非预期性干扰对踝关节调节策略的影响

The Impact of Unanticipated Disturbances on Ankle Joint Control Strategies

目的:本研究以压力中心(COP)在前后方向上的速率特征为划分依据,探索非预期性重物摆干扰在COP不同运动阶段对踝关节调节过程的影响。方法:17名受试者单足站立于测力台上,实验人员分别在无提示和倒计时提示两种情况下释放悬吊于其后方天花板上的重物,通过无线表面肌电采集受试者胫骨前肌(TA)和腓肠肌(GAS)肌电,三维测力台用以记录受试者COP变化。结果:干扰前阶段,预期性干扰时两块肌肉RMS均高于非预期性干扰时(P<0.05);COP减速向前阶段,非预期性干扰时两块被测肌肉的RMS值都小于预期性干扰时,其中TA有显著性差异(P<0.05);COP减速向后阶段,两块肌肉在非预期干扰情况下的RMS值都高于预期时,其中TA有显著性差异(P<0.05)。结论:非预期性干扰不会引起TA和GAS的预激活;非预期性干扰会使TA在调整阶段产生更大的代偿性姿势调节,尤其在COP向后减速阶段。

OBJECTIVE:This study,using the rate characteristics of Center of Pressure(COP)in the anterior-posterior direction as a basis,explores the effects of unanticipated swinging loads on ankle joint regulation during different phases of COP.METHODS:Seventeen subjects stood on a force platform with one foot,and experimenters released a weight suspended from the ceiling behind them under two conditions:with and without countdown cues.Surface electromyography(EMG)was used to record the activity of the tibialis anterior(TA)and gastrocnemius(GAS)muscles,while a three-dimensional force platform tracked changes in COP.RESULTS:Prior to the disturbance,the root mean square(RMS)of both muscles was higher during expected perturbations compared to unexpected ones(P<0.05).During the forward COP deceleration phase,the RMS values of both measured muscles were lower during unexpected perturbations,with TA showing a significant difference(P<0.05).During the backward COP deceleration phase,the RMS values of both muscles were higher during unexpected perturbations,with TA displaying a significant difference(P<0.05).CONCLUSION:Unanticipated disturbances do not trigger pre-activation of the TA and GAS muscles.Instead,they lead to more pronounced compensatory posture adjustments in the TA during the adjustment phase,particularly during COP deceleration in the backward direction.