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Exercise tolerance during muscle contractions below and above the critical torque in different muscle groups

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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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ARTICLE
Exercise tolerance during muscle contractions below and
above the critical torque in different muscle groups
Leonardo Henrique Perinotto Abdalla, Benedito Sérgio Denadai, Natália Menezes Bassan,
and Camila Coelho Greco
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 partici-
pants 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.
Key words: maximal voluntary contraction, exercise, isometric, muscle volume, fatigue, exercise intensity domain.
Résumé : Cette étude a pour objectif de vérifier les hypothèses selon lesquelles le moment de force a
`la fin du test ET », exprimé
en % de la contraction maximale volontaire, « MVC ») est plus élevé chez les fléchisseurs plantaires PF ») comparativement aux
extenseurs du genou KE ») alors que l’impulsion au-dessus d’ET IET ») est plus élevée chez les KE comparativement aux PF. En
conséquence, on s’attend a
`ce que la tolérance a
`l’effort des KE soit plus élevée que celle des PF au cours d’un exercice effectué
au-dessus d’ET. On demande a
`40 hommes dont on a évalué la MVC d’effectuer deux tests de 5 min a
`fond de train afin de
déterminer ET et IET. Onze participants effectuent en outre 4 tests isométriques intermittents a
`ET+5%etET–5%jusqu’a
`
épuisement et effectuent aussi un test des KE a
`l’intensité d’effort (% MVC) correspondant a
`ET+5%dePF.IET(7243,2 ± 1942,9
vs 3357,4 ± 1132,3 N·m·s) et ET (84,4 ± 24,8 vs 73,9 ± 19,5 N·m) sont significativement plus faibles chez PF comparativement aux
KE. La tolérance a
`l’effort est significativement plus grande chez PF (300,7 ± 156,7 s) comparativement a
`KE (156,7 ± 104,3 s) a
`un
même % MVC (60 %) et significativement plus petite chez PF (300,7 ± 156,7 s) comparativement a
`KE (697,0 ± 243,7 s) dans la
condition ET+5%.Toutefois, on ne note pas de différence significative dans la condition ET–5%(KE=1030,2 ± 495,4 s vs PF =
1028,3 ± 514,4 s). Ainsi, la limite de la tolérance au cours de contractions isométriques sous-maximales est influencée par la MVC
absolue seulement au cours d’un exercice effectué au-dessus d’ET ; ce phénomène serait aux différences de valeurs d’ET
(exprimé en % MVC) et d’IET. [Traduit par la Rédaction]
Mots-clés : contraction maximale volontaire, exercice physique, isométrique, volume musculaire, fatigue, domaine de l’intensité
de l’effort.
Introduction
Exercise tolerance during different high-intensity exercise pro-
tocols (i.e., constant work rate, incremental, self-paced, and all-
out) can be predicted by a hyperbolic work rate/time function (i.e.,
critical power model) (Chidnok et al. 2013;Souza et al. 2015). Using
this function, it is possible to estimate both the critical power (the
asymptote of the power/time hyperbola) and the hyperbola’s cur-
vature constant (W=)(Dekerle et al. 2015). Critical power has been
considered the lower boundary of severe intensity domain and
corresponds to the highest sustainable rate of oxidative metabo-
lism. The W=represents the total amount of work that can be
performed above critical power before exhaustion occurs. Tradi-
tionally, critical power and W=and those equivalent for running
and swimming (critical velocity and D=, respectively), have been
estimated by 3–5 high-intensity constant work-rate exercises
(Jones et al. 2010). Aiming to reduce the number of bouts of ex-
haustive exercise, Vanhatalo et al. (2007) demonstrated that the
parameters of critical power model can be estimated by a single
3-min all-out exercise test. In this protocol, the end-test power (the
power output in the last 30 s of the test) and the work done above
end-test power were similar to the parameters (critical power and
W=, respectively) estimated during the conventional protocol (i.e.,
constant work-rate exercises).
Recently, some studies have utilized 5-min all-out intermittent
isometric single-leg knee-extensor exercise to characterize mus-
cle bioenergetics and fatigue (Burnley et al. 2012;Broxterman
et al. 2017). Moreover, this protocol has been utilized to estimate
the critical force/torque during exercise involving different mus-
Received 16 June 2017. Accepted 3 October 2017.
L.H.P. Abdalla, B.S. Denadai, N.M. Bassan, and C.C. Greco. Human Performance Laboratory, São Paulo State University (UNESP), Av. 24A, 1515,
Bela Vista, CEP - 13506-900, Rio Claro, SP., Brazil.
