%). ∆P Tw was also greater in quadriceps compared with hamstring (-69% ± 15% vs 55% ± 10%, P < 0.01), whereas central fatigue only developed in quadriceps (∆VA, -25% ± 28%). Hamstring demonstrated reduced critical torque compared with quadriceps (60 ± 12 vs 97 ± 26 N·m, P < 0.001) as well as drastically lower W ' (1001 ± 696 vs 8111 ± 2073 N·m·s, P < 0.001). No correlation was found between quadriceps and hamstring for any index of neuromuscular fatigue (∆MVC, ∆P Tw , or ∆VA). CONCLUSIONS These findings revealed that hamstring presented different etiology and magnitude of neuromuscular fatigue compared with quadriceps. The absence of correlation observed between quadriceps and hamstring fatigue parameters (∆MVC, ∆P Tw , or ∆VA) suggests no interrelation in fatigue etiology between these two muscle groups within individuals and, therefore, highlights the need to investigate specifically hamstring muscle fatigue.
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Bordoni B. Comment on: The Effect of Pedal Pump Lymphatic Technique Versus Passive Recovery Following Maximal Exercise: A Randomized Cross-Over Trial. SPORTS MEDICINE - OPEN 2022; 8:51. [PMID: 35404022 PMCID: PMC9001765 DOI: 10.1186/s40798-022-00443-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 03/27/2022] [Indexed: 11/30/2022]
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Laginestra FG, Cavicchia A, Vanegas-Lopez JE, Barbi C, Martignon C, Giuriato G, Pedrinolla A, Amann M, Hureau TJ, Venturelli M. Prior Involvement of Central Motor Drive Does Not Impact Performance and Neuromuscular Fatigue in a Subsequent Endurance Task. Med Sci Sports Exerc 2022; 54:1751-1760. [PMID: 35612382 PMCID: PMC9481724 DOI: 10.1249/mss.0000000000002965] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE This study evaluated whether central motor drive during fatiguing exercise plays a role in determining performance and the development of neuromuscular fatigue during a subsequent endurance task. METHODS On separate days, 10 males completed three constant-load (80% peak power output), single-leg knee-extension trials to task failure in a randomized fashion. One trial was performed without preexisting quadriceps fatigue (CON), and two trials were performed with preexisting quadriceps fatigue induced either by voluntary (VOL; involving central motor drive) or electrically evoked (EVO; without central motor drive) quadriceps contractions (~20% maximal voluntary contraction (MVC)). Neuromuscular fatigue was assessed via pre-post changes in MVC, voluntary activation (VA), and quadriceps potentiated twitch force ( Qtw,pot ). Cardiorespiratory responses and rating of perceived exertion were also collected throughout the sessions. The two prefatiguing protocols were matched for peripheral fatigue and stopped when Qtw,pot declined by ~35%. RESULTS Time to exhaustion was shorter in EVO (4.3 ± 1.3 min) and VOL (4.7 ± 1.5 min) compared with CON (10.8 ± 3.6 min, P < 0.01) with no difference between EVO and VOL. ΔMVC (EVO: -47% ± 8%, VOL: -45% ± 8%, CON: -53% ± 8%), Δ Qtw,pot (EVO: -65% ± 7%, VOL: -59% ± 14%, CON: -64% ± 9%), and ΔVA (EVO: -9% ± 7%, VOL: -8% ± 5%, CON: -7% ± 5%) at the end of the dynamic task were not different between conditions (all P > 0.05). Compared with EVO (10.6 ± 1.7) and CON (6.8 ± 0.8), rating of perceived exertion was higher ( P = 0.05) at the beginning of VOL (12.2 ± 1.0). CONCLUSIONS These results suggest that central motor drive involvement during prior exercise plays a negligible role on the subsequent endurance performance. Therefore, our findings indicate that peripheral fatigue-mediated impairments are the primary determinants of high-intensity single-leg endurance performance.
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Affiliation(s)
| | - Alessandro Cavicchia
- Department of Neuroscience, Biomedicine, and Movement, University of Verona, ITALY
| | - Jennifer E. Vanegas-Lopez
- Faculty of Medicine, Mitochondria, Oxidative Stress and Muscular Protection Laboratory, University of Strasbourg, FRANCE
| | - Chiara Barbi
- Department of Neuroscience, Biomedicine, and Movement, University of Verona, ITALY
| | - Camilla Martignon
- Department of Neuroscience, Biomedicine, and Movement, University of Verona, ITALY
| | - Gaia Giuriato
- Department of Neuroscience, Biomedicine, and Movement, University of Verona, ITALY
| | - Anna Pedrinolla
- Department of Neuroscience, Biomedicine, and Movement, University of Verona, ITALY
| | - Markus Amann
- Department of Anaesthesiology, University of Utah, Salt Lake City, Utah
| | - Thomas J. Hureau
- Faculty of Medicine, Mitochondria, Oxidative Stress and Muscular Protection Laboratory, University of Strasbourg, FRANCE
| | - Massimo Venturelli
- Department of Neuroscience, Biomedicine, and Movement, University of Verona, ITALY
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du Plessis C, Andrews M, Mitchell LJG, Cochrane Wilkie J, King T, Blazevich AJ. Shorter constant work rate cycling tests as proxies for longer tests in highly trained cyclists. PLoS One 2022; 17:e0259034. [PMID: 35604957 PMCID: PMC9126395 DOI: 10.1371/journal.pone.0259034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 03/23/2022] [Indexed: 11/29/2022] Open
Abstract
Severe-intensity constant work rate (CWR) cycling tests simulate the high-intensity competition environment and are useful for monitoring training progression and adaptation, yet impose significant physiological and psychological strain, require substantial recovery, and may disrupt athlete training or competition preparation. A brief, minimally fatiguing test providing comparable information is desirable. Purpose To determine whether physiological variables measured during, and functional decline in maximal power output immediately after, a 2-min CWR test can act as a proxy for 4-min test outcomes. Methods Physiological stress ( V˙O2 kinetics, heart rate, blood lactate concentrations ([La-]b)) was monitored and performance fatigability was estimated (as pre-to-post-CWR changes in 10-s sprint power) during 2- and 4-min CWR tests in 16 high-level cyclists ( V˙O2peak=64.4±6.0 ml∙kg-1∙min-1). The relationship between the 2- and 4-min CWR tests and the physiological variables that best relate to the performance fatigability were investigated. Results The 2-min CWR test evoked a smaller decline in sprint mechanical power (32% vs. 47%, p<0.001). Both the physiological variables (r = 0.66–0.96) and sprint mechanical power (r = 0.67–0.92) were independently and strongly correlated between 2- and 4-min tests. Differences in V˙O2peak and [La-]b in both CWR tests were strongly associated with the decline in sprint mechanical power. Conclusion Strong correlations between 2- and 4-min severe-intensity CWR test outcomes indicated that the shorter test can be used as a proxy for the longer test. A shorter test may be more practical within the elite performance environment due to lower physiological stress and performance fatigability and should have less impact on subsequent training and competition preparation.
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Affiliation(s)
- Chantelle du Plessis
- Centre of Human Performance, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
- Performance Science Unit, Queensland Academy of Sport, Nathan, Queensland, Australia
- Queensland Academy of Sport, Sport Performance Innovation and Knowledge Excellence, Nathan, Queensland, Australia
- * E-mail:
| | - Mark Andrews
- Performance Science Unit, Queensland Academy of Sport, Nathan, Queensland, Australia
| | | | - Jodie Cochrane Wilkie
- Centre of Human Performance, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
| | - Trish King
- Performance Science Unit, Queensland Academy of Sport, Nathan, Queensland, Australia
| | - Anthony J. Blazevich
- Centre of Human Performance, School of Medical and Health Sciences, Edith Cowan University, Joondalup, Western Australia, Australia
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Hureau TJ, Broxterman RM, Weavil JC, Lewis MT, Layec G, Amann M. On the role of skeletal muscle acidosis and inorganic phosphates as determinants of central and peripheral fatigue: A 31 P-MRS study. J Physiol 2022; 600:3069-3081. [PMID: 35593645 DOI: 10.1113/jp283036] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2022] [Accepted: 04/28/2022] [Indexed: 01/20/2023] Open
Abstract
Intramuscular hydrogen ion (H+ ) and inorganic phosphate (Pi) concentrations were dissociated during exercise to challenge their relationships with peripheral and central fatigue in vivo. Ten recreationally active, healthy men (27 ± 5 years; 180 ± 4 cm; 76 ± 10 kg) performed two consecutive intermittent isometric single-leg knee-extensor trials (60 maximal voluntary contractions; 3 s contraction, 2 s relaxation) interspersed with 5 min of rest. Phosphorus magnetic resonance spectroscopy (31 P-MRS) was used to continuously quantify intramuscular [H+ ] and [Pi] during both trials. Using electrical femoral nerve stimulation, quadriceps twitch force (Qtw ) and voluntary activation (VA) were quantified at rest and throughout both trials. Decreases in Qtw and VA from baseline were used to determine peripheral and central fatigue, respectively. Qtw was strongly related to both [H+ ] (β coefficient: -0.9, P < 0.0001) and [Pi] (-1.1, P < 0.0001) across trials. There was an effect of trial on the relationship between Qtw and [H+ ] (-0.5, P < 0.0001), but not Qtw and [Pi] (0.0, P = 0.976). This suggests that, unlike the unaltered association with [Pi], a given level of peripheral fatigue was associated with a different [H+ ] in Trial 1 vs. Trial 2. VA was related to [H+ ] (-0.3, P < 0.0001), but not [Pi] (-0.2, P = 0.243), across trials and there was no effect of trial (-0.1, P = 0.483). Taken together, these results support intramuscular Pi as a primary cause of peripheral fatigue, and muscle acidosis, probably acting on group III/IV muscle afferents in the interstitial space, as a contributor to central fatigue during exercise. KEY POINTS: We investigated the relationship between intramuscular metabolites and neuromuscular function in humans performing two maximal, intermittent, knee-extension trials interspersed with 5 min of rest. Concomitant measurements of intramuscular hydrogen (H+ ) and inorganic phosphate (Pi) concentrations, as well as quadriceps twitch-force (Qtw ) and voluntary activation (VA), were made throughout each trial using phosphorus magnetic resonance spectroscopy (31 P-MRS) and electrical femoral nerve stimulations. Although [Pi] fully recovered prior to the onset of the second trial, [H+ ] did not. Qtw was strongly related to both [H+ ] and [Pi] across both trials. However, the relationship between Qtw and [H+ ] shifted leftward from the first to the second trial, whereas the relationship between Qtw and [Pi] remained unaltered. VA was related to [H+ ], but not [Pi], across both trials. These in vivo findings support the hypotheses of intramuscular Pi as a primary cause of peripheral fatigue, and muscle acidosis, probably acting on group III/IV muscle afferents, as a contributor to central fatigue.
