Isometric versus isotonic contractions: Sex differences in the fatigability and recovery of isometric strength and high-velocity contractile parameters.

Autor: Ha PL; Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA, USA., Dalton BE; Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA, USA., Alesi MG; Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA, USA., Smith TM; Department of Molecular and Cellular Biology, Kennesaw State University, Kennesaw, GA, USA., VanDusseldorp TA; Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA, USA., Feito Y; Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA, USA., Hester GM; Department of Exercise Science and Sport Management, Kennesaw State University, Kennesaw, GA, USA.
Jazyk: angličtina
Zdroj: Physiological reports [Physiol Rep] 2021 May; Vol. 9 (9), pp. e14821.
DOI: 10.14814/phy2.14821
Abstrakt: The purpose of this study was to investigate potential sex differences in the fatigue- and recovery-induced responses of isometric strength and power, as well as select dynamic contractile parameters after isometric and isotonic plantar flexor (PF) contractions. Healthy males (n = 12; age = 21.8 ± 2.2 years) and females (n = 14; age = 21.4 ± 2.5 years) performed a 2-min maximal voluntary isometric contraction and 120 concentric isotonic (30% peak isometric torque) contractions of the PFs on separate visits. Isometric strength, isotonic power, as well as torque- and velocity-related parameters were recorded before, immediately after, and throughout 10 min of recovery. Rate of EMG rise (RER) for the medial gastrocnemius (MG) and soleus was also obtained. All measures responded similarly between sexes after both fatiguing modalities (p > 0.05), except RER of the MG which, in males demonstrated both, a greater decrease during isotonic contractions (p = 0.038, η p 2  = 0.174) and more rapid recovery after isometric exercise (p = 0.043, η p 2  = 0.166). Although not significant, a nearly large effect size was demonstrated for the fatigue-induced decrease in isometric strength (p = 0.061; d = 0.77) due to relative decreases tending to be greater in males (-29% vs. -17%). Regardless of fatiguing modality, sex differences were minimal for fatigue and recovery-related responses in muscle function for the PFs, although the difference for RER may indicate a unique origin of fatigue. Further support for the disassociation between the response in isometric strength and power after fatiguing exercise was also demonstrated.
(© 2021 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)
Databáze: MEDLINE
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