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Broxterman RM, Craig JC, Weavil JC, Hureau TJ. The relationship between W' and peripheral fatigue considered. Exp Physiol 2019; 105:211-212. [PMID: 31762122 DOI: 10.1113/ep088239] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 10/15/2019] [Indexed: 11/08/2022]
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Hureau TJ, Weavil JC, Thurston TS, Wan HY, Gifford JR, Jessop JE, Buys MJ, Richardson RS, Amann M. Pharmacological attenuation of group III/IV muscle afferents improves endurance performance when oxygen delivery to locomotor muscles is preserved. J Appl Physiol (1985) 2019; 127:1257-1266. [PMID: 31513446 DOI: 10.1152/japplphysiol.00490.2019] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We sought to investigate the role of group III/IV muscle afferents in limiting endurance exercise performance, independently of their role in optimizing locomotor muscle O2 delivery. While breathing 100% O2 to ensure a similar arterial O2 content ([Formula: see text]) in both trials, eight male cyclists performed 5-km time trials under control conditions (HCTRL) and with lumbar intrathecal fentanyl (HFENT) impairing neural feedback from the lower limbs. After each time trial, common femoral artery blood flow (FBF) was quantified (Doppler ultrasound) during constant-load cycling performed at the average power of the preceding time trial. The assessment of end-tidal gases, hemoglobin content and saturation, and FBF facilitated the calculation of leg O2 delivery. Locomotor muscle activation during cycling was estimated from vastus lateralis EMG. With electrical femoral nerve stimulation, peripheral and central fatigue were quantified by pre- to postexercise decreases in quadriceps twitch torque (ΔQtw) and voluntary activation (ΔVA), respectively. FBF (~16 mL·min-1·W-1; P = 0.6), [Formula: see text] (~24 mL O2/dL; P = 0.9), and leg O2 delivery (~0.38 mL O2·min-1·W-1; P = 0.9) were not different during HCTRL and HFENT. Mean power output and time to completion were significantly improved by 9% (~310 W vs. ~288 W) and 3% (~479 s vs. ~463 s), respectively, during HFENT compared with HCTRL. Quadriceps muscle activation was 9 ± 7% higher during HFENT compared with HCTRL (P < 0.05). ΔQtw was significantly greater in HFENT compared with HCTRL (54 ± 8% vs. 39 ± 9%), whereas ΔVA was not different (~5%; P = 0.3) in both trials. These findings reveal that group III/IV muscle afferent feedback limits whole body endurance exercise performance and peripheral fatigue by restricting neural activation of locomotor muscle.NEW & NOTEWORTHY Group III/IV muscle afferent feedback facilitates endurance performance by optimizing locomotor muscle O2 delivery but also limits performance by restricting neural drive to locomotor muscle. To isolate the performance-limiting effect of these sensory neurons, we pharmacologically attenuated their central projection during a cycling time trial while controlling for locomotor muscle O2 delivery. With no difference in leg O2 delivery, afferent blockade attenuated the centrally mediated restriction in motoneuronal output and improved cycling performance.
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Zarzissi S, Zghal F, Bouzid MA, Hureau TJ, Sahli S, Ben Hassen H, Rebai H. Centrally-mediated regulation of peripheral fatigue during knee extensor exercise and consequences on the force-duration relationship in older men. Eur J Sport Sci 2019; 20:641-649. [PMID: 31397211 DOI: 10.1080/17461391.2019.1655099] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The aim of the present study was to investigate the existence of a critical threshold beyond which peripheral fatigue would not further decrease during knee extensor (KE) exercise in older men, and the consequences of this mechanism on the force-duration relationship. Twelve old men (59 ± 2 years) randomly performed two different sessions, in which they performed 60 maximum voluntary contractions (MVC; 3s contraction, 2s relaxation). One trial was performed in the unfatigued state (CTRL) and one other following fatiguing neuromuscular electrical stimulation of the KE (FNMES). Peripheral and central fatigue were quantified via pre/post-exercise decreases in quadriceps twitch-force (Δ Ptw) and voluntary activation (ΔVA). Critical torque (CT) was determined as the mean force of the last 12 contractions while W' was calculated as the area above CT. Compared with CTRL, pre-fatigue (Δ Ptw = -10.3 ± 6.2%) resulted in a significant (p < 0.05) reduction in W' (-18.2 ± 1.6%) in FNMES. However, CT (∼964 N), ΔVA (∼15%) and Δ Ptw (∼25%) post-MVCs were similar between both conditions. In CTRL, W' was correlated with Δ Ptw (r 2 = 0.78). Moreover, the difference in W' between CTRL and FNMES was correlated with the level of pre-fatigue induced in FNMES (r 2 = 0.76). These findings document that peripheral fatigue is confined to an individual threshold during KE exercise in older men. Furthermore, correlative results suggest that mechanisms regulating peripheral fatigue to a critical threshold also restrict W', and therefore play a role in exercise capacity in older men.