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Affiliation(s)
- Thomas J Hureau
- Department of Medicine, University of Utah, Salt Lake City, UT, USA.,University of Strasbourg, Faculty of Sport Sciences, UR 3072: Mitochondria, Oxidative Stress and Muscular Protection Laboratory, Strasbourg, France
| | - Ryan M Broxterman
- Department of Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City, UT, VAMC, USA
| | - Joshua C Weavil
- Department of Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City, UT, VAMC, USA
| | - Matthew T Lewis
- Department of Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City, UT, VAMC, USA
| | - Gwenael Layec
- Department of Medicine, University of Utah, Salt Lake City, UT, USA
| | - Markus Amann
- Department of Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City, UT, VAMC, USA.,Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
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12
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Saif A, Khan Z, Parveen A. Critical power as a fatigue threshold in sports: A scoping review. Sci Sports 2022. [DOI: 10.1016/j.scispo.2021.05.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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13
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Hebisz RG, Hebisz P, Zatoń MW. Heart Rate Variability After Sprint Interval Training in Cyclists and Implications for Assessing Physical Fatigue. J Strength Cond Res 2022; 36:558-564. [PMID: 32304516 PMCID: PMC8785771 DOI: 10.1519/jsc.0000000000003549] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
ABSTRACT Hebisz, RG, Hebisz, P, and Zatoń, MW. Heart rate variability after sprint interval training in cyclists and implications for assessing physical fatigue. J Strength Cond Res 36(2): 558-564, 2022-This study evaluated the time- and frequency-domain indexes of heart rate variability (HRV) during sprint interval exercise test (SIXT) and identify the onset of fatigue by HRV concurrent with changes in average (Pavg) and peak (Ppeak) power output, total oxygen uptake (V̇o2tou), and blood hydrogen (H+) and lactate (La-) concentrations. Twenty-seven cyclists performed 4 sets of SIXT in which each set consisted of four 30-second maximal sprints interspersed with 90 seconds of low-intensity cycling. Each set was separated by 25-40 minutes of recovery. Before beginning each set, HRV was analyzed by time (mean normal-to-normal RR intervals [RRNN], SD of normal-to-normal RR intervals [SDNN], and square root of the mean squared difference between successive normal-to-normal RR intervals [RMSSD]) and frequency (total spectral power [T] and very low- [VLF], low- [LF], and high-frequency [HF] spectral power) domain methods. Pavg, Ppeak, and V̇o2tou were recorded in each set, and H+ and La- were measured after each set. RRNN, SDNN, and VLF decreased in the second set, whereas all time and frequency indexes of HRV decreased in the third and fourth set. Pavg and H+ decreased, while V̇o2tou increased in the fourth set. Ppeak decreased in the second, third, and fourth set. Correlations were found between the changes in the time and frequency indexes of HRV with H+, La-, and V̇o2tou. The results indicate that HRV does not reflect the onset of physical fatigue in SIXT as was observed in Pavg and no correlation was found between the changes in HRV with Pavg and Ppeak.
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Affiliation(s)
- Rafał G Hebisz
- Department of Physiology and Biochemistry, University School of Physical Education, Wroclaw, Poland
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14
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Lewis MT, Blain GM, Hart CR, Layec G, Rossman MJ, Park SY, Trinity JD, Gifford JR, Sidhu SK, Weavil JC, Hureau TJ, Jessop JE, Bledsoe AD, Amann M, Richardson RS. Acute high-intensity exercise and skeletal muscle mitochondrial respiratory function: role of metabolic perturbation. Am J Physiol Regul Integr Comp Physiol 2021; 321:R687-R698. [PMID: 34549627 DOI: 10.1152/ajpregu.00158.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Recently it was documented that fatiguing, high-intensity exercise resulted in a significant attenuation in maximal skeletal muscle mitochondrial respiratory capacity, potentially due to the intramuscular metabolic perturbation elicited by such intense exercise. With the utilization of intrathecal fentanyl to attenuate afferent feedback from group III/IV muscle afferents, permitting increased muscle activation and greater intramuscular metabolic disturbance, this study aimed to better elucidate the role of metabolic perturbation on mitochondrial respiratory function. Eight young, healthy males performed high-intensity cycle exercise in control (CTRL) and fentanyl-treated (FENT) conditions. Liquid chromatography-mass spectrometry and high-resolution respirometry were used to assess metabolites and mitochondrial respiratory function, respectively, pre- and postexercise in muscle biopsies from the vastus lateralis. Compared with CTRL, FENT yielded a significantly greater exercise-induced metabolic perturbation (PCr: -67% vs. -82%, Pi: 353% vs. 534%, pH: -0.22 vs. -0.31, lactate: 820% vs. 1,160%). Somewhat surprisingly, despite this greater metabolic perturbation in FENT compared with CTRL, with the only exception of respiratory control ratio (RCR) (-3% and -36%) for which the impact of FENT was significantly greater, the degree of attenuated mitochondrial respiratory capacity postexercise was not different between CTRL and FENT, respectively, as assessed by maximal respiratory flux through complex I (-15% and -33%), complex II (-36% and -23%), complex I + II (-31% and -20%), and state 3CI+CII control ratio (-24% and -39%). Although a basement effect cannot be ruled out, this failure of an augmented metabolic perturbation to extensively further attenuate mitochondrial function questions the direct role of high-intensity exercise-induced metabolite accumulation in this postexercise response.
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Affiliation(s)
- Matthew T Lewis
- Division of Geriatrics, Department of Medicine, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Gregory M Blain
- LAMHESS, University Nice Sophia Antipolis, Nice, France.,LAMHESS, University of Toulon, La Garde, France
| | - Corey R Hart
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - Gwenael Layec
- Division of Geriatrics, Department of Medicine, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah
| | - Matthew J Rossman
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - Song-Young Park
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah.,School of Health and Kinesiology, University of Nebraska, Omaha, Nebraska
| | - Joel D Trinity
- Division of Geriatrics, Department of Medicine, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Jayson R Gifford
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - Simranjit K Sidhu
- Division of Geriatrics, Department of Medicine, University of Utah, Salt Lake City, Utah.,Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, South Australia, Australia
| | - Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah
| | - Thomas J Hureau
- Division of Geriatrics, Department of Medicine, University of Utah, Salt Lake City, Utah.,LAMHESS, University Nice Sophia Antipolis, Nice, France.,LAMHESS, University of Toulon, La Garde, France
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah
| | - Markus Amann
- Division of Geriatrics, Department of Medicine, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah.,Department of Anesthesiology, University of Utah, Salt Lake City, Utah
| | - Russell S Richardson
- Division of Geriatrics, Department of Medicine, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Veterans Affairs Medical Center, Salt Lake City, Utah.,Department of Exercise and Sport Science, University of Utah, Salt Lake City, Utah.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
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15
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Goulding RP, Rossiter HB, Marwood S, Ferguson C. Bioenergetic Mechanisms Linking V˙O2 Kinetics and Exercise Tolerance. Exerc Sport Sci Rev 2021; 49:274-283. [PMID: 34547760 PMCID: PMC8528340 DOI: 10.1249/jes.0000000000000267] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
We hypothesize that the V˙O2 time constant (τV˙O2) determines exercise tolerance by defining the power output associated with a "critical threshold" of intramuscular metabolite accumulation (e.g., inorganic phosphate), above which muscle fatigue and work inefficiency are apparent. Thereafter, the V˙O2 "slow component" and its consequences (increased pulmonary, circulatory, and neuromuscular demands) determine performance limits.
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Affiliation(s)
- Richie P. Goulding
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
- Laboratory for Myology, Vrije Universiteit, Amsterdam, The Netherlands
| | - Harry B. Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance CA, 90254, USA
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, L16 9JD, UK
| | - Carrie Ferguson
- School of Biomedical Sciences, Faculty of Biological Sciences & Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, LS 2 9JT, UK
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16
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Ducrocq GP, Hureau TJ, Bøgseth T, Meste O, Blain GM. Recovery from Fatigue after Cycling Time Trials in Elite Endurance Athletes. Med Sci Sports Exerc 2021; 53:904-917. [PMID: 33148973 DOI: 10.1249/mss.0000000000002557] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
INTRODUCTION We determined the recovery from neuromuscular fatigue in six professional (PRO) and seven moderately trained (MOD) cyclists after repeated cycling time trials of various intensities/durations. METHOD Participants performed two 1-min (1minTT) or two 10-min (10minTT) self-paced cycling time trials with 5 min of recovery in between. Central and peripheral fatigue were quantified via preexercise to postexercise (15-s through 15-min recovery) changes in voluntary activation (VA) and potentiated twitch force. VA was measured using the interpolated twitch technique, and potentiated twitch force was evoked by single (QTsingle) and paired (10-Hz (QT10) and 100-Hz (QT100)) electrical stimulations of the femoral nerve. RESULTS Mean power output was 32%-72% higher during all the time trials and decreased less (-10% vs -13%) from the first to second time trial in PRO compared with MOD (P < 0.05). Conversely, exercise-induced reduction in QTsingle and QT10/QT100 was significantly lower in PRO after every time trial (P < 0.05). Recovery from fatigue from 15 s to 2 min for QTsingle and QT10/QT100 was slower in PRO after every time trial (P < 0.05). In both groups, the reduction in QTsingle was lower after the 10minTTs compared with 1minTTs (P < 0.05). Conversely, VA decreased more after the 10minTTs compared with 1minTTs (P < 0.05). CONCLUSION Our findings showed that excitation-contraction coupling was preserved after exercise in PRO compared with MOD. This likely contributed to the improved performance during repeated cycling time trials of various intensity/duration in PRO, despite a slower rate of recovery in its early phase. Finally, the time course of recovery from neuromuscular fatigue in PRO was dependent on the effects of prolonged low-frequency force depression.
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17
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Bonilla DA, Kreider RB, Stout JR, Forero DA, Kerksick CM, Roberts MD, Rawson ES. Metabolic Basis of Creatine in Health and Disease: A Bioinformatics-Assisted Review. Nutrients 2021; 13:nu13041238. [PMID: 33918657 PMCID: PMC8070484 DOI: 10.3390/nu13041238] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2021] [Revised: 04/01/2021] [Accepted: 04/07/2021] [Indexed: 02/06/2023] Open
Abstract
Creatine (Cr) is a ubiquitous molecule that is synthesized mainly in the liver, kidneys, and pancreas. Most of the Cr pool is found in tissues with high-energy demands. Cr enters target cells through a specific symporter called Na+/Cl−-dependent Cr transporter (CRT). Once within cells, creatine kinase (CK) catalyzes the reversible transphosphorylation reaction between [Mg2+:ATP4−]2− and Cr to produce phosphocreatine (PCr) and [Mg2+:ADP3−]−. We aimed to perform a comprehensive and bioinformatics-assisted review of the most recent research findings regarding Cr metabolism. Specifically, several public databases, repositories, and bioinformatics tools were utilized for this endeavor. Topics of biological complexity ranging from structural biology to cellular dynamics were addressed herein. In this sense, we sought to address certain pre-specified questions including: (i) What happens when creatine is transported into cells? (ii) How is the CK/PCr system involved in cellular bioenergetics? (iii) How is the CK/PCr system compartmentalized throughout the cell? (iv) What is the role of creatine amongst different tissues? and (v) What is the basis of creatine transport? Under the cellular allostasis paradigm, the CK/PCr system is physiologically essential for life (cell survival, growth, proliferation, differentiation, and migration/motility) by providing an evolutionary advantage for rapid, local, and temporal support of energy- and mechanical-dependent processes. Thus, we suggest the CK/PCr system acts as a dynamic biosensor based on chemo-mechanical energy transduction, which might explain why dysregulation in Cr metabolism contributes to a wide range of diseases besides the mitigating effect that Cr supplementation may have in some of these disease states.
