Coactivation Does Not Contribute to Fatigue-Induced Decreases in Isokinetic Forearm Flexion and Extension Torque  

作　　者：Tyler J.Neltner John Paul V.Anders Robert W.Smith Jocelyn E.Arnett Joshua L.Keller Terry J.Housh Richard J.Schmidt Glen O.Johnson 

机构地区：[1]Department of Nutrition and Health Sciences,University of Nebraska-Lincoln,Lincoln,NE 68510,USA [2]Integrative Laboratory of Exercise and Applied Physiology(iLEAP),Department of Health,Kinesiology and Sport,University of South Alabama,Mobile,AL 36688,USA

出　　处：《Journal of Science in Sport and Exercise》2023年第4期314-321,共8页体育运动科学（英文）

摘　　要：Purpose The present study examined the effects of a reciprocal,slow velocity forearm flexion and extension task on fatigue-induced changes in isokinetic torque,agonist and antagonist muscle activation,and coactivation ratios at slow and moderate velocities.Methods Nine women(mean±SD:age=21.0±1.7 years;body mass=68.1±8.2 kg;height=167.4±7.2 cm)completed pre-testing for forearm flexion and extension isokinetic peak torque at 60 and 180°/s,a fatiguing task of 50 maximal,recip-rocal,isokinetic muscle actions at 60°/s,and post-testing.The amplitude(AMP)of the electromyographic(EMG)signals from the biceps and triceps were simultaneously recorded.Torque and EMG AMP were normalized to the corresponding values from the pre-testing peak torque movements.Repeated measures ANOVAs and pairwise comparisons were used to identify mean changes in torque,EMG AMP,and coactivation ratios.Results The torque analyses indicated significant decreases from pre-to post-testing for forearm flexion(14.1%±5.0%;P<0.001)and extension(25.4%±12.2%;P<0.001)at 60°.At 180°/s there was a significant decrease,collapsed across the forearm movements(24.7%±11.7%;P<0.001).For EMG AMP and coactivation ratios,there were no changes(P>0.05)from pre-to post-testing for either velocity or movement.Conclusions The torque responses were velocity-specific,with greater fatigability exhibited for forearm extension versus flexion at 60°/s,but no differences at 180°/s.The parallel EMG AMP responses between the agonist and antagonist muscles for both velocities supported the lack of fatigue-induced changes in coactivation ratios.Thus,our results demonstrated that fatigue-induced decreases in torque were not attributable to increases in antagonist activation or coactivation.

关 键 词：COACTIVATION ISOKINETIC FATIGUE Forearm flexion Extension 

分 类 号：G804[文化科学—运动人体科学]