Corresponding author: Camila Coelho Greco (email: grecocc@rc.unesp.br).
Copyright remains with the author(s) or their institution(s). Permission for reuse (free in most cases) can be obtained from RightsLink.
174
Appl. Physiol. Nutr. Metab. 43: 174–179 (2018) dx.doi.org/10.1139/apnm-2017-0381 Published at www.nrcresearchpress.com/apnm on 12 October 2017.
... The torquetime to task failure relationship, equivalent to the powertime to task failure relationship, for small muscle mass isometric exercise is hyperbolic and has important implications for human performance (Abdalla et al., 2018;Burnley, 2009). The asymptote of this hyperbola for intermittent isometric exercise is end-test torque (ET; analogous to critical power), which represents the highest attainable metabolic steady-state (Jones et al., 2008;Poole et al., 1988). ...
... Participants performed a 5-min all-out test consisting of a series of 60 MVC (3 s exercise, 2 s rest) (Abdalla et al., 2018;Burnley, 2009). Before the test, a warm-up was performed with a set of five submaximal isometric contractions (∼70-80% MVC) followed by a 5 min rest and three MVC of 3 s interspersed by 3 min of rest. ...
... After 30 min of rest, the target torque was displayed on a screen for the participants, and they were instructed to attain and maintain the target torque for 3 s. Task failure was determined by the first of three consecutive contractions where the participant was unable to achieve the target torque despite strong encouragement (Abdalla et al., 2018). Throughout each submaximal test, neuromuscular function was assessed every 12 contractions (i.e. 1 min) and immediately after task failure. ...
Article
We previously reported that creatine supplementation improved intermittent isometric exercise performance by augmenting the total impulse performed above end‐test torque (total IET′). However, our previous analyses did not enable mechanistic assessments. The objective of this study was to determine if creatine supplementation affected the IET′ speed of recovery. To achieve this objective, we retrospectively analyzed our data using the IET′ balance model to determine the time constant for the recovery of IET′ ( τ IET′). Sixteen men were randomly allocated into creatine ( N = 8) or placebo ( N = 8) groups. Prior to supplementation, participants performed quadriceps all‐out exercise to determine end‐test torque (ET) and IETʹ. Participants then performed quadriceps exercise at ET + 10% until task‐failure before supplementation (Baseline), until task‐failure after supplementation (Creatine or Placebo), and until the Baseline time after supplementation (Creatine‐ or Placebo‐Isotime). τ IET′ was faster than Baseline for Creatine (669 ± 98 vs 470 ± 66 s), but not Placebo (792 ± 166 vs 786 ± 161 s). The creatine‐induced change in τ IET′ was inversely correlated with the creatine‐induced changes in both the rate of peripheral fatigue development and time to task‐failure. τ IET′ was inversely correlated with total IET′ and ET in all conditions, but creatine supplementation shifted this relationship such that τ IET′ was faster for a given ET. Creatine supplementation, therefore, sped the recovery of IET′ during intermittent isometric exercise, which was inversely related to the improvement in exercise performance. These findings support that the improvement in exercise performance after creatine supplementation was, at least in part, specific to effects on the physiological mechanisms that determine the IET′ speed of recovery.
... Thus, the mechanical occlusion of perfusion in the contracting muscle occurs at a specific absolute force (Barnes, 1980). Consistent with this, the T lim during isometric muscle contractions is significantly greater for plantar flexor (PF) (301 s) than knee extensor (KE) (157 s) muscles, despite exercising at similar percentages of MVC (∼60%) (Abdalla et al., 2018). It has also been demonstrated that the hyperbolic torque-T lim relationships differ between the severe and extreme domains, with these relationships merging at ∼60% of maximal strength (Alexander et al., 2019). ...
... For the 5 min all-out tests, ET was determined as the mean of the final six contractions and IETʹ was determined as cumulative area under the torque versus time curve above ET (Abdalla et al., 2018;Burnley, 2009). The data were analysed using MatLab R2017a software (The MathWorks Inc., Natick, MA, USA). ...
... In the present study, a 5-min all-out intermittent test was utilized to predict IET′ and ET, requiring fewer laboratory visits. It is important to note that this test has been already used to successfully predict the critical power model parameters in previous studies conducted in whole body (Vanhatalo et al., 2007) and small muscle mass (Abdalla et al., 2018;Burnley, 2009) It is generally accepted that there is a close relationship between the muscular cross-sectional area (CSA) and its ability to generate force (Fukunaga et al., 1996;Ikai & Fukunaga, 1968;Maughan et al., 1983;Young et al., 1985). Muscle strength is related to its physiological CSA (PCSA), which can be estimated from muscle volume, muscle length and pennation angle. ...
