AN ELECTROMYOGRAPHIC ANALYSIS OF THE KNEE DURING FUNCTIONAL ACTIVITIES .1. THE NORMAL PROFILE

This study describes the fine-wire electromyographic profile of the no rmal knee. Twenty-two subjects with no prior history of knee injury vo lunteered for the study. Each subject had fine-wire electromyographic evaluation of 8 muscles (vastus medialis oblique, vastus lateralis, re ctus femoris, semimembranosus, biceps femoris, tibialis anterior, gast rocnemius, and soleus muscles) while performing 7 functional activitie s. The percentage of maximum manual test for each muscle during each p hase of the activities was used to determine means and standard deviat ions for the group. Walking and ramp and stair ascending and descendin g produced similar electromyographic profiles. Running and cross-cutti ng demonstrated unique electromyographic profiles with an overall high er muscle activity than the previous 5 activities. A quadriceps-hamstr ings muscles' coordinated response was identified consistently in each activity. These findings illustrate the integral nature of each of th e 8 examined muscles in knee motion. Furthermore, this study demonstra tes a coordinated response of quadriceps-hamstrings muscles in the nor mal knee and may more thoroughly define the coordinated activity of th ese 2 antagonist muscle groups. Finally, this study provides a framewo rk within which various knee conditions can be compared and from which specific rehabilitation recommendations can be generated.