Background: People with the knee osteoarthritis (OA) might change their kinematic and kinetic patterns as a compensatory mechanism possibly to decrease pain during movement. These alterations in movement pattern might contribute towards weakness of the involved muscle groups such as the quadriceps muscle group. The aim of this study was to evaluate the surface electromyography (SEMG) of the quadriceps of people with the knee OA during ascending and descending in stairs with different heights.
Methods: Fourteen female patients with the knee OA aged between of 50 to 75 years, participated in this study. Electromyography of three muscles including rectus femoris, vastus medialis and vastus lateralis were collected using a 16-channel ME6000 EMG system when participants ascended and descended a set of stairs with heights of 15, 19, 23 cm. The recorded signals were band pass filtered, their root mean square (RMS) was calculated, and was compared between different conditions.
Results: The activity of muscle during ascending the stairs was higher than descending (p <0.05). Reduced activity was observed in the swing step (the second step) than the stance step (the first step) (p <0.05).
Conclusion: The results of the study revealed the differences of thre muscles of quadriceps act during stair ascending and descending in stairs with different heights.