Regional changes in muscle activity do not underlie the repeated bout effect in the human gastrocnemius muscle

2020 ◽  
Author(s):  
Patricio A. Pincheira ◽  
Eduardo Martinez‐Valdes ◽  
Rodrigo Guzman‐Venegas ◽  
Deborah Falla ◽  
Marta I. Garrido ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Gastrocnemius Muscle ◽  
Repeated Bout Effect ◽  
Repeated Bout

scholarly journals Investigating The Repeated-bout Effect To Eccentric Contractions For Females And Males

2019 ◽  
Vol 51 (Supplement) ◽  
pp. 83
Author(s):  
Christina D. Bruce ◽  
Luca Ruggiero ◽  
Gabriel U. Dix ◽  
Paul D. Cotton ◽  
Chris J. McNeil
Keyword(s):  
Eccentric Contractions ◽  
Repeated Bout Effect ◽  
Repeated Bout

scholarly journals The repeated bout effect can occur without mechanical and neuromuscular changes after a bout of eccentric exercise

2018 ◽  
Vol 28 (10) ◽  
pp. 2123-2134 ◽  
Author(s):  
P. A. Pincheira ◽  
B. W. Hoffman ◽  
A. G. Cresswell ◽  
T. J. Carroll ◽  
N. A. T. Brown ◽  
...  
Keyword(s):  
Eccentric Exercise ◽  
Repeated Bout Effect ◽  
Repeated Bout

Power loss is attenuated following a second bout of high intensity eccentric contractions due to the repeated bout effect’s protection of rate of torque and velocity development

2020 ◽  
Author(s):  
Avery Hinks ◽  
Adam Hess ◽  
Mathew I. B. Debenham ◽  
Jackey Chen ◽  
Nicole Mazara ◽  
...  
Keyword(s):  
Muscle Damage ◽  
Eccentric Exercise ◽  
High Intensity ◽  
Power Loss ◽  
Peak Power ◽  
Eccentric Contractions ◽  
Peak Power Output ◽  
Repeated Bout Effect ◽  
Maximum Voluntary Isometric Contraction ◽  
Repeated Bout

High intensity unaccustomed eccentric contractions result in weakness and power loss due to fatigue and muscle damage. Through the repeated bout effect (RBE), adaptations occur, then damage and weakness are attenuated following a subsequent bout. However, it is unclear whether the RBE protects peak power output. We investigated the influence of the RBE on power production and estimated fatigue- and damage-induced neuromuscular impairments following repeated high-intensity eccentric contractions. Twelve healthy adult males performed 5 sets of 30 maximal eccentric elbow flexions and repeated an identical bout 4 weeks later. Recovery was tracked over 7 days following both bouts. Reduced maximum voluntary isometric contraction torque, and increased serum creatine kinase and self-reported soreness indirectly inferred muscle damage. Peak isotonic power, time-dependent measures—rate of velocity development (RVD) and rate of torque development (RTD)—and several electrophysiological indices of neuromuscular function were assessed. The RBE protected peak power, with a protective index of 66% 24 hours after the second eccentric exercise bout. The protection of power also related to preserved RVD (R2=0.61, P<0.01) and RTD (R2=0.39, P<0.01). Furthermore, the RBE’s protection against muscle damage permitted the estimation of fatigue-associated neuromuscular performance decrements following eccentric exercise. Novelty Bullets • The repeated bout effect protects peak isotonic power. • Protection of peak power relates to preserved rates of torque and velocity development, but more so rate of velocity development. • The repeated bout effect has little influence on indices of neuromuscular fatigue.

Females and males do not differ for fatigability, muscle damage and magnitude of the repeated bout effect following maximal eccentric contractions

2020 ◽  
Author(s):  
Christina D. Bruce ◽  
Luca Ruggiero ◽  
Gabriel U. Dix ◽  
Paul D. Cotton ◽  
Chris J McNeil
Keyword(s):  
Muscle Fatigue ◽  
Muscle Damage ◽  
Low Frequency ◽  
Calcium Handling ◽  
High Frequency Stimulation ◽  
Repeated Bout Effect ◽  
Indirect Measure ◽  
Force Depression ◽  
Before And After ◽  
Repeated Bout

Unaccustomed eccentric (ECC) exercise induces muscle fatigue as well as damage and initiates a protective response to minimize impairments from a subsequent bout (i.e., repeated bout effect; RBE). It is uncertain if the sexes differ for neuromuscular responses to ECC exercise and the ensuing RBE. Twenty-six young adults (13 females) performed two bouts (four weeks apart) of 200 ECC maximal voluntary contractions (MVCs) of the dorsiflexors. Isometric (ISO) MVC torque and the ratio of ISO torque in response to low- vs. high-frequency stimulation (10:100Hz) were compared before and after (2-10min and 2, 4, and 7d) exercise. The decline in ECC and ISO MVC torque, and the 10:100Hz ratio following bout one did not differ between sexes (P > 0.05), with reductions from baseline of 31.5 ± 12.3, 24.1 ± 15.4, and 51.3 ± 12.2%, respectively. After bout two, the 10:100Hz ratio declined less (45.0 ± 12.4% from baseline) and ISO MVC torque recovered sooner compared to bout one but no differences between sexes were evident for the magnitude of the RBE (P > 0.05). These data suggest that fatigability with ECC exercise does not differ for the sexes and adaptations that mitigate impairments to calcium handling are independent of sex. NOVELTY BULLETS: • One bout of 200 maximal eccentric dorsiflexor contractions caused equivalent muscle fatigue and damage for females and males • The repeated bout effect observed after a second bout four weeks later also had no sex-related differences • Prolonged low-frequency force depression is promoted as an indirect measure of muscle damage in humans

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