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Affiliation(s)
- Diego A. Bonilla
- Research Division, Dynamical Business & Science Society–DBSS International SAS, Bogotá 110861, Colombia
- Research Group in Biochemistry and Molecular Biology, Universidad Distrital Francisco José de Caldas, Bogotá 110311, Colombia
- Research Group in Physical Activity, Sports and Health Sciences (GICAFS), Universidad de Córdoba, Montería 230002, Colombia
- kDNA Genomics, Joxe Mari Korta Research Center, University of the Basque Country UPV/EHU, 20018 Donostia-San Sebastián, Spain
- Correspondence: ; Tel.: +57-320-335-2050
| | - Richard B. Kreider
- Exercise & Sport Nutrition Laboratory, Human Clinical Research Facility, Texas A&M University, College Station, TX 77843, USA;
| | - Jeffrey R. Stout
- Physiology of Work and Exercise Response (POWER) Laboratory, Institute of Exercise Physiology and Rehabilitation Science, University of Central Florida, Orlando, FL 32816, USA;
| | - Diego A. Forero
- Professional Program in Sport Training, School of Health and Sport Sciences, Fundación Universitaria del Área Andina, Bogotá 111221, Colombia;
| | - Chad M. Kerksick
- Exercise and Performance Nutrition Laboratory, School of Health Sciences, Lindenwood University, Saint Charles, MO 63301, USA;
| | - Michael D. Roberts
- School of Kinesiology, Auburn University, Auburn, AL 36849, USA;
- Edward via College of Osteopathic Medicine, Auburn, AL 36849, USA
| | - Eric S. Rawson
- Department of Health, Nutrition and Exercise Science, Messiah University, Mechanicsburg, PA 17055, USA;
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18
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Garnacho-Castaño MV, Albesa-Albiol L, Serra-Payá N, Gomis Bataller M, Pleguezuelos Cobo E, Guirao Cano L, Guodemar-Pérez J, Carbonell T, Domínguez R, Maté-Muñoz JL. Oxygen Uptake Slow Component and the Efficiency of Resistance Exercises. J Strength Cond Res 2021; 35:1014-1022. [PMID: 30335719 DOI: 10.1519/jsc.0000000000002905] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
ABSTRACT Garnacho-Castaño, MV, Albesa-Albiol, L, Serra-Payá, N, Gomis Bataller, M, Pleguezuelos Cobo, E, Guirao Cano, L, Guodemar-Pérez, J, Carbonell, T, Domínguez, R, and Maté-Muñoz, JL. Oxygen uptake slow component and the efficiency of resistance exercises. J Strength Cond Res 35(4): 1014-1022, 2021-This study aimed to evaluate oxygen uptake slow component (V̇o2sc) and mechanical economy/efficiency in half squat (HS) exercise during constant-load tests conducted at lactate threshold (LT) intensity. Nineteen healthy young men completed 3 HS exercise tests separated by 48-hour rest periods: 1 repetition maximum (1RM), incremental-load HS test to establish the %1RM corresponding to the LT, and constant-load HS test at the LT. During the last test, cardiorespiratory, lactate, and mechanical responses were monitored. Fatigue in the lower limbs was assessed before and after the constant-load test using a countermovement jump test. A slight and sustained increase of the V̇o2sc and energy expended (EE) was observed (p < 0.001). In blood lactate, no differences were observed between set 3 to set 21 (p > 0.05). A slight and sustained decrease of half squat efficiency and gross mechanical efficiency (GME) was detected (p < 0.001). Significant inverse correlations were observed between V̇o2 and GME (r = -0.93, p < 0.001). Inverse correlations were detected between EE and GME (r = -0.94, p < 0.001). Significant losses were observed in jump height ability and in mean power output (p < 0.001) in response to the constant-load HS test. In conclusion, V̇o2sc and EE tended to rise slowly during constant-load HS exercise testing. This slight increase was associated with lowered efficiency throughout constant-load test and a decrease in jump capacity after testing. These findings would allow to elucidate the underlying fatigue mechanisms produced by resistance exercises in a constant-load test at LT intensity.
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Affiliation(s)
- Manuel V Garnacho-Castaño
- GRI-AFIRS, Department of Physical Activity and Sports Science, School of Health Sciences, TecnoCampus, Pompeu Fabra University, Barcelona, Spain
| | - Lluis Albesa-Albiol
- GRI-AFIRS, Department of Physical Activity and Sports Science, School of Health Sciences, TecnoCampus, Pompeu Fabra University, Barcelona, Spain
| | - Noemí Serra-Payá
- GRI-AFIRS, Department of Physical Activity and Sports Science, School of Health Sciences, TecnoCampus, Pompeu Fabra University, Barcelona, Spain
| | - Manuel Gomis Bataller
- GRI-AFIRS, Department of Physical Activity and Sports Science, School of Health Sciences, TecnoCampus, Pompeu Fabra University, Barcelona, Spain
| | - Eulogio Pleguezuelos Cobo
- GRI-AFIRS, Department of Physical Activity and Sports Science, School of Health Sciences, TecnoCampus, Pompeu Fabra University, Barcelona, Spain
- Department of Physical and Rehabilitation Medicine, Mataró Hospital, Barcelona, Spain
| | - Lluis Guirao Cano
- GRI-AFIRS, Department of Physical Activity and Sports Science, School of Health Sciences, TecnoCampus, Pompeu Fabra University, Barcelona, Spain
- Department of Physical and Rehabilitation Medicine, Mataró Hospital, Barcelona, Spain
| | | | - Teresa Carbonell
- Department of Physiology, University of Barcelona, Barcelona, Spain ; and
| | - Raúl Domínguez
- Department of Physical Activity and Sports Science, Alfonso X El Sabio University, Madrid, Spain
| | - José Luis Maté-Muñoz
- Department of Physical Activity and Sports Science, Alfonso X El Sabio University, Madrid, Spain
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19
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Robergs RA. Quantifying H + exchange from muscle cytosolic energy catabolism using metabolite flux and H + coefficients from multiple competitive cation binding: New evidence for consideration in established theories. Physiol Rep 2021; 9:e14728. [PMID: 33904663 PMCID: PMC8077081 DOI: 10.14814/phy2.14728] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Revised: 10/18/2020] [Accepted: 01/03/2021] [Indexed: 11/30/2022] Open
Abstract
The purpose of this investigation was to present calculations of fractional H+ exchange (~H+e ) from the chemical reactions of non-mitochondrial energy catabolism. Data of muscle pH and metabolite accumulation were based on published research for intense exercise to contractile failure within ~3 min, from which capacities and time profiles were modeled. Data were obtained from prior research for multiple competitive cation dissociation constants of metabolites and the chemical reactions of non-mitochondrial energy catabolism, and pH dependent calculations of ~H+e from specific chemical reactions. Data revealed that the 3 min of intense exercise incurred a total ATP turnover of 142.5 mmol L-1 , with a total intramuscular ~H+ exchange (-'ve = release) of -187.9 mmol L-1 . Total ~H+ metabolic consumption was 130.6 mmol L-1 , revealing a net total ~H+e (~H+te ) of -57.3 mmol L-1 . Lactate production had a ~H+te of 44.2 mmol L-1 (for a peak accumulation = 45 mmol L-1 ). The net ~H+te for the sum of the CK, AK, and AMPD reactions was 36.33 mmol L-1 . The ~H+te from ATP turnover equaled -47.5 mmol L-1 . The total ~H+ release to lactate ratio was 4.3 (187.9/44). Muscle ~H+ release during intense exercise is up to ~4-fold larger than previously assumed based on the lactic acid construct.
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Affiliation(s)
- Robert A. Robergs
- School of Exercise and Nutrition SciencesFaculty of HealthQueensland University of TechnologyKelvin GroveQLDAustralia
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20
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Bartlett MF, Fitzgerald LF, Kent JA. Rates of oxidative ATP synthesis are not augmented beyond the pH threshold in human vastus lateralis muscles during a stepwise contraction protocol. J Physiol 2021; 599:1997-2013. [PMID: 33576028 DOI: 10.1113/jp280851] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 02/05/2021] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The oxygen cost of high-intensity exercise at power outputs above an individual's lactate threshold (LT) is greater than would be predicted by the linear oxygen consumption-power relationship observed below the LT. However, whether these augmentations are caused by an increased ATP cost of force generation (ATPCOST ) or an increased oxygen cost of ATP synthesis is unclear. We used 31 P-MRS to measure changes in cytosolic [ADP] (intramyocellular marker of oxidative metabolism), oxidative ATP synthesis (ATPOX ) and ATPCOST during a 6-stage, stepwise knee extension protocol. ATPCOST was unchanged across stages. The relationship between [ADP] and muscle power output was augmented at workloads above the pH threshold (pHT ; proxy for LT), whereas increases in ATPOX were attenuated. These results suggest the greater oxygen cost of contractions at workloads beyond the pHT is not caused by mechanisms that increase ATPCOST , but rather mechanisms that alter intrinsic mitochondrial function or capacity. ABSTRACT Increases in skeletal muscle metabolism and oxygen consumption are linearly related to muscle power output for workloads below the lactate threshold (LT), but are augmented (i.e. greater rate of increase relative to workload) thereafter. Presently, it is unclear whether these metabolic augmentations are caused by increases in the ATP cost of force generation (ATPCOST ) or changes in the efficiency of mitochondrial oxygen consumption and oxidative ATP synthesis (ATPOX ). To partition these two hypotheses in vivo, we used 31 P-MRS to calculate slopes relating step-changes in muscle work to concurrent changes in cytosolic phosphates and ATPOX before and after the pH threshold (pHT ; used here as a proxy for LT) within the vastus lateralis muscle of eight young adults during a stepwise knee extension test. Changes in muscle phosphates and ATPOX were linearly related to workload below the pHT . However, slopes above the pHT were greater for muscle phosphates (P < 0.05) and lower for ATPOX (P < 0.05) than were the slopes observed below the pHT . The maximal capacity for ATPOX ( V ̇ max ) and ADP-specific ATPOX also declined beyond the pHT (P < 0.05), whereas ATPCOST was unchanged (P = 0.10). These results oppose the hypothesis that high-intensity contractions increase ATPCOST and suggest that greater oxidative metabolism at workloads beyond the pHT is caused by mechanisms that affect intrinsic mitochondrial function or capacity, such as alterations in substrate selection or electron entry into the electron transport chain, temperature-mediated changes in mitochondrial permeability to protons, or stimulation of mitochondrial uncoupling by reactive oxygen species generation.
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Affiliation(s)
- Miles F Bartlett
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Liam F Fitzgerald
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA, 01003, USA
| | - Jane A Kent
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA, 01003, USA
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21
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Kaviani M, Izadi A, Heshmati J. Would creatine supplementation augment exercise performance during a low carbohydrate high fat diet? Med Hypotheses 2020; 146:110369. [PMID: 33214000 DOI: 10.1016/j.mehy.2020.110369] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 10/06/2020] [Accepted: 10/26/2020] [Indexed: 02/07/2023]
Abstract
Low carbohydrate high fat (LCHF) diets are emerging in popularity. Several athletics have adopted LCHF diets in an attempt to improve exercise performance and body composition by enhancing fat utilization. However, these diets impair maximal and supramaximal exercise performance due to limited glycogen stores as well as increasing ratings of perceived exertion (RPE). All of these factors may impact training volume and compliance, leading to less optimal training adaptations over time. In contrast, LCHF diets is an effective strategy for weight and fat mass loss and is beneficial for a variety of metabolic processes. One potential nutritional strategy to off-set the negative aspects of a LCHF is creatine (Cr). Creatine supplementation has been shown to increase muscle power output and reduce the rate of fatigue; thereby allowing individuals to work at a higher intensity for a greater duration. Furthermore, Cr supplementation may positively enhance body composition (gains in muscle mass and possibly aid in fat mass loss). Despite the popularity of both LCHF and creatine supplementation, there is no data available investigating the effects of Cr supplementation on exercise performance and body composition during LCHF diets in humans. We would hypothesize that Cr supplementation may augment exercise performance (anerobic power and strength) during a LCHF diet compared to a LCHF diet and placebo. In addition, combining Cr with a LCHF diet would further increase body fat loss and improve body composition compared to a LCHF diet and/or low-fat diets (LFDs) placebo. Our hypotheses would be under the assumption that total caloric intake and protein intake are matched. Future research is warranted to examine chronic exercise with LCHF diets with and without creatine and compare performance and body composition changes to high carbohydrate diets.
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Affiliation(s)
- Mojtaba Kaviani
- School of Nutrition and Dietetics, Faculty of Pure and Applied Science, Acadia University, Wolfville, Nova Scotia B4P 2R6, Canada.
| | - Azimeh Izadi
- Department of Biochemistry and Diet Therapy, Faculty of Nutrition and Food Sciences, Tabriz University of Medical Sciences, Tabriz, Iran.
| | - Javad Heshmati
- Department of Nutritional Science, School of Nutritional Science and Food Technology, Kermanshah University of Medical Sciences, Kermanshah, Iran
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Bartlett MF, Fitzgerald LF, Nagarajan R, Kent JA. Validity and accuracy of calculating oxidative ATP synthesis in vivo during high-intensity skeletal muscle contractions. NMR IN BIOMEDICINE 2020; 33:e4381. [PMID: 32803787 DOI: 10.1002/nbm.4381] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/27/2020] [Accepted: 07/02/2020] [Indexed: 06/11/2023]
Abstract
Several methods have been developed for using 31 P-MRS to calculate rates of oxidative ATP synthesis (ATPOX ) during muscular contractions based on assumptions that (1) the ATP cost of force generation (ATPCOST ) remains constant or (2) Michaelis-Menten coupling between cytosolic ADP and ATPOX does not change. However, growing evidence suggests that one, or both, of these assumptions are invalid during high-intensity fatigue protocols. Consequently, there is a need to examine the validity and accuracy of traditional ATPOX calculation methods under these conditions. To address this gap, we measured phosphate concentrations and pH in the vastus lateralis muscle of nine young adults during four rest-contraction-recovery trials lasting 24, 60, 120, and 240 s. The initial velocity of phosphocreatine resynthesis (ViPCr ) following each trial served as the criterion measure of ATPOX because this method makes no assumptions of constant ATPCOST or Michaelis-Menten coupling between changes in cytosolic ADP and ATPOX . Subsequently, we calculated ATPOX throughout the 240 s trial using several traditional calculation methods and compared estimations of ATPOX from each method with time-matched measurements of ViPCr . Method 1, which assumes that ATPCOST does not change, was able to model changes in ViPCr over time, but showed poor accuracy for predicting ViPCr across a wide range of ATPOX values. In contrast, Michaelis-Menten methods, which assume that the relationship between changes in cytosolic ADP and ATPOX remains constant, were invalid because they could not model the decline in ViPCr . However, adjusting these Michaelis-Menten methods for observed changes in maximal ATPOX capacity (i.e., Vmax ) permitted modeling of the decline in ViPCr and markedly improved accuracy. The results of these comprehensive analyses demonstrate that valid, accurate measurements of ATPOX can be obtained during high-intensity contractions by adjusting Michaelis-Menten ATPOX calculations for changes in Vmax observed from baseline to post-fatigue.