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Layec G, Blain GM, Rossman MJ, Park SY, Hart CR, Trinity JD, Gifford JR, Sidhu SK, Weavil JC, Hureau TJ, Amann M, Richardson RS. Acute High-Intensity Exercise Impairs Skeletal Muscle Respiratory Capacity. Med Sci Sports Exerc 2019; 50:2409-2417. [PMID: 30102675 DOI: 10.1249/mss.0000000000001735] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE The effect of an acute bout of exercise, especially high-intensity exercise, on the function of mitochondrial respiratory complexes is not well understood, with potential implications for both the healthy population and patients undergoing exercise-based rehabilitation. Therefore, this study sought to comprehensively examine respiratory flux through the different complexes of the electron transport chain in skeletal muscle mitochondria before and immediately after high-intensity aerobic exercise. METHODS Muscle biopsies of the vastus lateralis were obtained at baseline and immediately after a 5-km time trial performed on a cycle ergometer. Mitochondrial respiratory flux through the complexes of the electron transport chain was measured in permeabilized skeletal muscle fibers by high-resolution respirometry. RESULTS Complex I + II state 3 (state 3CI + CII) respiration, a measure of oxidative phosphorylation capacity, was diminished immediately after the exercise (pre, 27 ± 3 ρm·mg·s; post, 17 ± 2 ρm·mg·s; P < 0.05). This decreased oxidative phosphorylation capacity was predominantly the consequence of attenuated complex II-driven state 3 (state 3CII) respiration (pre, 17 ± 1 ρm·mg·s; post, 9 ± 2 ρm·mg·s; P < 0.05). Although complex I-driven state 3 (3CI) respiration was also lower (pre, 20 ± 2 ρm·mg·s; post, 14 ± 4 ρm·mg·s), this did not reach statistical significance (P = 0.27). In contrast, citrate synthase activity, proton leak (state 2 respiration), and complex IV capacity were not significantly altered immediately after the exercise. CONCLUSIONS These findings reveal that acute high-intensity aerobic exercise significantly inhibits skeletal muscle state 3CII and oxidative phosphorylation capacity. This, likely transient, mitochondrial defect might amplify the exercise-induced development of fatigue and play an important role in initiating exercise-induced mitochondrial adaptations.
