A Surface Electromyography Study Of Weight-bearing Hip Stretching Patterns In Patients With Chronic Low Back Pain

Background:Chronic low back pain（CLBP）has been a global disease plaguing human life since the 1990s,with a high disability rate^[1,2].Due to the complex etiology of chronic low back pain,about 85%of them are chronic non-specific low back pain^[1].Traditional rehabilitation therapy,such as physiotherapy and massage,is conducive to the relief of pain,but the curative effect is not lasting.With the development of rehabilitation,it is gradually realized that it is possible to interpret and treat lumbago from the perspective of motor pattern（MT）at the central level and solve the above problems^[3-6].Changes in movement patterns in patients with chronic low back pain have been confirmed by some studies^[7],but few studies have shown that chronic abnormal movement patterns may be responsible for the persistence and recurrence of low back pain.Based on this,this study deeply analyzed the changes of exercise patterns in patients with low back pain by collecting EMG signals.Objectives:To study the changes of hip stretch in weight-bearing position in patients with chronic low back pain by collecting electromyographic signals,to explore the relationship between the changes and low back pain,so as to provide a new assessment idea for analyzing the dysfunction of patients with chronic low back pain and guide clinical treatment.Methods:A case-control study was used.Through inclusion and exclusion criteria,30 healthy subjects and 56 chronic low back pain subjects were selected and divided into healthy group and chronic low back pain group.Three times of hip extension tests were performed in the two groups respectively under weight-bearing position.EMG device was used to collect the EMG signals of bilateral vertical spine muscle,right gluteus maximus muscle and hamstring muscle.The activation order,median frequency and the mean value of EMG were used as the observation indicators to conduct statistical comparison and analysis on the collected data.Results:（1）The sequence of muscle activation in the healthy group was right erector spinal muscle,right hamstring muscle,left erector spinal muscle,and right gluteus maximus muscle;In the chronic low back pain group,the sequence of muscle activation was right hamstring,right erector spinal,left erector spinal,and right gluteus maximus,and the hamstring was overactivated in the initial position.（2）The mean EMG of the left erector spinal muscle,right erector spinal muscle and right hamstring muscle in the healthy group were significantly higher than those in the chronic low back pain group,the difference was statistically significant（P<0.01）;there was no significant difference in right gluteus maximus between the two groups（P=0.281,>0.05）.（3）The MF values of the left erector spinal muscle,right erector spinal muscle and right gluteus maximus in the healthy group were significantly higher than those in the chronic low back pain group,with statistical significance（P<0.01）.Conclusions:Compared with the healthy control group,the muscle recruitment ability of patients with chronic low back pain was significantly reduced,and the muscles of patients with low back pain showed a state of fatigue.In patients with CLBP,the sequence of muscle activation is altered,with hamstring first activated,and compensation of the hamstring during weight-bearing hip extension is generated,suggesting a pattern of exercise that is different from that of healthy people without low back pain.