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Affiliation(s)
- Miles F Bartlett
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Liam F Fitzgerald
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Rajakumar Nagarajan
- Human Magnetic Resonance Center, Institute for Applied Life Sciences (IALS), University of Massachusetts Amherst, Amherst, Massachusetts, USA
| | - Jane A Kent
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts Amherst, Amherst, Massachusetts, USA
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23
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Santos PS, Felippe LC, Ferreira GA, Learsi SK, Couto PG, Bertuzzi R, Pereira G, Lima-Silva AE. Caffeine increases peripheral fatigue in low- but not in high-performing cyclists. Appl Physiol Nutr Metab 2020; 45:1208-1215. [DOI: 10.1139/apnm-2019-0992] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The influence of cyclists’ performance levels on caffeine-induced increases in neuromuscular fatigue after a 4-km cycling time trial (TT) was investigated. Nineteen cyclists performed a 4-km cycling TT 1 h after ingesting caffeine (5 mg·kg−1) or placebo (cellulose). Changes from baseline to after exercise in voluntary activation (VA) and potentiated 1 Hz force twitch (Qtw,pot) were used as markers of central and peripheral fatigue, respectively. Participants were classified as “high performing” (HP, n = 8) or “low performing” (LP, n = 8) in accordance with their performance in a placebo trial. Compared with placebo, caffeine increased the power, anaerobic mechanical power, and anaerobic work, reducing the time to complete the trial in both groups (p < 0.05). There was a group versus supplement and a group versus supplement versus trial interaction for Qtw,pot, in which the postexercise reduction was greater after caffeine compared with placebo in the LP group (Qtw,pot = −34% ± 17% vs. −21% ± 11%, p = 0.02) but not in the HP group (Qtw,pot = −22% ± 8% vs. −23% ± 10%, p = 0.64). There was no effect of caffeine on VA, but there was a group versus trial interaction with lower postexercise values in the LP group than in the HP group (p = 0.03). Caffeine-induced improvement in 4-km cycling TT performance seems to come at the expense of greater locomotor muscle fatigue in LP but not in HP cyclists. Novelty Caffeine improves exercise performance at the expense of a greater end-exercise peripheral fatigue in low-performing athletes. Caffeine-induced improvement in exercise performance does not affect end-exercise peripheral fatigue in high-performing athletes. High-performing athletes seem to have augmented tolerance to central fatigue during a high-intensity time trial.
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Affiliation(s)
- Pamela S. Santos
- Human Performance Research Group, Academic Department of Physical Education, Federal University of Technology – Parana (UTFPR), Neoville, Curitiba, PR 81310-900, Brazil
- Department of Physical Education, Federal University of Parana, Curitiba, PR 81531-980, Brazil
| | - Leandro C. Felippe
- Human Performance Research Group, Academic Department of Physical Education, Federal University of Technology – Parana (UTFPR), Neoville, Curitiba, PR 81310-900, Brazil
- Sport Science Research Group, Federal University of Pernambuco, Vitoria de Santo Antao, PE 55608-608, Brazil
| | - Guilherme A. Ferreira
- Human Performance Research Group, Academic Department of Physical Education, Federal University of Technology – Parana (UTFPR), Neoville, Curitiba, PR 81310-900, Brazil
- Sport Science Research Group, Federal University of Pernambuco, Vitoria de Santo Antao, PE 55608-608, Brazil
| | - Sara K. Learsi
- Human Performance Research Group, Academic Department of Physical Education, Federal University of Technology – Parana (UTFPR), Neoville, Curitiba, PR 81310-900, Brazil
- Sport Science Research Group, Federal University of Pernambuco, Vitoria de Santo Antao, PE 55608-608, Brazil
| | - Patrícia G. Couto
- Endurance Sports Research Group (GEDAE-USP), University of São Paulo, São Paulo, SP 05508-030, Brazil
| | - Romulo Bertuzzi
- Endurance Sports Research Group (GEDAE-USP), University of São Paulo, São Paulo, SP 05508-030, Brazil
| | - Gleber Pereira
- Department of Physical Education, Federal University of Parana, Curitiba, PR 81531-980, Brazil
| | - Adriano E. Lima-Silva
- Human Performance Research Group, Academic Department of Physical Education, Federal University of Technology – Parana (UTFPR), Neoville, Curitiba, PR 81310-900, Brazil
- Sport Science Research Group, Federal University of Pernambuco, Vitoria de Santo Antao, PE 55608-608, Brazil
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Abdalla LHP, Broxterman RM, Greco CC, Denadai BS. Creatine supplementation attenuates the rate of fatigue development during intermittent isometric exercise performed above end-test torque. Exp Physiol 2020; 105:2073-2085. [PMID: 33073449 DOI: 10.1113/ep088910] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/12/2020] [Accepted: 09/01/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does creatine supplementation augment the total torque impulse accumulated above end-test torque (IET) during severe-intensity knee-extensor exercise by attenuating the rate of decrease in peak potentiated twitch torque (PT)? What is the main finding and its importance? Creatine augmented the IET and attenuated the rate of decrease in both voluntary activation and PT during severe-intensity exercise. The IET was related to the rate of decrease in PT. These findings reveal an important role for the rates of neuromuscular fatigue development as key determinants of exercise tolerance within the severe domain. ABSTRACT This study investigated the effect of creatine supplementation on exercise tolerance, total torque impulse accumulated above end-test torque (total IET) and neuromuscular fatigue development of the knee extensors during severe-intensity intermittent isometric exercise. Sixteen men were randomly allocated into Creatine (n = 8, 20 g day-1 for 5 days) or Placebo (n = 8) groups and performed knee-extensor maximal voluntary contraction (MVC) testing, all-out testing to determine end-test torque (ET) and the finite torque impulse accumulated above end-test torque (IET'), and three submaximal tests at ET + 10%: (i) time to task failure without supplementation (Baseline); (ii) time to task failure after creatine or placebo supplementation; and (iii) time matched to Baseline after creatine (Creatine-Isotime) or placebo (Placebo-Isotime) supplementation. Creatine supplementation significantly increased the time to task failure (Baseline = 572 ± 144 s versus Creatine = 833 ± 221 s) and total IET (Baseline = 5761 ± 1710 N m s versus Creatine = 7878 ± 1903 N m s), but there were no significant differences within the Placebo group. The percentage change pre- to postexercise in MVC, voluntary activation, peak potentiated twitch torque and integrated EMG during MVC were not significantly different between Baseline and Creatine but were all significantly attenuated in Creatine-Isotime compared with Baseline. There were no significant differences in these variables within the placebo group. The total IET was significantly correlated with the rates of change in potentiated twitch torque peak (r = 0.83-0.87) and rate of torque development (r = -0.83 to -0.87) for the submaximal tests to task failure. These findings reveal an important role for the rates of neuromuscular fatigue development as key determinants of exercise tolerance during severe-intensity intermittent isometric exercise.
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Affiliation(s)
| | - Ryan Michael Broxterman
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education and Clinical Center, VA Medical Center, Salt Lake City, UT, USA
| | - Camila Coelho Greco
- Human Performance Laboratory, São Paulo State University, Rio Claro, SP, Brazil
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25
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Zarzissi S, Bouzid MA, Zghal F, Rebai H, Hureau TJ. Aging reduces the maximal level of peripheral fatigue tolerable and impairs exercise capacity. Am J Physiol Regul Integr Comp Physiol 2020; 319:R617-R625. [PMID: 32966120 DOI: 10.1152/ajpregu.00151.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The aim of the present study was to determine the magnitude of the maximal level of peripheral fatigue attainable (fatigue threshold) during an all-out intermittent isometric knee-extensor protocol in both younger (24 ± 1 yr, n = 12) and older (60 ± 2 yr, n = 12) participants to provide new insights into the effects of aging on neuromuscular function. Participants performed two experimental sessions, in which they performed 60 maximal voluntary contractions (MVCs; 3 s of contraction, 2 s of relaxation). One trial was performed in the unfatigued state (CTRL) and one other following fatiguing neuromuscular electrical stimulation of the quadriceps (FNMES). Peripheral fatigue was quantified via pre/postexercise decrease in quadriceps twitch force (∆Ptw). Critical force (CF) was determined as the mean force output of the last 12 contractions, whereas W' was calculated as the area above CF. Although FNMES led to a significant decrease in Ptw before performing the 60-MVCs protocol (P = 0.024), ∆Ptw was not different between CTRL and FNMES for both the young group (P = 0.491) and the old group (P = 0.523). However, this peripheral fatigue threshold was significantly greater in young versus old participants (∆Ptw = -48 ± 10% vs. -29 ± 13%, respectively, P = 0.028). In CTRL, W' was 55 ± 13% lower in the old group than in the young group (P < 0.001), but CF was similar (326 ± 10 N vs. 322 ± 12 N, respectively, P = 0.941). ∆Ptw was correlated with W', independently of age (r2 = 0.84, P < 0.001). Exercise performance decreases with aging consequent to a lower tolerance to peripheral fatigue. However, the peripheral fatigue threshold mechanism persists with healthy aging and continues to play a protective role in preserving locomotor muscle function during exercise.
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Affiliation(s)
- Slim Zarzissi
- Education, Motor Skills, Sport and Health Laboratory, High Institute of Sport and Physical Education, University of Sfax, Sfax, Tunisia
| | - Mohamed Amine Bouzid
- Education, Motor Skills, Sport and Health Laboratory, High Institute of Sport and Physical Education, University of Sfax, Sfax, Tunisia
| | - Firas Zghal
- Education, Motor Skills, Sport and Health Laboratory, High Institute of Sport and Physical Education, University of Sfax, Sfax, Tunisia
| | - Haithem Rebai
- Education, Motor Skills, Sport and Health Laboratory, High Institute of Sport and Physical Education, University of Sfax, Sfax, Tunisia
| | - Thomas J Hureau
- Mitochondria, Oxidative Stress and Muscular Protection Laboratory (UR 3072), Faculty of Medicine, University of Strasbourg, Strasbourg, France.,European Centre for Education, Research and Innovation in Exercise Physiology (CEERIPE), Faculty of Sport Sciences, University of Strasbourg, Strasbourg, France
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26
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Hammer SM, Alexander AM, Didier KD, Barstow TJ. Influence of blood flow occlusion on muscular recruitment and fatigue during maximal‐effort small muscle‐mass exercise. J Physiol 2020; 598:4293-4306. [DOI: 10.1113/jp279925] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/22/2020] [Indexed: 11/08/2022] Open
Affiliation(s)
- Shane M. Hammer
- Department of Kinesiology Kansas State University Manhattan KS USA
| | | | - Kaylin D. Didier
- Department of Kinesiology Kansas State University Manhattan KS USA
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Alexander AM, Didier KD, Hammer SM, Dzewaltowski AC, Kriss KN, Lovoy GM, Hammer JL, Smith JR, Ade CJ, Broxterman RM, Barstow TJ. Exercise tolerance through severe and extreme intensity domains. Physiol Rep 2020; 7:e14014. [PMID: 30825269 PMCID: PMC6397101 DOI: 10.14814/phy2.14014] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 02/01/2019] [Indexed: 01/24/2023] Open
Abstract
The power‐duration relationship accurately predicts exercise tolerance for constant power exercise performed in the severe intensity domain. However, the accuracy of the prediction of time to task failure (Tlim) is currently unclear for work rates (WR) above severe intensities; that is, within the extreme intensity domain (Tlim < 2 min). We hypothesized that Tlim would be shorter for WRs within the extreme intensity domain than predicted from the linear 1/time relationship of the severe intensity domain which would suggest mechanisms limiting exercise are different between intensity domains. Six men completed 7 knee‐extension tests. Tlim of extreme intensity exercise (60%, 70%, 80%, and 90% 1RM; Tlim < 2 min) were compared to the predicted Tlim from the slope of the S1–S3 (Tlim ≥ 2–15 min) regression. Twitch force (Qtw) and maximal voluntary contraction (MVC) were measured on the right vastus lateralis before and after each test. Tlim at 70–90% 1RM were shorter than the Tlim predicted by the severe domain 1/time model (P < 0.05); however, Tlim at 60% 1RM was not different than the predicted severe Tlim, suggesting the mechanisms limiting extreme exercise manifest ≥60% 1RM. A significant linear relationship for 60–90% 1RM was observed which suggested a curvature constant unique to the extreme domain (Wext′) that was smaller than the W ′ of the severe domain (1.5 ± 0.6 vs. 5.9 ± 1.5 kJ, P < 0.001). Qtw and MVC were significantly decreased following severe exercise, however, Qtw and MVC were not significantly decreased following 80% and 90% 1RM, giving evidence that mechanisms causing task failure were recovered by the time post‐exercise measurements were made (~90 sec).
