Neuromuscular Movement Control Of The Upper Trapezius In Patients With Chronic Neck Pain Based SEMG

Objective:The purpose of the study is to examine the neuromuscular movement control of the upper trapezius in patients with chronic neck pain under internal posture perturbation condition,and investigate the subjective psychological predictive effect and local muscle fatigue effect of that.Methods:Twenty patients with chronic neck pain(CNP)and 20 age-matched healthy controls(HC)were recruited in the study.Electromyography was acquired from the bilateral upper trapezius(UT)and right anterior deltoid(AD).The pre-action time,average EMG of anticipatory posture adjustment(APAs)and compensatory posture adjustment(CPAs)were calculated during rapid,unilateral arm movements,and with a load of 1kg/2kg in right hand.Subjects performed bilateral shoulder elevations with loads(20 kg for men and 10 kg for women)until exhausted and recorded the duration.After fatigue,participants immediately repeated the Arm-raising test to examine the fatigue effect on the APAs and CPAs.Results:EMG dates from 17 chronic neck pain and 19 healthy group were obtained.The ipsilateral upper trapezius demonstrated feed-forward activation(activation within 50 ms of deltoid onset)during rapid,unilateral arm movements in both CNP group and HP group,whereas the contralateral UT activated after 50 ms of deltoid onset.Although significant differences were not identified for the both sides upper trapezius in both CNP group and HP group,there was a trend for delayed activation and decreased APAs EMG activity in the ipsilateral upper trapezius of the CNP group compared with HP group.With the increased the magnitude of perturbation,there was a trend for early activation and increased APAs EMG activity in HP group,and for delayed activation in CNP group,which were lack significance.And there were not found significant differences between in CNP group and HP group.Compared with healthy controls,the average duration of the upper trapezius significantly shorter in CNP group,and there had increased left MFs and MPFs、right MPFs and decreased righr MPF value.After fatigue test,there were no significant differences in both sides upper trapezius of both two groups compared with before fatigue test,also between in CNP group and HP group.However,the ipsilateral upper trapezius appeared a trend for delayed activation in both groups,while APAs and CPAs EMG activity demonstrated a decreased trend in HP group and a increased tread.Conclusion:The ipsilateral upper trapezius demonstrated feed-forward activation in both CNP group and HP group under the internal posture perturbation condition,which illustrate the neuromotor control strategy to stabilized the head and cervical spine by pre-activation.These findings may indicate underlying motor control impairments in patients with chronic neck pain.In the study,there were not have been observed the subjective psychological predictive effect and local muscle fatigue effect on the neuromotor control of the upper trapezius in both groups.Besides,the CNP group showed more fatigability than HP group.Further studies are needed to verify the evidence of motor control impairments of the upper trapezius in patients with chronic neck pain,which have significant implications for rehabilitation for patients with neck pain.