TY - JOUR
T1 - Contraction intensity and sex differences in knee-extensor fatigability
AU - Ansdell, Paul
AU - Thomas, Kevin
AU - Howatson, Glyn
AU - Hunter, Sandra
AU - Goodall, Stuart
PY - 2017/12
Y1 - 2017/12
N2 - Females are less fatigable than males during isometric contractions across various muscles and intensities. However, sex differences in knee-extensor fatigability remain relatively unexplored.
Purpose:To determine the sex difference in performance fatigability for intermittent, isometric contractions of the knee-extensor muscles.
Methods:Eighteen participants (10 males, 8 females) performed intermittent, isometric, knee-extensor contractions at 30% of their maximal voluntary force (MVC) for 30 min and in a separate session at 50% MVC until task-failure. During both fatiguing protocols a MVC was performed every 60s and electromyography (EMG) was recorded during all contractions.
Results:At task completion males had a larger reduction in MVC force for the 30% MVC task (−32±15% vs. −15±16%, P=0.042) and the 50% MVC task (−34±8% vs. −24±1%, P=0.045). Furthermore, for the 50% MVC task, females had a longer task duration (937±525 s vs. 397±153 s, P=0.007). The rise in EMG activity and force fluctuations were more rapid for the males than females (P<0.05). When participants were matched for strength post-hoc (n=10), a sex difference in fatigability for both tasks was still evident.
Conclusions:
Females were less fatigable than males during intermittent, isometric, knee-extensor contractions at moderate relative forces and this difference was independent of strength.
AB - Females are less fatigable than males during isometric contractions across various muscles and intensities. However, sex differences in knee-extensor fatigability remain relatively unexplored.
Purpose:To determine the sex difference in performance fatigability for intermittent, isometric contractions of the knee-extensor muscles.
Methods:Eighteen participants (10 males, 8 females) performed intermittent, isometric, knee-extensor contractions at 30% of their maximal voluntary force (MVC) for 30 min and in a separate session at 50% MVC until task-failure. During both fatiguing protocols a MVC was performed every 60s and electromyography (EMG) was recorded during all contractions.
Results:At task completion males had a larger reduction in MVC force for the 30% MVC task (−32±15% vs. −15±16%, P=0.042) and the 50% MVC task (−34±8% vs. −24±1%, P=0.045). Furthermore, for the 50% MVC task, females had a longer task duration (937±525 s vs. 397±153 s, P=0.007). The rise in EMG activity and force fluctuations were more rapid for the males than females (P<0.05). When participants were matched for strength post-hoc (n=10), a sex difference in fatigability for both tasks was still evident.
Conclusions:
Females were less fatigable than males during intermittent, isometric, knee-extensor contractions at moderate relative forces and this difference was independent of strength.
KW - electromyography
KW - force fluctuations
KW - muscle fatigue
KW - quadriceps
KW - sex differences
U2 - 10.1016/j.jelekin.2017.09.003
DO - 10.1016/j.jelekin.2017.09.003
M3 - Article
VL - 37
SP - 68
EP - 74
JO - Journal of Electromyography and Kinesiology
JF - Journal of Electromyography and Kinesiology
SN - 1050-6411
ER -