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Affiliation(s)
| | - Kaylin D Didier
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Shane M Hammer
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | | | - Karly N Kriss
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Garrett M Lovoy
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Joseph L Hammer
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Joshua R Smith
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Carl J Ade
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Ryan M Broxterman
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Thomas J Barstow
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
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28
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Bartlett MF, Fitzgerald LF, Nagarajan R, Hiroi Y, Kent JA. Oxidative ATP synthesis in human quadriceps declines during 4 minutes of maximal contractions. J Physiol 2020; 598:1847-1863. [PMID: 32045011 DOI: 10.1113/jp279339] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Accepted: 01/30/2020] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS During maximal exercise, skeletal muscle metabolism and oxygen consumption remain elevated despite precipitous declines in power. Presently, it is unclear whether these responses are caused by an increased ATP cost of force generation (ATPCOST ) or mitochondrial uncoupling; a process that reduces the efficiency of oxidative ATP synthesis (ATPOX ). To address this gap, we used 31-phosphorus magnetic resonance spectroscopy to measure changes in ATPCOST and ATPOX in human quadriceps during repeated trials of maximal intensity knee extensions lasting up to 4 min. ATPCOST remained unchanged. In contrast, ATPOX plateaued by ∼2 min and then declined (∼15%) over the final 2 min. The maximal capacity for ATPOX (Vmax ), as well as ADP-specific rates of ATPOX , were also significantly diminished. Collectively, these results suggest that mitochondrial uncoupling, and not increased ATPCOST , is responsible for altering the regulation of skeletal muscle metabolism and oxygen consumption during maximal exercise. ABSTRACT The relationship between skeletal muscle oxygen consumption and power output is augmented during exercise at workloads above the lactate threshold. Potential mechanisms for this response have been hypothesized, including increased ATP cost of force generation (ATPCOST ) and mitochondrial uncoupling, a process that reduces the efficiency of oxidative ATP synthesis (ATPOX ). To test these hypotheses, we used phosphorus magnetic resonance spectroscopy to non-invasively measure changes in phosphate concentrations and pH in the vastus lateralis muscle of nine young adults during repeated trials of maximal, all-out dynamic knee extensions (120°s-1 , 1 every 2 s) lasting 24, 60, 120, and 240 s. ATPOX was measured at each time point from the initial velocity of PCr resynthesis, and ATPCOST was calculated as the sum of ATP synthesized by the creatine and adenylate kinase reactions, non-oxidative glycolysis, ATPOX and net changes in [ATP]. Power output declined in a reproducible manner for all four trials. ATPCOST did not change over time (main effect P = 0.45). ATPOX plateaued from 60 to 120 s and then decreased over the final 120 s (main effect P = 0.001). The maximal capacity for oxidative ATP synthesis (Vmax ), as well as ADP-specific rates of ATPOX , also decreased over time (main effect P = 0.001, both). Collectively, these results demonstrate that prolonged maximal contraction protocols impair oxidative energetics and implicate mitochondrial uncoupling as the mechanism for this response. The causes of mitochondrial uncoupling are presently unknown but may offer a potential explanation for the dissociation between skeletal muscle power output and oxygen consumption during maximal, all-out exercise protocols.
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Affiliation(s)
- Miles F Bartlett
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, 01003.,Department of Kinesiology, University of Texas, Arlington, Texas, 76019
| | - Liam F Fitzgerald
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, 01003
| | - Rajakumar Nagarajan
- Human Magnetic Resonance Center, Institute for Applied Life Sciences (IALS), University of Massachusetts, Amherst, Massachusetts, 01003
| | - Yeun Hiroi
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, 01003
| | - Jane A Kent
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, 01003
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29
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Limb blood flow and muscle oxygenation responses during handgrip exercise above vs. below critical force. Microvasc Res 2020; 131:104002. [PMID: 32198059 DOI: 10.1016/j.mvr.2020.104002] [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: 02/12/2020] [Revised: 03/14/2020] [Accepted: 03/14/2020] [Indexed: 11/20/2022]
Abstract
This study compared the brachial artery blood flow (Q̇BA) and microvascular oxygen delivery responses during handgrip exercise above vs. below critical force (CF; the isometric analog of critical power). Q̇BA and microvascular oxygen delivery are important determinants of oxygen utilization and metabolite accumulation during exercise, both of which increase progressively during exercise above CF. However the Q̇BA and microvascular oxygen delivery responses above vs. below CF remain unknown. We hypothesized that Q̇BA, deoxygenated-heme (deoxy-[heme]; an estimate of microvascular fractional oxygen extraction), and total-heme concentrations (total-[heme]; an estimate of changes in microvascular hematocrit) would demonstrate physiological maximums above CF despite increases in exercise intensity. Seven men and six women performed 1) a 5-min rhythmic isometric-handgrip maximal-effort test (MET) to determine CF and 2) two constant target-force tests above (severe-intensity; S1 and S2) and two constant target-force tests below (heavy-intensity; H1 and H2) CF. CF was 189.3 ± 16.7 N (29.7 ± 1.6%MVC). At end-exercise, Q̇BA was greater for tests above CF (S1: 418 ± 147 mL/min; S2: 403 ± 137 mL/min) compared to tests below CF (H1: 287 ± 97 mL/min; H2: 340 ± 116 mL/min; all p < 0.05) but was not different between S1 and S2. Further, end-test Q̇BA during both tests above CF was not different from Q̇BA estimated at CF (392 ± 37 mL/min). At end-exercise, deoxy-[heme] was not different between tests above CF (S1: 150 ± 50 μM; S2: 155 ± 57 μM), but was greater during tests above CF compared to tests below CF (H1: 101 ± 24 μM; H2: 111 ± 21 μM; all p < 0.05). At end-exercise, total-[heme] was not different between tests above CF (S1: 404 ± 58 μM; S2: 397 ± 73 μM), but was greater during tests above CF compared to H1 (352 ± 58 μM; p < 0.01) but not H2 (371 ± 57 μM). These data suggest limb blood flow limitations exist and maximal levels of muscle microvascular oxygen delivery and extraction occur during exercise above, but not below, CF.
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30
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A thermodynamic function of glycogen in brain and muscle. Prog Neurobiol 2020; 189:101787. [PMID: 32151532 DOI: 10.1016/j.pneurobio.2020.101787] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/30/2020] [Accepted: 03/03/2020] [Indexed: 11/20/2022]
Abstract
Brain and muscle glycogen are generally thought to function as local glucose reserves, for use during transient mismatches between glucose supply and demand. However, quantitative measures show that glucose supply is likely never rate-limiting for energy metabolism in either brain or muscle under physiological conditions. These tissues nevertheless do utilize glycogen during increased energy demand, despite the availability of free glucose, and despite the ATP cost of cycling glucose through glycogen polymer. This seemingly wasteful process can be explained by considering the effect of glycogenolysis on the amount of energy obtained from ATP (ΔG'ATP). The amount of energy obtained from ATP is reduced by elevations in inorganic phosphate (Pi). Glycogen utilization sequesters Pi in the glycogen phosphorylase reaction and in downstream phosphorylated glycolytic intermediates, thereby buffering Pi elevations and maximizing energy yield at sites of rapid ATP consumption. This thermodynamic effect of glycogen may be particularly important in the narrow, spatially constrained astrocyte processes that ensheath neuronal synapses and in cells such as astrocytes and myocytes that release Pi from phosphocreatine during energy demand. The thermodynamic effect may also explain glycolytic super-compensation in brain when glycogen is not available, and aspects of exercise physiology in muscle glycogen phosphorylase deficiency (McArdle disease).
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31
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Ducrocq GP, Kaufman MP. Inorganic phosphate and lactate potentiate the pressor response to acidic stimuli in rats. Exp Physiol 2020; 105:613-621. [PMID: 31982004 DOI: 10.1113/ep088349] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 01/23/2020] [Indexed: 12/15/2022]
Abstract
NEW FINDINGS What is the central question of this study? What is the contribution of the main acidic compounds accumulated during contractions, namely H+ , lactic acid and inorganic phosphate, to evoke the metabolic component of the exercise pressor reflex? What is the main finding and its importance? We found that the pressor response to acidic stimuli is driven by the concentration of hydrogen ions and that lactate and inorganic phosphate act as potentiating agents. ABSTRACT H+ ions, lactate and inorganic phosphate are produced by contracting skeletal muscles and evoke, in part, the metabolic component of the exercise pressor reflex. Owing to their disparate dissociation constants (i.e. pKa ), the contribution of each acid to the muscle metaboreflex is unclear. This lack of information prompted us to determine the reflex pressor responses to injection of acidic saline, lactate (24 mm) and inorganic phosphate (86 mm) at various values of pH (from 2.66 to 7.5), alone or in combination, into the arterial supply of hindlimb skeletal muscle of decerebrate rats. In particular, we tested the hypothesis that the pressor response to an injection of a combination of lactate and phosphate at an acidic pH is greater than that evoked by injection of either phosphate or lactate alone at the same pH. We found that injection of acidic saline produced a pressor response only at a pH of 2.66 (7 ± 4 mmHg), an effect that was potentiated when the solution contained lactate (50 ± 20 mmHg). At a pH of 6.0, however, this effect was lost. At a pH of 6.0, only the injection of inorganic phosphate produced a significant pressor response (23 ± 12 mmHg). A large potentiating effect was found when lactate was added to the inorganic phosphate solution (39 ± 18 mmHg), an effect that was lost at a pH >7.0. Our findings led to the conclusion that the pressor response to injection of acidic solutions was driven by H+ ions and that inorganic phosphate and lactate functioned as sensitizing agents.
