Quadriceps EMG frequency affected by knee brace during lunge activity in healthy subjects

Abstract

Functional knee braces have been widely (sometimes) used for sports or highly demanding activities in patients with anterior cruciate ligament deficiency. Despite common prescription of the functional knee brace, the mechanism of this action is not clearly understood. The objective of this study was to examine the effect of functional knee braces on muscle activity during lunge motion. Eleven healthy subjects (all male) participated in this study. Electromyography (EMG) of the quadriceps muscle was recorded during lunge motion with and without a custom functional knee brace. EMG frequency analysis was performed in a period of concentric contraction phase and eccentric contraction phase during the lunge. The results of this study showed a decreased high frequency band in the electromyogram during use of the knee brace or an elastic band. Therefore, the inhibition of the fast muscle fibers was thought to a possible reason for muscle atrophy with the knee brace.