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New findings: What is the central question of this study? Does muscle size, maximal force and exercise intensity influence the recovery time constant for the finite impulse above critical torque (τIET')? What is the main finding and its importance? This study showed that muscle size and maximal strength have different influences on the parameters of the hyperbolic torque - Tlim relationship. Greater muscle size and maximal strength, as well as exercise at an intensity of 60% MVC, prolong τIET' during intermittent isometric exercise. Abstract: Muscle perfusion and O2 delivery limitations through muscle force generation appear to play a major role in defining the hyperbolic torque - Tlim relationship. Therefore, we aimed to determine the influence of muscle size and maximal strength on the recovery time constant for the finite impulse above critical torque (τIET'). Ten men participated in the study and performed intermittent isometric tests until task-failure (Tlim ) for the knee-extensors (KE 35% and 60% MVC) and plantar flexors (PF 60% MVC). The τIET' was determined for each of these Tlim tests using the IET'BAL model. The IET' (9738 ± 3080 vs 2959 ± 1289 N · m · s) and ET (84.5 ± 7.1 vs 74.3 ± 12.7 N · m) were significantly lower for PF compared to KE (P < 0.05). Exercise tolerance (Tlim ) was significantly longer for PF (239 ± 81 s) than KE (150 ± 55 s) at 60% MVC, and significantly longer for KE at 35% MVC (641 ± 158 s) than 60% MVC. The τIET' was significantly faster at 35% MVC (641± 177 s) than 60% MVC (1840 ± 354 s) for KE, both of which were significantly slower than PF 60% MVC (317 ± 102 s). This study showed that τIET' during intermittent isometric exercise is slower with greater muscle size and maximal strength. This article is protected by copyright. All rights reserved.
... The tolerance to high-intensity exercises is well-described by the critical power model, which suggests a hyperbolic relationship between the intensity of the exercise and the total duration that it can be sustained [3]. Two parameters can be derived from this relationship: the asymptote for the intensity measure (i.e., critical power, critical speed, or critical torque, CT) and the curvature constant (W prime, W ′ ), which together allow the estimation of the tolerance to exercises performed above critical power [4,5]. Physiologically, the critical power/CT represents the highest rate at which oxidative metabolism stabilizes and is considered the boundary between the heavy and severe-intensity domains as well as a threshold for neuromuscular fatigue [6,7]. ...
... Previous evidence demonstrates that the intensity associated with CT during handgrip exercise in untrained subjects is strongly influenced by oxygen availability, since when the oxygen supply is reduced, CT also decreases [9,10]. On the other hand, Bassan et al. (2019) [5] showed that when a short-term strength training program is performed, increases in both W ′ and tolerance to severe-intensity exercise occur without changes in CT. Hence, the first hypothesis of the present study is that GCS fighters would have a greater W ′ but a similar CT compared to the untrained individuals. ...
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Successful performance in grappling combat sports (GCS) can be influenced by the fighter's capacity to sustain high-intensity contractions of the handgrip muscles during combat. This study investigated the influence of GCS experience on the critical torque (CT), impulse above CT (W ′), tolerance, and neuromuscular fatigue development during severe-intensity handgrip exercise by comparing fighters and untrained individuals. Eleven GCS fighters and twelve untrained individuals participated in three experimental sessions for handgrip muscles: (1) familiarization with the experimental procedures and strength assessment; (2) an all-out test to determine CT and W ′ ; and (3) intermittent exercise performed in the severe-intensity domain (CT + 15%) until task failure. No significant differences were found in CT and neuromuscular fatigue between groups (p > 0.05). However, GCS fighters showed greater W ′ (GCS fighters 2238.8 ± 581.2 N·m·s vs. untrained 1670.4 ± 680.6 N·m·s, p < 0.05) and exercise tolerance (GCS fighters 8.38 ± 2.93 min vs. untrained 5.36 ± 1.42 min, p < 0.05) than untrained individuals. These results suggest that long-term GCS sports training can promote increased tolerance to severe-intensity handgrip exercise and improved W ′ without changes in CT or the magnitude of neuromuscular fatigue.