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Affiliation(s)
- Guillaume P Ducrocq
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, PA, 17033, USA
| | - Marc P Kaufman
- Heart and Vascular Institute, Penn State College of Medicine, Hershey, PA, 17033, USA
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32
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Unger M, Debold EP. Acidosis decreases the Ca 2+ sensitivity of thin filaments by preventing the first actomyosin interaction. Am J Physiol Cell Physiol 2019; 317:C714-C718. [PMID: 31339771 DOI: 10.1152/ajpcell.00196.2019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intracellular acidosis is a putative agent of skeletal muscle fatigue, in part, because it depresses the calcium (Ca2+) sensitivity of the myofilaments. However, the molecular mechanism behind this depression in Ca2+ sensitivity is unknown, providing a significant challenge to a complete understanding of the fatigue process. To elucidate this mechanism, we directly determined the effect of acidosis on the ability of a single myosin molecule to bind to a regulated actin filament in a laser trap assay. Decreasing pH from 7.4 to 6.5 significantly (P < 0.05) reduced the frequency of single actomyosin-binding events at submaximal (pCa 8-pCa 6) but not at maximal Ca2+ concentration (pCa 5-pCa 4). To delineate whether this was due to a direct effect on myosin versus an indirect effect on the regulatory proteins troponin (Tn) and tropomyosin (Tm), binding frequency was also quantified in the absence of Tn and Tm. This revealed that acidosis did not significantly alter the frequency of actomyosin binding events in the absence of regulatory proteins (1.4 ± 0.15 vs. 1.4 ± 0.15 events/s for pH 7.4 and 6.5, respectively). Acidosis also did not significantly affect the size of myosin's powerstroke or the duration of binding events in the presence of regulatory proteins, at every [Ca2+]. These data suggest acidosis impedes activation of the thin filament by competitively inhibiting Ca2+ binding to TnC. This slows the rate at which myosin initially attaches to actin; therefore, less cross bridges will be bound and generating force at any given submaximal [Ca2+]. These data provide a molecular explanation for the acidosis-induced decrease in force observed at the submaximal Ca2+ concentrations that might contribute to the loss of force during muscle fatigue.
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Affiliation(s)
- Matthew Unger
- Muscle Biophysics Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
| | - Edward P Debold
- Muscle Biophysics Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
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Craig JC, Colburn TD, Caldwell JT, Hirai DM, Tabuchi A, Baumfalk DR, Behnke BJ, Ade CJ, Musch TI, Poole DC. Central and peripheral factors mechanistically linked to exercise intolerance in heart failure with reduced ejection fraction. Am J Physiol Heart Circ Physiol 2019; 317:H434-H444. [PMID: 31225988 DOI: 10.1152/ajpheart.00164.2019] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Exercise intolerance is a primary symptom of heart failure (HF); however, the specific contribution of central and peripheral factors to this intolerance is not well described. The hyperbolic relationship between exercise intensity and time to exhaustion (speed-duration relationship) defines exercise tolerance but is underused in HF. We tested the hypotheses that critical speed (CS) would be reduced in HF, resting central functional measurements would correlate with CS, and the greatest HF-induced peripheral dysfunction would occur in more oxidative muscle. Multiple treadmill-constant speed runs to exhaustion were used to quantify CS and D' (distance coverable above CS) in healthy control (Con) and HF rats. Central function was determined via left ventricular (LV) Doppler echocardiography [fractional shortening (FS)] and a micromanometer-tipped catheter [LV end-diastolic pressure (LVEDP)]. Peripheral O2 delivery-to-utilization matching was determined via phosphorescence quenching (interstitial Po2, Po2 is) in the soleus and white gastrocnemius during electrically induced twitch contractions (1 Hz, 8V). CS was lower in HF compared with Con (37 ± 1 vs. 44 ± 1 m/min, P < 0.001), but D' was not different (77 ± 8 vs. 69 ± 13 m, P = 0.6). HF reduced FS (23 ± 2 vs. 47 ± 2%, P < 0.001) and increased LVEDP (15 ± 1 vs. 7 ± 1 mmHg, P < 0.001). CS was related to FS (r = 0.72, P = 0.045) and LVEDP (r = -0.75, P = 0.02) only in HF. HF reduced soleus Po2 is at rest and during contractions (both P < 0.01) but had no effect on white gastrocnemius Po2 is (P > 0.05). We show in HF rats that decrements in central cardiac function relate directly with impaired exercise tolerance (i.e., CS) and that this compromised exercise tolerance is likely due to reduced perfusive and diffusive O2 delivery to oxidative muscles.NEW & NOTEWORTHY We show that critical speed (CS), which defines the upper boundary of sustainable activity, can be resolved in heart failure (HF) animals and is diminished compared with controls. Central cardiac function is strongly related with CS in the HF animals, but not controls. Skeletal muscle O2 delivery-to-utilization dysfunction is evident in the more oxidative, but not glycolytic, muscles of HF rats and is explained, in part, by reduced nitric oxide bioavailability.
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Affiliation(s)
- Jesse C Craig
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Trenton D Colburn
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Jacob T Caldwell
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Daniel M Hirai
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Ayaka Tabuchi
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Dryden R Baumfalk
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Bradley J Behnke
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Carl J Ade
- Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Timothy I Musch
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - David C Poole
- Department of Kinesiology, Kansas State University, Manhattan, Kansas.,Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas
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Morgan PT, Bailey SJ, Banks RA, Fulford J, Vanhatalo A, Jones AM. Contralateral fatigue during severe-intensity single-leg exercise: influence of acute acetaminophen ingestion. Am J Physiol Regul Integr Comp Physiol 2019; 317:R346-R354. [PMID: 31141387 PMCID: PMC6732432 DOI: 10.1152/ajpregu.00084.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Exhaustive single-leg exercise has been suggested to reduce time to task failure (Tlim) during subsequent exercise in the contralateral leg by exacerbating central fatigue development. We investigated the influence of acetaminophen (ACT), an analgesic that may blunt central fatigue development, on Tlim during single-leg exercise completed with and without prior fatiguing exercise of the contralateral leg. Fourteen recreationally active men performed single-leg severe-intensity knee-extensor exercise to Tlim on the left (Leg1) and right (Leg2) legs without prior contralateral fatigue and on Leg2 immediately following Leg1 (Leg2-CONTRA). The tests were completed following ingestion of 1-g ACT or maltodextrin [placebo (PL)] capsules. Intramuscular phosphorus-containing metabolites and substrates and muscle activation were assessed using 31P-MRS and electromyography, respectively. Tlim was not different between Leg1ACT and Leg1PL conditions (402 ± 101 vs. 390 ± 106 s, P = 0.11). There was also no difference in Tlim between Leg2ACT-CONTRA and Leg2PL-CONTRA (324 ± 85 vs. 311 ± 92 s, P = 0.10), but Tlim was shorter in Leg2ACT-CONTRA and Leg2PL-CONTRA than in Leg2CON (385 ± 104 s, both P < 0.05). There were no differences in intramuscular phosphorus-containing metabolites and substrates or muscle activation between Leg1ACT and Leg1PL and between Leg2ACT-CONTRA and Leg2PL-CONTRA (all P > 0.05). These findings suggest that levels of metabolic perturbation and muscle activation at Tlim are not different during single-leg severe-intensity knee-extensor exercise completed with or without prior fatiguing exercise of the contralateral leg. Despite contralateral fatigue, ACT ingestion did not alter neuromuscular responses, muscle metabolites, or exercise performance.
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Affiliation(s)
- Paul T Morgan
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke's Campus, Exeter, United Kingdom
| | - Stephen J Bailey
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke's Campus, Exeter, United Kingdom
| | - Rhys A Banks
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke's Campus, Exeter, United Kingdom
| | - Jonathan Fulford
- Peninsula Clinical Research Facility, National Institute for Health Research, College of Medicine and Health, Exeter, United Kingdom
| | - Anni Vanhatalo
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke's Campus, Exeter, United Kingdom
| | - Andrew M Jones
- Department of Sport and Health Sciences, College of Life and Environmental Sciences, University of Exeter, St. Luke's Campus, Exeter, United Kingdom
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35
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Bassan N, Denadai BS, Lima LCR, Caritá RAC, Abdalla LHP, Greco CC. Effects of resistance training on impulse above end‐test torque and muscle fatigue. Exp Physiol 2019; 104:1115-1125. [DOI: 10.1113/ep087204] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 04/30/2019] [Indexed: 12/30/2022]
Affiliation(s)
- Natália Bassan
- Human Performance LaboratorySão Paulo State University Rio Claro SP Brazil
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36
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Sundberg CW, Fitts RH. Bioenergetic basis of skeletal muscle fatigue. CURRENT OPINION IN PHYSIOLOGY 2019; 10:118-127. [PMID: 31342000 DOI: 10.1016/j.cophys.2019.05.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Energetic demand from high-intensity exercise can easily exceed ATP synthesis rates of mitochondria leading to a reliance on anaerobic metabolism. The reliance on anaerobic metabolism results in the accumulation of intracellular metabolites, namely inorganic phosphate (Pi) and hydrogen (H+), that are closely associated with exercise-induced reductions in power. Cellular and molecular studies have revealed several steps where these metabolites impair contractile function demonstrating a causal role in fatigue. Elevated Pi or H+ directly inhibits force and power of the cross-bridge and decreases myofibrillar Ca2+ sensitivity, whereas Pi also inhibits Ca2+ release from the sarcoplasmic reticulum (SR). When both metabolites are elevated, they act synergistically to cause marked reductions in power, indicating that fatigue during high-intensity exercise has a bioenergetic basis.
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Affiliation(s)
- Christopher W Sundberg
- Department of Biological Sciences, Marquette University, Milwaukee, WI.,Department of Physical Therapy, Marquette University, Milwaukee, WI
| | - Robert H Fitts
- Department of Biological Sciences, Marquette University, Milwaukee, WI
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VO₂FITTING: A Free and Open-Source Software for Modelling Oxygen Uptake Kinetics in Swimming and other Exercise Modalities. Sports (Basel) 2019; 7:sports7020031. [PMID: 30678373 PMCID: PMC6409559 DOI: 10.3390/sports7020031] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/18/2019] [Accepted: 01/21/2019] [Indexed: 01/15/2023] Open
Abstract
The assessment of oxygen uptake (VO2) kinetics is a valuable non-invasive way to evaluate cardiorespiratory and metabolic response to exercise. The aim of the study was to develop, describe and evaluate an online VO2 fitting tool (VO2FITTING) for dynamically editing, processing, filtering and modelling VO2 responses to exercise. VO2FITTING was developed in Shiny, a web application framework for R language. Validation VO2 datasets with both noisy and non-noisy data were developed and applied to widely-used models (n = 7) for describing different intensity transitions to verify concurrent validity. Subsequently, we then conducted an experiment with age-group swimmers as an example, illustrating how VO2FITTING can be used to model VO2 kinetics. Perfect fits were observed, and parameter estimates perfectly matched the known inputted values for all available models (standard error = 0; p < 0.001). The VO2FITTING is a valid, free and open-source software for characterizing VO2 kinetics in exercise, which was developed to help the research and performance analysis communities.
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38
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Senefeld JW, Limberg JK, Lukaszewicz KM, Hunter SK. Exercise-induced hyperemia is associated with knee extensor fatigability in adults with type 2 diabetes. J Appl Physiol (1985) 2019; 126:658-667. [PMID: 30605399 DOI: 10.1152/japplphysiol.00854.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The aim of this study was to compare fatigability, contractile function, and blood flow to the knee extensor muscles after dynamic exercise in patients with type 2 diabetes mellitus (T2DM) and controls. The hypotheses were that patients with T2DM would demonstrate greater fatigability than controls, and greater fatigability would be associated with a lower exercise-induced increase in blood flow and greater impairments in contractile function. Patients with T2DM ( n = 15; 8 men; 62.4 ± 9.0 yr; 30.4 ± 7.7 kg/m2; 7,144 ± 3,294 steps/day) and 15 healthy control subjects (8 men, 58.4 ± 6.9 yr; 28.4 ± 4.6 kg/m2; 7,893 ± 2,323 steps/day) were matched for age, sex, body mass index, and physical activity. Fatigability was quantified as the reduction in knee extensor power during a 6-min dynamic exercise. Before and after exercise, vascular ultrasonography and electrical stimulation were used to assess skeletal muscle blood flow and contractile properties, respectively. Patients with T2DM had greater fatigability (30.0 ± 20.1% vs. 14.6 ± 19.0%, P < 0.001) and lower exercise-induced hyperemia (177 ± 90% vs. 194 ± 79%, P = 0.04) than controls but similar reductions in the electrically evoked twitch amplitude (37.6 ± 24.8% vs. 31.6 ± 30.1%, P = 0.98). Greater fatigability of the knee extensor muscles was associated with postexercise reductions in twitch amplitude ( r = 0.64, P = 0.001) and lesser exercise-induced hyperemia ( r = -0.56, P = 0.009). Patients with T2DM had greater lower-limb fatigability during dynamic exercise, which was associated with reduced contractile function and lower skeletal muscle blood flow. Thus, treatments focused on enhancing perfusion and reversing impairments in contractile function in patients with T2DM may offset lower-limb fatigability and aid in increasing exercise capacity. NEW & NOTEWORTHY Although prior studies compare patients with type 2 diabetes mellitus (T2DM) with lean controls, our study includes controls matched for age, body mass, and physical activity to more closely assess the effects of T2DM. Patients with T2DM demonstrated no impairment in macrovascular endothelial function, evidenced by similar flow-mediated dilation to controls. However, patients with T2DM had greater fatigability and reduced exercise-induced increase in blood flow (hyperemia) after a lower-limb dynamic fatiguing exercise compared with controls.
