Lower extremity muscle coordination in stroke patients revealed by surface electromyography / 中华物理医学与康复杂志

Objective To explore the changes in muscle activity patterns in the lower leg during ankle dorsiflexion and plantarflexion in stroke patients. Methods Ten recovering stroke patients with hemiparesis(Pa- tient group)and ten age-and sex-matched healthy volunteers(Healthy control group)were studied.The subjects performed ankle dorsiflexion and plantarflexion synchronized with a visual cue while supine.Surface electrodes were applied over the anterior tibialis(TA),caput laterale musculi gastrocnemius(IGM),caput mediale musculi gas-troenemius(mGM)and soleus muscles(SOL)for integrated electromyography(iEMG).Results During ankle dorsiflexion,the TA,lGM,mGM and SOL of the affected side showed a significantly lower iEMG signal than the unaffected side.Activity of the lGM,mGM and SOL of the affected side were significantly lower than in the healthy controls.During ankle plantaflexion,the TA,lGM and mGM on the affected side had significantly lower activity than those of the healthy controls.The mGM of the affected side showed significantly lower muscle activity than the unaffeeted side.The SOL contraction ratio on the affected side was significantly higher than on the unaffected side and in the healthy control group. Conclusion Except for the soleus,there is an obvious decline in muscle activi-ty in the affected lower extremities of stoke patients during ankle dorsiflexion and plantaflexion.The soleus on the affected side becomes the primary plantarflexor in patients with stroke,rather than the caput laterale musculi gas-trocnemius or caput mediale musculi gastroenemius as in healthy subjects.

Electromyogram patterns during ankle joint movements at various angular velocities in the triceps surae muscles / 体力科学

Surface electromyograms (EMGs) were recorded from the triceps surae muscles in order to examine muscle activities during concentric and eccentric ankle joint movements at various angular velocities under constant load (5 and 10%MVC) . The results were summarized as follows ;<BR>1) At slow angular velocity (6 deg/s) of ankle joint movement, EMG amplitude tended to increase at a larger ankle joint angle in the gastrocnemius muscle, and at a smaller angle in the soleus muscle.<BR>2) Following an increase in angular velocities (6→30→60 deg/s), peak values of integrated EMGs were significantly increased (7-15%) in the medial gastrocnemius muscle. However, these peak values were significantly decreased in the soleus muscle (22-49%) . These results suggest selective recruitment of motor units depending on angular velocity.<BR>3) Ankle joint angle at the peak integrated EMGs was significantly increased following an increase in angular velocity (6→30→60 deg/s) in the soleus muscle. This suggests that the angle at the recruitment of motor units may be dependent on angular velocity in the soleus muscle.