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Broxterman RM, Layec G, Hureau TJ, Morgan DE, Bledsoe AD, Jessop JE, Amann M, Richardson RS. Response. Med Sci Sports Exerc 2019; 50:1719. [PMID: 30005058 DOI: 10.1249/mss.0000000000001606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Angius L, Crisafulli A, Hureau TJ, Broxterman RM, Amann M, Incognito AV, Burr JF, Millar PJ, Jones H, Thijssen DJ, Patterson SD, Jeffries O, Waldron M, Silva BM, Lopes TR, Vianna LC, Smith JR, Copp SW, Van Guilder GP, Zuo L, Chuang CC. Commentaries on Viewpoint: Could small-diameter muscle afferents be responsible for the ergogenic effect of limb ischemic preconditioning? J Appl Physiol (1985) 2018; 122:721-725. [PMID: 28302710 DOI: 10.1152/japplphysiol.00030.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 01/11/2017] [Indexed: 11/22/2022] Open
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Blain GM, Hureau TJ. Limitation of fatigue and performance during exercise: the brain-muscle interaction. Exp Physiol 2018; 102:3-4. [PMID: 28044405 DOI: 10.1113/ep085895] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Berg OK, Kwon OS, Hureau TJ, Clifton HL, Thurston T, Le Fur Y, Jeong EK, Amann M, Richardson RS, Trinity JD, Wang E, Layec G. Maximal strength training increases muscle force generating capacity and the anaerobic ATP synthesis flux without altering the cost of contraction in elderly. Exp Gerontol 2018; 111:154-161. [PMID: 30031838 DOI: 10.1016/j.exger.2018.07.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 07/09/2018] [Accepted: 07/18/2018] [Indexed: 01/09/2023]
Abstract
Aging is associated with a progressive decline in skeletal muscle function, then leading to impaired exercise tolerance. Maximal strength training (MST) appears to be a practical and effective intervention to increase both exercise capacity and efficiency. However, the underlying physiological mechanisms responsible for these functional improvements are still unclear. Accordingly, the purpose of this study was to examine the intramuscular and metabolic adaptations induced by 8 weeks of knee-extension MST in the quadriceps of 10 older individuals (75 ± 9 yrs) by employing a combination of molecular, magnetic resonance 1H-imaging and 31P-spectroscopy, muscle biopsies, motor nerve stimulation, and indirect calorimetry techniques. Dynamic and isometric muscle strength were both significantly increased by MST. The greater torque-time integral during sustained isometric maximal contraction post-MST (P = 0.002) was associated with increased rates of ATP synthesis from anaerobic glycolysis (PRE: 10 ± 7 mM·min-1; POST: 14 ± 7 mM·min-1, P = 0.02) and creatine kinase reaction (PRE: 31 ± 10 mM·min-1; POST: 41 ± 10 mM·min-1, P = 0.006) such that the ATP cost of contraction was not significantly altered. Expression of fast myosin heavy chain, quadriceps muscle volume, and submaximal cycling net efficiency were also increased with MST (P = 0.005; P = 0.03 and P = 0.03, respectively). Overall, MST induced a shift toward a more glycolytic muscle phenotype allowing for greater muscle force production during sustained maximal contraction. Consequently, some of the MST-induced improvements in exercise tolerance might stem from a greater anaerobic capacity to generate ATP, while the improvement in exercise efficiency appears to be independent from an alteration in the ATP cost of contraction.
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Weavil JC, Hureau TJ, Thurston TS, Sidhu SK, Garten RS, Nelson AD, McNeil CJ, Richardson RS, Amann M. Impact of age on the development of fatigue during large and small muscle mass exercise. Am J Physiol Regul Integr Comp Physiol 2018; 315:R741-R750. [PMID: 29995457 DOI: 10.1152/ajpregu.00156.2018] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
To examine the impact of aging on neuromuscular fatigue following cycling (CYC; large active muscle mass) and single-leg knee-extension (KE; small active muscle mass) exercise, 8 young (25 ± 4 years) and older (72 ± 6 years) participants performed CYC and KE to task failure at a given relative intensity (80% of peak power output). The young also matched CYC and KE workload and duration of the old (iso-work comparison). Peripheral and central fatigue were quantified via pre-/postexercise decreases in quadriceps twitch torque (∆Qtw, electrical femoral nerve stimulation) and voluntary activation (∆VA). Although young performed 77% and 33% more work during CYC and KE, respectively, time to task failure in both modalities was similar to the old (~9.5 min; P > 0.2). The resulting ΔQtw was also similar between groups (CYC ~40%, KE ~55%; P > 0.3); however, ∆VA was, in both modalities, approximately double in the young (CYC ~6%, KE ~9%; P < 0.05). While causing substantial peripheral and central fatigue in both exercise modalities in the old, ∆Qtw in the iso-work comparison was not significant (CYC; P = 0.2), or ~50% lower (KE; P < 0.05) in the young, with no central fatigue in either modality ( P > 0.4). Based on iso-work comparisons, healthy aging impairs fatigue resistance during aerobic exercise. Furthermore, comparisons of fatigue following exercise at a given relative intensity mask the age-related difference observed following exercise performed at the same workload. Finally, although active muscle mass has little influence on the age-related difference in the rate of fatigue at a given relative intensity, it substantially impacts the comparison during exercise at a given absolute intensity.
