Chronic training status affects muscle excitation of the vastus lateralis during repeated contractions  

作　　者：Sunggun Jeon Stephanie A.Sontag Trent J.Herda Michael A.Trevino 

机构地区：[1]Applied Neuromuscular Physiology Laboratory,Department of Kinesiology,Applied Health,and Recreation,Oklahoma State University,Stillwater,OK,USA [2]Neuromechanics Laboratory,Department of Health,Sport,and Exercise Sciences,The University of Kansas,Lawrence,KS,USA

出　　处：《Sports Medicine and Health Science》2023年第1期42-49,共8页运动医学与健康科学（英文）

基　　金：granted by the Ethics Committee of University of Kansas(10-30-2012/HSCL#20495).

摘　　要：This study examined electromyographic amplitude(EMGRMS)-force relationships during repeated submaximal knee extensor muscle actions among chronic aerobically-(AT),resistance-trained(RT),and sedentary(SED)individuals.Fifteen adults(5/group)attempted 20 isometric trapezoidal muscle actions at 50%of maximal strength.Surface electromyography(EMG)was recorded from vastus lateralis(VL)during the muscle actions.For the first and last successfully completed contractions,linear regression models were fit to the log-transformed EMGRMS-force relationships during the linearly increasing and decreasing segments,and the b terms(slope)and a terms(antilog of y-intercept)were calculated.EMGRMS was averaged during steady force.Only the AT completed all 20 muscle actions.During the first contraction,the b terms for RT(1.3010.197)were greater than AT(0.9100.123;p?0.008)and SED(0.9120.162;p?0.008)during the linearly increasing segment,and in comparison to the linearly decreasing segment(1.0180.139;p?0.014),respectively.For the last contraction,the b terms for RT were greater than AT during the linearly increasing(RT?1.3730.353;AT?0.8830.129;p?0.018)and decreasing(RT?1.5260.328;AT?0.9700.223;p?0.010)segments.In addition,the b terms for SED increased from the linearly increasing(0.9680.144)to decreasing segment(1.2680.126;p?0.015).There were no training,segment,or contraction differences for the a terms.EMGRMS during steady force increased from the first-([64.0851.68]μV)to last-contraction([86.7349.55]μV;p?0.001)collapsed across training statuses.The b terms differentiated the rate of change for EMGRMS with increments in force among training groups,indicating greater muscle excitation to the motoneuron pool was necessary for the RT than AT during the linearly increasing and decreasing segments of a repetitive task.

关 键 词：ELECTROMYOGRAPHY Fatigue Isometric trapezoidal muscle action Motor unit control properties Natural log-transformed model Vastus lateralis 

分 类 号：G822.1[文化科学—体育训练]