Effects Of Posture Changing And Visual Shielding On Static Balance Control And Lower-limb Muscle Regulation

Objective:By changing the visual feedback and standing posture,the visual and posture to stand the static stability and the influence of the lower limb muscle activity,and from the Angle of nonlinear COP signal and EMG signal processing and analysis,help to deeply explore the mechanism of static balance and adjust strategy,to balance control barriers will provide a scientific basis for treatment and rehabilitation of patients.Methods:24 male college students general,in the three dimensional measuring force platform(Kistler,1000 hz)on normal open,normal close my eyes,both feet stand open and both feet close my eyes,a total of 4 kinds of tasks,in the process of collecting stand plantar pressure center(COP)of mobile trajectory,application methods of wireless power test system(Delsys,2000 HZ)synchronous acquisition tibialis anterior muscle of lower extremities,the lateral head of the gastrocnemius muscle,medial head of the gastrocnemius and soleus,long peroneal muscle,the rectus muscle and stocks of the biceps femoris muscle electromyographic signal.The standard deviation and sample entropy of left and right directions(ML)and front and back directions(AP)of the COP signal were calculated according to the measured COP trajectory coordinates,and the EMG amplitude and self-similarity were calculated using the collected EMG signals.Two-factor repeated-measure ANOVA was used to examine the effects of standing posture and vision on the standard deviation and approximate entropy of left-right forward-back direction of COP signals,as well as the EMG amplitude and selfsimilarity of EMG signals.Pearson correlation was used to analyze the correlation between self-similarity of all lower limbs muscles and the standard deviation and sample entropy of left-right forward-back direction of COP signal,and the significance level was p<0.05.Results:(1)Eliminating visual feedback(closing eyes)and increasing posture difficulty(standing on front and rear feet)significantly increased COP-ML standard deviation(P<0.01);Increasing the difficulty of posture(standing on front and rear feet)significantly increased the standard deviation of COP-AP(P<0.05).(2)The elimination of visual feedback resulted in a decrease in COP-ML sample entropy(P<0.01),whether standing normally or standing on front or rear feet.The COP-ML sample entropy was significantly reduced only when the eyes were opened by increasing the difficulty of the standing posture(standing on the front and rear feet)(P<0.01).(3)The standard deviation and sample entropy of COP-ML showed a strong negative correlation(P<0.01)when standing with eyes open,eyes closed,and feet open,but a weak negative correlation(P>0.05)when standing with eyes closed.In the direction of COP-AP,there was a significant negative correlation between standard deviation and sample entropy regardless of standing condition(P<0.01).(4)During normal standing,eye closing had no effect on the EMG amplitude of lower extremity,but reduced the self-similarity of the medial head of gastrocnemius(P<0.01).(5)when both feet stand,close your eyes cause the tibialis anterior muscle and gastrocnemius,gastrocnemius and soleus,long peroneal muscle,the rectus muscle electricity stocks amplitude increased(p<0.05),at the same time,close your eyes cause,outside of the gastrocnemius muscle,calf,the tibialis anterior muscle rectus muscle and the electromyographic signal of the biceps femoris muscle self-similarity decreased(p<0.05).(6)The electromyoelectric amplitude of tibialis anterior muscle,peroneus longus muscle and rectus femoris muscle were all higher than that of normal standing(P<0.05)when the eyes were open.In addition to the above muscles,the electromyoelectric amplitude of the gastrocnemius muscle,gastrocnemius muscle and soleus muscle were also significantly higher when eyes were closed than when standing normally(P<0.01).(7)The EMG self-similarity of tibialis anterior muscle,gastrocnemius muscle,peroneus longus muscle and rectus femoris muscle were significantly reduced when standing on the front and rear feet,whether the eyes were open or closed(P<0.05).(8)There was a significant negative correlation between the self-similarity of the tibial anterior EMG signal and the standard deviation of COP-ML in normal standing with eyes closed(P<0.05).When standing with eyes closed in front and rear feet,there was a significant positive correlation between self-similarity and COP-ML sample entropy of perfibular longus muscle EMG(P<0.05).Conclusion:(1)Eliminating visual feedback and increasing the difficulty of posture will significantly damage the stability of static standing,and the neuromuscular system will maintain static balance by improving the order and regularity of posture control.(2)Increased active neuromuscular regulation of ankle varus and valgus toe flexion and dorsiflexion contributes to improved standing stability.