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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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Thurston TS, Weavil JC, Hureau TJ, Gifford JR, Richardson RS, Amann M. Effect of Intra-Venous Antioxidant Infusion on the Development of Neuromuscular Fatigue During Whole Body Exercise in Hypertensive Middle-Age Individuals. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000535858.11898.d4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hureau TJ, Weavil JC, Thurston TS, Wan HY, Gifford JR, Jessop JE, Buys MJ, Richardson RS, Amann M. Muscle Afferent Blockade Improves Endurance Exercise Performance When O2 Transport To Locomotor Muscles Is Pre- served. Med Sci Sports Exerc 2018. [DOI: 10.1249/01.mss.0000538796.56152.c9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Weavil JC, Hureau TJ, Thurston TS, Gifford JR, Richardson RS, Amann M. Impact of Aging on Inspiratory and Expiratory Work during Exercise. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.855.10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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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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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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Bertuzzi R, Gáspari AF, Trojbicz LR, Silva-Cavalcante MD, Lima-Silva AE, Billaut F, Girard O, Millet GP, Bossi AH, Hopker J, Pandeló DR, Fulton TJ, Paris HL, Chapman RF, Grosicki GJ, Murach KA, Hureau TJ, Dufour SP, Favret F, Kruse NT, Nicolò A, Sacchetti M, Pedralli M, Pinheiro FA, Tricoli V, Brietzke C, Pires FO, Sandford GN, Pearson S, Kilding AE, Ross A, Laursen PB, da Silveira ALB, Olivares EL, de Azevedo Cruz Seara F, Miguel-dos-Santos R, Mesquita TRR, Nelatury S, Vagula M. Commentaries on Viewpoint: Resistance training and exercise tolerance during high-intensity exercise: moving beyond just running economy and muscle strength. J Appl Physiol (1985) 2018; 124:529-535. [PMID: 29480788 DOI: 10.1152/japplphysiol.01064.2017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Hureau TJ, Broxterman RM, Weavil JC. The mechanistic basis of the power-time relationship: potential role of the group III/IV muscle afferents. J Physiol 2018; 594:7165-7166. [PMID: 27976395 DOI: 10.1113/jp273333] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
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Broxterman RM, Layec G, Hureau TJ, Morgan DE, Bledsoe AD, Jessop JE, Amann M, Richardson RS. Skeletal Muscle Force Production and Bioenergetics During All-out Exercise. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000519454.23113.c3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Thurston TS, Hureau TJ, Weavil JC, Gifford JR, Wan HY, La Salle DT, Richardson RS, Amann M. Effect Of Dietary Nitrate Supplementation On The Development Of Neuromuscular Fatigue During Whole Body Exercise. Med Sci Sports Exerc 2017. [DOI: 10.1249/01.mss.0000520003.46314.59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Broxterman RM, Layec G, Hureau TJ, Amann M, Richardson RS. Skeletal muscle bioenergetics during all-out exercise: mechanistic insight into the oxygen uptake slow component and neuromuscular fatigue. J Appl Physiol (1985) 2017; 122:1208-1217. [PMID: 28209743 DOI: 10.1152/japplphysiol.01093.2016] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 02/13/2017] [Accepted: 02/15/2017] [Indexed: 11/22/2022] Open
Abstract
