Gamma loop dysfunction of the quadriceps femoris of elderly patients hospitalized after fall injury.

Background And Purpose: Gamma loop dysfunction may increase the risk of falls. Therefore, we evaluated gamma loop function in subjects hospitalized after fall injury and examined whether aging affects the gamma loop.

Methods: Maximal voluntary contraction (strength) of knee extension and integrated electromyography (I-EMG) of the quadriceps femoris were examined to evaluate the activities of alpha motoneurons before and after 20-min vibration applied to the quadriceps femoris.