The timing of muscle activation in walking after a stroke / 中华物理医学与康复杂志

ABSTRACT

Objective To observe among stroke survivors the timing of muscle activation at the stance phase during walking using the surface electromyography ( sEMG) combined with 3D gait analysis. Methods Twenty stroke survivors assessed as at Brunnstrom stages Ⅲ, Ⅳ and Ⅴ were assigned to groups designated Ⅲ, Ⅳ and V. sEMG and 3D gait analysis were used to assess the activation timing of the bilateral rectus femoris ( RF) and biceps femoris ( BF) , the tibialis anterior ( TA) and the gastrocnemius medialis ( GM) . The activation timing and the dura-tion of activation of the muscles were compared among the 3 groups, as well as with those of healthy muscles. Results The onset time of the RF on the affected side was significantly later than on the healthy side, while that of the GM was significant earlier. The durations of BF and GM activation on the affected side were significantly shorter than on the unaffected side in group III. The onset times of the TA and GM on the affected side were significantly ear-lier than on the healthy side in group IV, as was the onset time of the TA of the affected side in group V. The average RF and BF onset times on the affected side in group Ⅳ were significantly earlier than in group Ⅲ. The onset time of the TA on the unaffected side and the average BF onset time on the affected side in group Ⅴ were significantly later than in group IV. The onset time of the RF and TA on the unaffected side in group Ⅳ and the onset time of the GM on the affected side were significantly later than in group III, while the onset time of the BF and TA on the affected side was significantly earlier. The average duration of BF activation on the unaffected side in group Ⅳ was significant-ly shorter than that of group Ⅲ. The average duration of TA activation on the unaffected side in group Ⅴ was signifi-cantly shorter than that of group IV. The duration of RF activation on the affected side in group Ⅴ was significantly shorter than that in group Ⅲ, and the same was true of the RF, BF, TA and GM activation times on the healthy side. Conclusions There are significant differences in the onset and duration of muscle activation when stroke survivors at different stages of recovery walk. Some muscles are activated too early and others are over-activated. These abnormali-ties gradually disappear with the recovery of motor function.