... The curvature of the power or load versus time to exhaustion hyperbola represents the work or load prime which is the total work that can be performed above critical power/load (Bergstrom et al. 2021). While the concepts of critical power/load and work/load prime have been extensively studied in both en-durance exercise and isometric contractions (Poole et al. 2016;Abdalla et al. 2018), their application to isotonic contractions, which are used in traditional RET, has been limited (Morton, Redstone and Laing 2014;Dinyer et al. 2019;Dinyer et al. 2020b). In other domains, such as endurance exercise, different training styles have divergent effects on critical power and work prime (Gaesser and Wilson 1988;Quigley 1992, 1993;Sawyer et al. 2014). ...
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The effect of resistance training with higher- and lower-loads on muscle mass and strength has been extensively studied, while changes in muscle endurance have received less attention. This trial aimed to assess the effect of training load on absolute muscle endurance (AME) and relative muscle endurance (RME). Sixteen untrained women (22.7 ± 3.3 yr: mean ± SD) had one arm and leg randomly assigned to train with higher loads (HL; 80–90% 1RM), and the contralateral limbs trained with lower loads (LL; 30–50% 1RM) thrice weekly to volitional fatigue for 10 weeks. Heavy and light load AME and RME, strength, and muscle mass were assessed pre- and post-training. Strength increased more in the HL compared to LL leg (P < 0.01), but similar increases in strength were observed between upper body conditions (P = 0.46). Lower body heavy and light load AME improved in both conditions, but HL training induced a larger improvement in heavy load AME (HL: 9.3 ± 4.3 vs. LL: 7.5 ± 7.1 repetitions, time × limb P < 0.01) and LL training induced a larger improvement in light load AME (LL: 24.7 ± 22.2 vs. HL: 15.2 ± 16.7 repetitions, time × limb P = 0.04). In the upper body, HL and LL training induced similar increases in both heavy (time × limb P = 0.99), and light load (time × limb P = 0.16) AME. Dual-energy X-ray absorptiometry showed no change in leg fat-and-bone-free mass (FBFM) for either condition, and an increase in only LL arm FBFM. AME improved in a manner specific to the training loads used. ClinicalTrials.gov (NCT04547972).
... Theoretically, once this stable state is reached, it can be maintained indefinitely. The mean relative force asymptotes measured in the present study (FFs, 42.4% of MVC; PFs, 43.0% of MVC; not statistically different) are similar to those reported in previous studies for FFs (40.3% of MVC; Veni et al., 2018) and PFs (40.9% of MVC;Abdalla et al., 2018). Although these data are similar, it is important to note the high inter-individual variability (range, ∼20-70% of MVC for both muscle groups). ...
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Le cancer et ses traitements entraînent un certain nombre d’effet secondaire qui impacte la qualité de vie des patients. Le principal effet secondaire est la fatigue liée au cancer (FLC), sa prévalence se situe entre 59 et 99% des patients, en fonction du type de cancer et de traitement. La FLC est définie comme une sensation persistante d’épuisement due au cancer et à ses traitements, qui n’est pas proportionnelle aux activités réalisées. Etant subjective, la FLC est évaluée par le biais de questionnaires. Cependant, cette modalité d’évaluation ne permet de prendre en compte les différents mécanismes sous-jacents de la FLC. Car en effet, il est communément admis que de multiples mécanismes appartenant aux dimensions physique, psychologique, sociale et comportementale peuvent être à l’origine de la FLC. Parmi les principales origines décrites dans la littérature, on retrouve les troubles du sommeil et les symptômes émotionnels d’anxiété et de dépression. Il semblerait également que la fatigabilité soit un mécanisme potentiel de la FLC, néanmoins les résultats des précédentes études sont équivoques. Par conséquent, l’objectif de ce travail de thèse est d’affirmer les liens entre la FLC et la fatigabilité et déterminer si la fatigabilité fait parti des mécanismes sous-jacents de la FLC. Pour répondre à ces objectifs, nous avons mis en place différentes expérimentations et proposé un protocole de recherche qui sera prochainement mis en place. Les principaux résultats de ces études sont que i) la fatigabilité semble être une caractéristique individuelle ; ii) l’amplitude de la fatigabilité est associée à la FLC ; et iii) la fatigabilité est un des mécanismes sous-jacents de la FLC.
... Burnley [2009] examined 5 min of maximum intermittent isometric contractions to determine critical torque of the knee extensors and showed that end-torque of these tests closely approximates CT. All-out tests have also been used for other exercises, e.g., for plantar flexion [Abdalla et al., 2018] or for handgrip exercise [Kellawan and Tschakovsky, 2014]. However, some authors have reported a possible overestimation of CP by the equivalent 3-min all-out test [Muniz-Pumares et al., 2018], which suggests that all-out tests might not be suitable for all subjects or might need to be adapted individually. ...
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