Eccentric exercise-induced muscle weakness abolishes sex differences in fatigability during sustained submaximal isometric contractions  

作　　者：Hanna L.Jodoin Avery Hinks Olivia P.Roussel Vincenzo S.Contento Brian H.Dalton Geoffrey A.Power 

机构地区：[1]Department of Human Health and Nutritional Sciences,College of Biological Sciences,University of Guelph,Guelph,ON N1G 2W1,Canada [2]School of Health and Exercise Science,University of British Columbia,Kelowna,BC V1V 1V7,Canada

出　　处：《Journal of Sport and Health Science》2023年第4期523-533,共11页运动与健康科学（英文）

基　　金：supported by the Natural Sciences and Engineering Research Council of Canada(NSERC)。

摘　　要：Background:Females are typically less fatigable than males during sustained isometric contractions at lower isometric contraction intensities.This sex difference in fatigability becomes more variable during higher intensity isometric and dynamic contractions.While less fatiguing than isometric or concentric contractions,eccentric contractions induce greater and longer lasting impairments in force production.However,it is not clear how muscle weakness influences fatigability in males and females during sustained isometric contractions.Methods:We investigated the effects of eccentric exercise-induced muscle weakness on time to task failure(TTF)during a sustained submaximal isometric contraction in young(18-30 years)healthy males(n=9)and females(n=10).Participants performed a sustained isometric contraction of the dorsiflexors at 35°plantar flexion by matching a 30%maximal voluntary contraction(MVC)torque target until task failure(i.e.,falling below 5%of their target torque for>2 s).The same sustained isometric contraction was repeated 30 min after 150 maximal eccentric contractions.Agonist and antagonist activation were assessed using surface electromyography over the tibialis anterior and soleus muscles,respectively.Results:Males were~41%stronger than females.Following eccentric exercise both males and females experienced an~20%decline in maximal voliuntary contraction torque.TTF was-34%longer in females than males prior to eccentic exercise-induced muscle weakness.However,following eccentric exercise-induced muscle weakness,this sex-related difference was abolished,with both groups having an"45%shorter TTF.Notably,there was~100%greater antagonist activation in the female group during the sustained isometric contraction following exercise-induced weakness as compared to the males.Conclusion:This increase in antagonist activation disadvantaged females by decreasing their TTF,resulting in a blunting of their typical fatigability advantage over males.

关 键 词：Fatigue ISOMETRIC SEX Time to task failure WEAKNESS 

分 类 号：G804.2[文化科学—运动人体科学]