Although all-out exercise protocols are commonly used, the physiological mechanisms underlying all-out exercise performance are still unclear, and an in-depth assessment of skeletal muscle bioenergetics is lacking. Therefore, phosphorus magnetic resonance spectroscopy (31P-MRS) was utilized to assess skeletal muscle bioenergetics during a 5-min all-out intermittent isometric knee-extensor protocol in eight healthy men. Metabolic perturbation, adenosine triphosphate (ATP) synthesis rates, ATP cost of contraction, and mitochondrial capacity were determined from intramuscular concentrations of phosphocreatine (PCr), inorganic phosphate (Pi), diprotonated phosphate ([Formula: see text]), and pH. Peripheral fatigue was determined by exercise-induced alterations in potentiated quadriceps twitch force (Qtw) evoked by supramaximal electrical femoral nerve stimulation. The oxidative ATP synthesis rate (ATPOX) attained and then maintained peak values throughout the protocol, despite an ~63% decrease in quadriceps maximal force production. ThusATPOX normalized to force production (ATPOX gain) significantly increased throughout the exercise (1st min: 0.02 ± 0.01, 5th min: 0.04 ± 0.01 mM·min-1·N-1), as did the ATP cost of contraction (1st min: 0.048 ± 0.019, 5th min: 0.052 ± 0.015 mM·min-1·N-1). Additionally, the pre- to postexercise change in Qtw (-52 ± 26%) was significantly correlated with the exercise-induced change in intramuscular pH (r = 0.75) and [Formula: see text] concentration (r = 0.77). In conclusion, the all-out exercise protocol utilized in the present study elicited a "slow component-like" increase in intramuscular ATPOX gain as well as a progressive increase in the phosphate cost of contraction. Furthermore, the development of peripheral fatigue was closely related to the perturbation of specific fatigue-inducing intramuscular factors (i.e., pH and [Formula: see text] concentration).NEW & NOTEWORTHY The physiological mechanisms and skeletal muscle bioenergetics underlying all-out exercise performance are unclear. This study revealed an increase in oxidative ATP synthesis rate gain and the ATP cost of contraction during all-out exercise. Furthermore, peripheral fatigue was related to the perturbation in pH and deprotonated phosphate ion. These findings support the concept that the oxygen uptake slow component arises from within active skeletal muscle and that skeletal muscle force generating capacity is linked to the intramuscular metabolic milieu.
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Hureau TJ, Romer LM, Amann M. The 'sensory tolerance limit': A hypothetical construct determining exercise performance? Eur J Sport Sci 2016; 18:13-24. [PMID: 27821022 DOI: 10.1080/17461391.2016.1252428] [Citation(s) in RCA: 136] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Neuromuscular fatigue compromises exercise performance and is determined by central and peripheral mechanisms. Interactions between the two components of fatigue can occur via neural pathways, including feedback and feedforward processes. This brief review discusses the influence of feedback and feedforward mechanisms on exercise limitation. In terms of feedback mechanisms, particular attention is given to group III/IV sensory neurons which link limb muscle with the central nervous system. Central corollary discharge, a copy of the neural drive from the brain to the working muscles, provides a signal from the motor system to sensory systems and is considered a feedforward mechanism that might influence fatigue and consequently exercise performance. We highlight findings from studies supporting the existence of a 'critical threshold of peripheral fatigue', a previously proposed hypothesis based on the idea that a negative feedback loop operates to protect the exercising limb muscle from severe threats to homeostasis during whole-body exercise. While the threshold theory remains to be disproven within a given task, it is not generalisable across different exercise modalities. The 'sensory tolerance limit', a more theoretical concept, may address this issue and explain exercise tolerance in more global terms and across exercise modalities. The 'sensory tolerance limit' can be viewed as a negative feedback loop which accounts for the sum of all feedback (locomotor muscles, respiratory muscles, organs, and muscles not directly involved in exercise) and feedforward signals processed within the central nervous system with the purpose of regulating the intensity of exercise to ensure that voluntary activity remains tolerable.