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Affiliation(s)
- Jonathon W Senefeld
- Clinical and Translational Rehabilitation Health Sciences Program, Marquette University , Milwaukee, Wisconsin.,Department of Physical Therapy, Marquette University , Milwaukee, Wisconsin
| | - Jacqueline K Limberg
- Department of Nutrition and Exercise Physiology, University of Missouri , Columbia, Missouri
| | - Kathleen M Lukaszewicz
- Clinical and Translational Rehabilitation Health Sciences Program, Marquette University , Milwaukee, Wisconsin.,Department of Physical Therapy, Marquette University , Milwaukee, Wisconsin
| | - Sandra K Hunter
- Clinical and Translational Rehabilitation Health Sciences Program, Marquette University , Milwaukee, Wisconsin.,Department of Physical Therapy, Marquette University , Milwaukee, Wisconsin
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“Alternative” fuels contributing to mitochondrial electron transport: Importance of non-classical pathways in the diversity of animal metabolism. Comp Biochem Physiol B Biochem Mol Biol 2018; 224:185-194. [DOI: 10.1016/j.cbpb.2017.11.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 11/08/2017] [Accepted: 11/10/2017] [Indexed: 12/19/2022]
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40
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Spainhower KB, Cliffe RN, Metz AK, Barkett EM, Kiraly PM, Thomas DR, Kennedy SJ, Avey-Arroyo JA, Butcher MT. Cheap labor: myosin fiber type expression and enzyme activity in the forelimb musculature of sloths (Pilosa: Xenarthra). J Appl Physiol (1985) 2018; 125:799-811. [PMID: 29722617 DOI: 10.1152/japplphysiol.01118.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sloths are canopy-dwelling inhabitants of American neotropical rainforests that exhibit suspensory behaviors. These abilities require both strength and muscular endurance to hang for extended periods of time; however, the skeletal muscle mass of sloths is reduced, thus requiring modifications to muscle architecture and leverage for large joint torque. We hypothesize that intrinsic muscle properties are also modified for fatigue resistance and predict a heterogeneous expression of slow/fast myosin heavy chain (MHC) fibers that utilize oxidative metabolic pathways for economic force production. MHC fiber type distribution and energy metabolism in the forelimb muscles of three-toed ( Bradypus variegatus, n = 5) and two-toed ( Choloepus hoffmanni, n = 4) sloths were evaluated using SDS-PAGE, immunohistochemistry, and enzyme activity assays. The results partially support our hypothesis by a primary expression of the slow MHC-1 isoform as well as moderate expression of fast MHC-2A fibers, whereas few hybrid MHC-1/2A fibers were found in both species. MHC-1 fibers were larger in cross-sectional area (CSA) than MHC-2A fibers and comprised the greatest percentage of CSA in each muscle sampled. Enzyme assays showed elevated activity for the anaerobic enzymes creatine kinase and lactate dehydrogenase compared with low activity for aerobic markers citrate synthase and 3-hydroxyacetyl CoA dehydrogenase. These findings suggest that sloth forelimb muscles may rely heavily on rapid ATP resynthesis pathways, and lactate accumulation may be beneficial. The intrinsic properties observed match well with suspensory requirements, and these modifications may have further evolved in unison with low metabolism and slow movement patterns as means to systemically conserve energy. NEW & NOTEWORTHY Myosin heavy chain (MHC) fiber type and fiber metabolic properties were evaluated to understand the ability of sloths to remain suspended for extended periods without muscle fatigue. Broad distributions of large, slow MHC-1 fibers as well as small, fast MHC-2A fibers are expressed in sloth forelimbs, but muscle metabolism is generally not correlated with myosin fiber type or body size. Sloth muscles rely on rapid, anaerobic pathways to resist fatigue and sustain force production.
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Affiliation(s)
- Kyle B Spainhower
- Department of Biological Sciences, Youngstown State University, Youngstown, Ohio
| | - Rebecca N Cliffe
- Department of Biosciences, Swansea University, Wales, United Kingdom
| | - Allan K Metz
- Department of Biological Sciences, Youngstown State University, Youngstown, Ohio
| | - Ernest M Barkett
- Department of Biological Sciences, Youngstown State University, Youngstown, Ohio
| | - Paije M Kiraly
- Department of Biological Sciences, Youngstown State University, Youngstown, Ohio
| | - Dylan R Thomas
- Department of Biological Sciences, Youngstown State University, Youngstown, Ohio
| | - Sarah J Kennedy
- Sloth Conservation Foundation, Puerto Viejo de Talamanca, Limon, Costa Rica
| | | | - Michael T Butcher
- Department of Biological Sciences, Youngstown State University, Youngstown, Ohio
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41
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Charter ME, Lamb IR, Murrant CL. Arteriolar and capillary responses to CO2and H+in hamster skeletal muscle microvasculature: Implications for active hyperemia. Microcirculation 2018; 25:e12494. [DOI: 10.1111/micc.12494] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 06/21/2018] [Accepted: 07/18/2018] [Indexed: 12/20/2022]
Affiliation(s)
- Mackenzie E. Charter
- Department of Human Health and Nutritional Sciences; University of Guelph; Guelph Ontario Canada
| | - Iain R. Lamb
- Department of Human Health and Nutritional Sciences; University of Guelph; Guelph Ontario Canada
| | - Coral L. Murrant
- Department of Human Health and Nutritional Sciences; University of Guelph; Guelph Ontario Canada
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42
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Broxterman RM, Hureau TJ, Layec G, Morgan DE, Bledsoe AD, Jessop JE, Amann M, Richardson RS. Influence of group III/IV muscle afferents on small muscle mass exercise performance: a bioenergetics perspective. J Physiol 2018; 596:2301-2314. [PMID: 29644702 DOI: 10.1113/jp275817] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 03/28/2018] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS This investigation assessed the influence of group III/IV muscle afferents on small muscle mass exercise performance from a skeletal muscle bioenergetics perspective. Group III/IV muscle afferent feedback was attenuated with lumbar intrathecal fentanyl during intermittent isometric single-leg knee-extensor all-out exercise, while 31 P-MRS was used to assess skeletal muscle bioenergetics. Attenuation of group III/IV muscle afferent feedback improved exercise performance during the first minute of exercise, due to an increase in total ATP production with no change in the ATP cost of contraction. However, exercise performance was not altered during the remainder of the protocol, despite a sustained increase in total ATP production, due to an exacerbated ATP cost of contraction. These findings reveal that group III/IV muscle afferents directly limit exercise performance during small muscle mass exercise, but, due to their critical role in maintaining skeletal muscle contractile efficiency, with time, the benefit of attenuating the muscle afferents is negated. ABSTRACT The direct influence of group III/IV muscle afferents on exercise performance remains equivocal. Therefore, all-out intermittent isometric single-leg knee-extensor exercise and phosphorous magnetic resonance spectroscopy (31 P-MRS) were utilized to provide a high time resolution assessment of exercise performance and skeletal muscle bioenergetics in control conditions (CTRL) and with the attenuation of group III/IV muscle afferent feedback via lumbar intrathecal fentanyl (FENT). In both conditions, seven recreationally active men performed 60 maximal voluntary quadriceps contractions (MVC; 3 s contraction, 2 s relaxation), while knee-extensor force and 31 P-MRS were assessed during each MVC. The cumulative integrated force was significantly greater (8 ± 6%) in FENT than CTRL for the first minute of the all-out protocol, but was not significantly different for the second to fifth minutes. Total ATP production was significantly greater (16 ± 21%) in FENT than CTRL throughout the all-out exercise protocol, due to a significantly greater anaerobic ATP production (11 ± 13%) in FENT than CTRL with no significant difference in oxidative ATP production. The ATP cost of contraction was not significantly different between FENT and CTRL for the first minute of the all-out protocol, but was significantly greater (29 ± 34%) in FENT than in CTRL for the second to fifth minutes. These findings reveal that group III/IV muscle afferents directly limit exercise performance during small muscle mass exercise, but, due to their critical role in maintaining skeletal muscle contractile efficiency, with time, the benefit from muscle afferent attenuation is negated.
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Affiliation(s)
- Ryan M Broxterman
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Thomas J Hureau
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Gwenael Layec
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Center on Aging, University of Utah, Salt Lake City, UT, USA
| | - David E Morgan
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Markus Amann
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Center on Aging, University of Utah, Salt Lake City, UT, USA.,Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, Salt Lake City VAMC, UT, USA.,Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Center on Aging, University of Utah, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
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Moll K, Gussew A, Nisser M, Derlien S, Krämer M, Reichenbach JR. Comparison of metabolic adaptations between endurance- and sprint-trained athletes after an exhaustive exercise in two different calf muscles using a multi-slice 31 P-MR spectroscopic sequence. NMR IN BIOMEDICINE 2018; 31:e3889. [PMID: 29393546 DOI: 10.1002/nbm.3889] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 10/20/2017] [Accepted: 12/03/2017] [Indexed: 06/07/2023]
Abstract
Measurements of exercise-induced metabolic changes, such as oxygen consumption, carbon dioxide exhalation or lactate concentration, are important indicators for assessing the current performance level of athletes in training science. With exercise-limiting metabolic processes occurring in loaded muscles, 31 P-MRS represents a particularly powerful modality to identify and analyze corresponding training-induced alterations. Against this background, the current study aimed to analyze metabolic adaptations after an exhaustive exercise in two calf muscles (m. soleus - SOL - and m. gastrocnemius medialis - GM) of sprinters and endurance athletes by using localized dynamic 31 P-MRS. In addition, the respiratory parameters VO2 and VCO2 , as well as blood lactate concentrations, were monitored simultaneously to assess the effects of local metabolic adjustments in the loaded muscles on global physiological parameters. Besides noting obvious differences between the SOL and the GM muscles, we were also able to identify distinct physiological strategies in dealing with the exhaustive exercise by recruiting two athlete groups with opposing metabolic profiles. Endurance athletes tended to use the aerobic pathway in the metabolism of glucose, whereas sprinters produced a significantly higher peak concentration of lactate. These global findings go along with locally measured differences, especially in the main performer GM, with sprinters revealing a higher degree of acidification at the end of exercise (pH 6.29 ± 0.20 vs. 6.57 ± 0.21). Endurance athletes were able to partially recover their PCr stores during the exhaustive exercise and seemed to distribute their metabolic activity more consistently over both investigated muscles. In contrast, sprinters mainly stressed Type II muscle fibers, which corresponds more to their training orientation preferring the glycolytic energy supply pathway. In conclusion, we were able to analyze the relation between specific local metabolic processes in loaded muscles and typical global adaptation parameters, conventionally used to monitor the training status of athletes, in two cohorts with different sports orientations.
