Lower limb muscle activation during the sit-to-stand task in subjects who have had a stroke

Objective: The aim of this study was to compare electromyographic activities between and within the paretic and nonparetic lower limb muscles during the sit-tostand (STS) task in subjects with hemiparesis as a result of stroke. Design: This is a cross-sectional study. Results: All monitored muscles of both lower limbs remained active during most of the sit-to-stand task; the muscles were activated before the seat-off and reached the maximum peak of electromyographic activity after the seat-off (P < 0.01). As compared with the paretic limb, the nonparetic limb exhibited earlier activation of the hamstrings (P < 0.01); longer activation period (P < 0.01); and higher electromyographic activity of the tibialis anterior, the soleus, and the quadriceps (P e 0.02). The activity onset time was similar in all muscles of the nonparetic lower limb (P ≥ 0.053), whereas the tibialis anterior of the paretic lower limb was activated before the hamstring and the soleus (P ≤ 0.015). These results illustrate that muscle activation of both limbs during the sit-to-stand task was impaired but in a higher level in the paretic side. Conclusions: Neuromuscular coordination abnormalities were observed in both lower limbs. The paretic limb was unable to recruit the muscles at the proper time and to achieve the amplitude for executing the sit-to-stand task, whereas significant compensations occurred on the nonparetic side.