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Blain GM, Mangum TS, Sidhu SK, Weavil JC, Hureau TJ, Jessop JE, Bledsoe AD, Richardson RS, Amann M. Group III/IV muscle afferents limit the intramuscular metabolic perturbation during whole body exercise in humans. J Physiol 2016; 594:5303-15. [PMID: 27241818 DOI: 10.1113/jp272283] [Citation(s) in RCA: 119] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 05/16/2016] [Indexed: 12/27/2022] Open
Abstract
KEY POINTS The purpose of this study was to determine the role of group III/IV muscle afferents in limiting the endurance exercise-induced metabolic perturbation assayed in muscle biopsy samples taken from locomotor muscle. Lumbar intrathecal fentanyl was used to attenuate the central projection of μ-opioid receptor-sensitive locomotor muscle afferents during a 5 km cycling time trial. The findings suggest that the central projection of group III/IV muscle afferent feedback constrains voluntary neural 'drive' to working locomotor muscle and limits the exercise-induced intramuscular metabolic perturbation. Therefore, the CNS might regulate the degree of metabolic perturbation within locomotor muscle and thereby limit peripheral fatigue. It appears that the group III/IV muscle afferents are an important neural link in this regulatory mechanism, which probably serves to protect locomotor muscle from the potentially severe functional impairment as a consequence of severe intramuscular metabolic disturbance. ABSTRACT To investigate the role of metabo- and mechanosensitive group III/IV muscle afferents in limiting the intramuscular metabolic perturbation during whole body endurance exercise, eight subjects performed 5 km cycling time trials under control conditions (CTRL) and with lumbar intrathecal fentanyl impairing lower limb muscle afferent feedback (FENT). Vastus lateralis muscle biopsies were obtained before and immediately after exercise. Motoneuronal output was estimated through vastus lateralis surface electromyography (EMG). Exercise-induced changes in intramuscular metabolites were determined using liquid and gas chromatography-mass spectrometry. Quadriceps fatigue was quantified by pre- to post-exercise changes in potentiated quadriceps twitch torque (ΔQTsingle ) evoked by electrical femoral nerve stimulation. Although motoneuronal output was 21 ± 12% higher during FENT compared to CTRL (P < 0.05), time to complete the time trial was similar (∼8.8 min). Compared to CTRL, power output during FENT was 10 ± 4% higher in the first half of the time trial, but 11 ± 5% lower in the second half (both P < 0.01). The exercise-induced increase in intramuscular inorganic phosphate, H(+) , adenosine diphosphate, lactate and phosphocreatine depletion was 55 ± 30, 62 ± 18, 129 ± 63, 47 ± 14 (P < 0.001) and 27 ± 14% (P < 0.01) greater in FENT than CTRL. ΔQTsingle was greater following FENT than CTRL (-52 ± 2 vs -31 ± 1%, P < 0.001) and this difference was positively correlated with the difference in inorganic phosphate (r(2) = 0.79; P < 0.01) and H(+) (r(2) = 0.92; P < 0.01). In conclusion, during whole body exercise, group III/IV muscle afferents provide feedback to the CNS which, in turn, constrains motoneuronal output to the active skeletal muscle. This regulatory mechanism limits the exercise-induced intramuscular metabolic perturbation, preventing an abnormal homeostatic challenge and excessive peripheral fatigue.
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Mangum TS, Hureau TJ, Weavil JC, Sidhu SK, Thurston TS, Nelson AD, Richardson RS, Amann M. Ascorbate Attenuates the Development of Fatigue During Exercise in Patients with Chronic Obstructive Pulmonary Disease. Med Sci Sports Exerc 2016. [DOI: 10.1249/01.mss.0000485853.57265.c4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Mangum TS, Sidhu SK, Weavil JC, Hureau TJ, Richardson RS, Amann M. The Development of Peripheral and Central Fatigue During Self-Paced Endurance Exercise. Med Sci Sports Exerc 2015. [DOI: 10.1249/01.mss.0000477312.87170.08] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hureau TJ, Ducrocq GP, Blain GM. Peripheral And Central Fatigue Development And Short-term Recovery During All-out Repeated Sprints. Med Sci Sports Exerc 2015. [DOI: 10.1249/01.mss.0000477313.87170.41] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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