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Affiliation(s)
- Kevin Moll
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Philosophenweg 3, Jena, Germany
| | - Alexander Gussew
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Philosophenweg 3, Jena, Germany
| | - Maria Nisser
- Institute of Physiotherapy, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany
| | - Steffen Derlien
- Institute of Physiotherapy, Jena University Hospital - Friedrich Schiller University Jena, Jena, Germany
| | - Martin Krämer
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Philosophenweg 3, Jena, Germany
| | - Jürgen R Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital - Friedrich Schiller University Jena, Philosophenweg 3, Jena, Germany
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44
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Broxterman RM, Layec G, Hureau TJ, Morgan DE, Bledsoe AD, Jessop JE, Amann M, Richardson RS. Bioenergetics and ATP Synthesis during Exercise: Role of Group III/IV Muscle Afferents. Med Sci Sports Exerc 2018; 49:2404-2413. [PMID: 28767527 DOI: 10.1249/mss.0000000000001391] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
PURPOSE The purpose of this study was to investigate the role of the group III/IV muscle afferents in the bioenergetics of exercising skeletal muscle beyond constraining the magnitude of metabolic perturbation. METHODS Eight healthy men performed intermittent isometric knee-extensor exercise to task failure at ~58% maximal voluntary contraction under control conditions (CTRL) and with lumbar intrathecal fentanyl to attenuate group III/IV leg muscle afferents (FENT). Intramuscular concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), diprotonated phosphate (H2PO4), adenosine triphosphate (ATP), and pH were determined using phosphorous magnetic resonance spectroscopy (P-MRS). RESULTS The magnitude of metabolic perturbation was significantly greater in FENT compared with CTRL for [Pi] (37.8 ± 16.8 vs 28.6 ± 8.6 mM), [H2PO4] (24.3 ± 12.2 vs 17.9 ± 7.1 mM), and [ATP] (75.8% ± 17.5% vs 81.9% ± 15.8% of baseline), whereas there was no significant difference in [PCr] (4.5 ± 2.4 vs 4.4 ± 2.3 mM) or pH (6.51 ± 0.10 vs 6.54 ± 0.14). The rate of perturbation in [PCr], [Pi], [H2PO4], and pH was significantly faster in FENT compared with CTRL. Oxidative ATP synthesis was not significantly different between conditions. However, anaerobic ATP synthesis, through augmented creatine kinase and glycolysis reactions, was significantly greater in FENT than in CTRL, resulting in a significantly greater ATP cost of contraction (0.049 ± 0.016 vs 0.038 ± 0.010 mM·min·N). CONCLUSION Group III/IV muscle afferents not only constrain the magnitude of perturbation in intramuscular Pi, H2PO4, and ATP during small muscle mass exercise but also seem to play a role in maintaining efficient skeletal muscle contractile function in men.
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Affiliation(s)
- Ryan M Broxterman
- 1Geriatric Research, Education, and Clinical Center, Salt Lake City Veteran's Affairs Medical Center, Salt Lake City, UT; 2Department of Internal Medicine, University of Utah, Salt Lake City, UT; 3Department of Anesthesiology, University of Utah, Salt Lake City, UT; and 4Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT
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Hureau TJ, Weavil JC, Thurston TS, Broxterman RM, Nelson AD, Bledsoe AD, Jessop JE, Richardson RS, Wray DW, Amann M. Identifying the role of group III/IV muscle afferents in the carotid baroreflex control of mean arterial pressure and heart rate during exercise. J Physiol 2018; 596:1373-1384. [PMID: 29388218 DOI: 10.1113/jp275465] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 01/29/2018] [Indexed: 02/05/2023] Open
Abstract
KEY POINTS We investigated the contribution of group III/IV muscle afferents to carotid baroreflex resetting during electrically evoked (no central command) and voluntary (requiring central command) isometric knee extension exercise. Lumbar intrathecal fentanyl was used to attenuate the central projection of μ-opioid receptor-sensitive group III/IV leg muscle afferent feedback. Spontaneous carotid baroreflex control was assessed by loading and unloading the carotid baroreceptors with a variable pressure neck chamber. Group III/IV muscle afferents did not influence spontaneous carotid baroreflex responsiveness at rest or during exercise. Afferent feedback accounted for at least 50% of the exercise-induced increase in the carotid baroreflex blood pressure and heart rate operating points, adjustments that are critical for an appropriate cardiovascular response to exercise. These findings suggest that group III/IV muscle afferent feedback is, independent of central command, critical for the resetting of the carotid baroreflex blood pressure and heart rate operating points, but not for spontaneous baroreflex responsiveness. ABSTRACT This study sought to comprehensively investigate the role of metabolically and mechanically sensitive group III/IV muscle afferents in carotid baroreflex responsiveness and resetting during both electrically evoked (EVO, no central command) and voluntary (VOL, requiring central command) isometric single-leg knee-extension (15% of maximal voluntary contraction; MVC) exercise. Participants (n = 8) were studied under control conditions (CTRL) and following lumbar intrathecal fentanyl injection (FENT) to inhibit μ-opioid receptor-sensitive lower limb muscle afferents. Spontaneous carotid baroreflex control of mean arterial pressure (MAP) and heart rate (HR) were assessed following rapid 5 s pulses of neck pressure (NP, +40 mmHg) or suction (NS, -60 mmHg). Resting MAP (87 ± 10 mmHg) and HR (70 ± 8 bpm) were similar between CTRL and FENT conditions (P > 0.4). In terms of spontaneous carotid baroreflex responsiveness, FENT did not alter the change in MAP or HR responses to NP (+13 ± 5 mmHg, P = 0.85; +9 ± 3 bpm; P = 0.99) or NS (-13 ± 5 mmHg, P = 0.99; -24 ± 11 bpm; P = 0.49) at rest or during either exercise protocol, which were of a remarkably similar magnitude to rest. In contrast, FENT administration reduced the exercise-induced resetting of the operating point for MAP and HR during both EVO (116 ± 10 mmHg to 100 ± 15 mmHg and 93 ± 14 bpm to 82 ± 10 bpm) and VOL (107 ± 13 mmHg to 100 ± 17 mmHg and 89 ± 10 bpm to 72 ± 10 bpm) exercise bouts. Together, these findings document that group III/IV muscle afferent feedback is critical for the resetting of the carotid baroreflex MAP and HR operating points, independent of exercise-induced changes in central command, but not for spontaneous carotid baroreflex responsiveness.
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Affiliation(s)
- Thomas J Hureau
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Joshua C Weavil
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Taylor S Thurston
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Ryan M Broxterman
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA
| | - Ashley D Nelson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
| | - Russell S Richardson
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - D Walter Wray
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA
| | - Markus Amann
- Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.,Geriatric Research, Education, and Clinical Center, Salt Lake City VA Medical Center, Salt Lake City, UT, USA.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, UT, USA.,Department of Anesthesiology, University of Utah, Salt Lake City, UT, USA
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Felippe LC, Ferreira GA, Learsi SK, Boari D, Bertuzzi R, Lima-Silva AE. Caffeine increases both total work performed above critical power and peripheral fatigue during a 4-km cycling time trial. J Appl Physiol (1985) 2018; 124:1491-1501. [PMID: 29470151 DOI: 10.1152/japplphysiol.00930.2017] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The link between total work performed above critical power (CP) and peripheral muscle fatigue during self-paced exercise is unknown. We investigated the influence of caffeine on the total work done above CP during a 4-km cycling time trial (TT) and the subsequent consequence on the development of central and peripheral fatigue. Nine cyclists performed three constant-load exercise trials to determine CP and two 4-km TTs ~75 min after oral caffeine (5 mg/kg) or cellulose (placebo) ingestion. Neuromuscular functions were assessed before and 50 min after supplementation and 1 min after TT. Oral supplementation alone had no effect on neuromuscular function ( P > 0.05). Compared with placebo, caffeine increased mean power output (~4%, P = 0.01) and muscle recruitment (as inferred by EMG, ~17%, P = 0.01) and reduced the time to complete the TT (~2%, P = 0.01). Work performed above CP during the caffeine trial (16.7 ± 2.1 kJ) was significantly higher than during the placebo (14.7 ± 2.1 kJ, P = 0.01). End-exercise decline in quadriceps twitch force (pre- to postexercise decrease in twitch force at 1 and 10 Hz) was more pronounced after caffeine compared with placebo (121 ± 13 and 137 ± 14 N vs. 146 ± 13 and 156 ± 11 N; P < 0.05). There was no effect of caffeine on central fatigue. In conclusion, caffeine increases muscle recruitment, which enables greater work performed above CP and higher end-exercise peripheral locomotor muscle fatigue. NEW & NOTEWORTHY The link between total work done above critical power and peripheral fatigue during a self-paced, high-intensity exercise is unclear. This study revealed that caffeine ingestion increases muscle recruitment, which enables greater work done above critical power and a greater degree of end-exercise decline in quadriceps twitch force during a 4-km cycling time trial. These findings suggest that caffeine increases performance at the expense of greater locomotor muscle fatigue.
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Affiliation(s)
| | | | - Sara Kely Learsi
- Sport Science Research Group, Federal University of Pernambuco , Pernambuco , Brazil
| | - Daniel Boari
- Center of Engineering, Modeling, and Applied Social Science, Federal University of ABC , São Paulo , Brazil
| | - Romulo Bertuzzi
- Endurance Performance Research Group (GEDAE-USP), University of São Paulo , São Paulo , Brazil
| | - Adriano Eduardo Lima-Silva
- Sport Science Research Group, Federal University of Pernambuco , Pernambuco , Brazil.,Human Performance Research Group, Technological Federal University of Parana, Parana, Brazil
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Abdalla LHP, Denadai BS, Bassan NM, Greco CC. Exercise tolerance during muscle contractions below and above the critical torque in different muscle groups. Appl Physiol Nutr Metab 2018; 43:174-179. [DOI: 10.1139/apnm-2017-0381] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The objective of this study was to test the hypotheses that end-test torque (ET) (expressed as % maximal voluntary contraction; MVC) is higher for plantar flexors (PF) than knee extensors (KE) muscles, whereas impulse above ET (IET) is higher for KE than PF. Thus, we expected that exercise tolerance would be longer for KE than PF only during the exercise performed above ET. After the determination of MVC, 40 men performed two 5-min all-out tests to determine ET and IET. Eleven participants performed a further 4 intermittent isometric tests, to exhaustion, at ET + 5% and ET – 5%, and 1 test for KE at the exercise intensity (%MVC) corresponding to ET + 5% of PF. The IET (7243.2 ± 1942.9 vs. 3357.4 ± 1132.3 N·m·s) and ET (84.4 ± 24.8 vs. 73.9 ± 19.5 N·m) were significantly lower in PF compared with KE. The exercise tolerance was significantly longer for PF (300.7 ± 156.7 s) than KE (156.7 ± 104.3 s) at similar %MVC (∼60%), and significantly shorter for PF (300.7 ± 156.7 s) than KE (697.0 ± 243.7 s) at ET + 5% condition. However, no significant difference was observed for ET – 5% condition (KE = 1030.2 ± 495.4 s vs. PF = 1028.3 ± 514.4 s). Thus, the limit of tolerance during submaximal isometric contractions is influenced by absolute MVC only during exercise performed above ET, which seems to be explained by differences on both ET (expressed as %MVC) and IET values.
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Affiliation(s)
- Leonardo Henrique Perinotto Abdalla
- Human Performance Laboratory, São Paulo State University (UNESP), Av. 24A, 1515, Bela Vista, CEP - 13506-900, Rio Claro, SP., Brazil
- Human Performance Laboratory, São Paulo State University (UNESP), Av. 24A, 1515, Bela Vista, CEP - 13506-900, Rio Claro, SP., Brazil
| | - Benedito Sérgio Denadai
- Human Performance Laboratory, São Paulo State University (UNESP), Av. 24A, 1515, Bela Vista, CEP - 13506-900, Rio Claro, SP., Brazil
- Human Performance Laboratory, São Paulo State University (UNESP), Av. 24A, 1515, Bela Vista, CEP - 13506-900, Rio Claro, SP., Brazil
| | - Natália Menezes Bassan
- Human Performance Laboratory, São Paulo State University (UNESP), Av. 24A, 1515, Bela Vista, CEP - 13506-900, Rio Claro, SP., Brazil
- Human Performance Laboratory, São Paulo State University (UNESP), Av. 24A, 1515, Bela Vista, CEP - 13506-900, Rio Claro, SP., Brazil
| | - Camila Coelho Greco
- Human Performance Laboratory, São Paulo State University (UNESP), Av. 24A, 1515, Bela Vista, CEP - 13506-900, Rio Claro, SP., Brazil
- Human Performance Laboratory, São Paulo State University (UNESP), Av. 24A, 1515, Bela Vista, CEP - 13506-900, Rio Claro, SP., Brazil
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Denadai BS, Greco CC. Resistance training and exercise tolerance during high-intensity exercise: moving beyond just running economy and muscle strength. J Appl Physiol (1985) 2017; 124:526-528. [PMID: 28982948 DOI: 10.1152/japplphysiol.00800.2017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
| | - Camila Coelho Greco
- Human Performance Laboratory, Paulista State University, Rio Claro, SP, Brazil
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