Effects Of Hip Abductor Fatigue On Static And Dynamic Postural Control For Subjects With Different Sex

Objective:The hip abductor is the main muscle of core stability,which is essential to pelvic stability during single-leg supporting.The deficiency of hip abductor function may change the biomechanics of the lower extremities,and then affect the postural stability.In addition,the differences of sex may influence the postural control.The aim of this study was to through hip abductor weakness induced by fatigue exploring the basic regular characteristics of the 3D kinematic and kinetic variables of the lower extremities and muscle activity and postural stability during static and dynamic postural task between male and female,discussing the effects of hip abductor fatigue on static and dynamic postural stability and its motor coordination strategy with different sex.Methods:Twenty female adults and twenty male adults were recruited.The three dimensional kinematic,kinetic and myoelectrical variables of the lower extremities in single-leg stance and single-leg side-jump landing comparing before and after hip abductor fatigue were collected using a Vicon motion capture system（100Hz,Vicon T40,Oxford Metrics,UK）.AMTI force plates（100Hz,Vicon T40,Oxford Metrics,UK）and Wireless surface electromyography system（2000Hz,Noraxon,USA）.These data were further processed using visual 3D software and expressed as mean±standard deviation.Statistical analysis was performed using SPSS 25.0 software.These data were analyzed using two way（sex×fatigue）repeated measures-ANOVA.The significance level was set at p<0.05.Results:（1）The features of COP during static posture task before and after fatigue group by sex:During single-leg stance with eyes-open,there were significant differences in l＿COP（p<0.001）and v＿COP_ML（p=0.001）in male before and after fatigue.There were significant differences in l＿COP（p=0.037）and v＿COP_ML（p=0.016）between male and female after fatigue.The v＿COP_AP（p=0.016）was significant before and after fatigue.There were significant differences in s＿COP（p=0.002）,d＿COP_AP（p=0.031）,d＿COP_ML（p=0.001）between male and female.During single-leg stance with eyes-close,there were significant differences in l＿COP（p<0.001）,s＿COP（p<0.001）,d＿COP_AP（p=0.003）,d＿COP_ML（p<0.001）,v＿COP_AP（p<0.001）,v＿COP_ML（p<0.001）in male before and after fatigue.There were significant differences in s＿COP（p=0.023）and d＿COP_ML（p=0.001）between male and female before fatigue.There were significant differences in l＿COP（p=0.001）,s＿COP（p<0.001）,d＿COP_AP（p=0.002）,d＿COP_ML（p<0.001）,v＿COP_AP（p=0.003）,v＿COP_ML（p<0.001）between male and female after fatigue.（2）The features of surface EMG during static posture task before and after fatigue group by sex:During single-leg stance with eyes-open,the RMS of GM（p=0.004）,LG（p=0.025）,PL（p=0.014）were significant before and after fatigue.There were significant differences in the RMS of LG（p=0.04）,PL（p=0.034）in male before and after fatigue.During single-leg stance with eyes-close,the RMS of GM（p<0.001）was significant before and after fatigue.There was significant difference in the RMS of PL（p=0.026）in male before and after fatigue.（3）The features of COP during dynamic posture task before and after fatigue group by sex:During single-leg side-jump landing,there was significant difference in d＿COP_AP（p=0.035）in male before and after fatigue.There was significant difference in d＿COP_AP（p=0.008）in male before fatigue.The d＿COP_ML（p=0.003）and v＿COP_ML（p=0.027）were significant before and after fatigue.There were significant differences in l＿COP（p=0.021）and s＿COP（p=0.001）between male and female.（4）The features of surface EMG during dynamic posture task before and after fatigue group by sex:During single-leg side-jump landing,the peak angle of hip abduction（p=0.013）and ankle eversion（p=0.01）were significant before and after fatigue.There were significant differences in the peak angle of hip flexion（p=0.024）and hip abduction（p=0.023）between male and female.（5）The characteristics of kinematic during dynamic posture task before and after fatigue group by sex:During single-leg side-jump landing,there was significant difference in TPv GRF（p=0.034）in female before and after fatigue.There was significant difference in p＿GRF（p=0.027）between male and female.The peak torque of hip extension（p=0.018）and ankle inversion（p<0.001）were significant before and after fatigue.There was significant difference in the peak torque of ankle plantar flexion（p=0.048）between male and female.（6）The characteristics of kinetic during dynamic posture task before and after fatigue group by sex:At the 200-ms pre-landing of single-leg side-jump,the RMS of GM（p=0.047）was significant before and after fatigue.There were significant differences in the RMS of RF（p=0.004）,BF（p=0.014）,TA（p<0.001）,PL（p=0.008）between male and female.At the 200-ms post-landing of single-leg side-jump,there were significant differences in the RMS of GM（p=0.003）and TA（p=0.05）in male before and after fatigue.There was significant difference in the RMS of TA（p=0.045）between male and female before and after fatigue.The RMS of LG（p=0.023）were significant before and after fatigue.There were significant differences in the RMS of BF（p=0.019）and PL（p<0.001）between male and female.Conclusions:（1）The static postural stability decreased after hip abductor fatigue in male.There was no decrease in static postural stability observed in female.There were differences in postural control strategies between male and female.Female was more dependent on the ankle strategy during single-leg standing.（2）The dynamic postural stability in frontal plane decreased after hip abductor fatigue.The neuromuscular control impaired after fatigue,and the joint stability in frontal plane decreased.There were differences in postural control strategies between male and female.Anticipatory postural adjustments strategy was stronger in female than in male.And female performed a softer landing strategy.