Introduction of the vastus medialis oblique H-reflex during traction of the leg

To clarify the excitability of the alpha-motoneuron pool corresponding to the vastus medialis oblique (VMO), this study investigated the H-reflex from the VMO by traction of the leg. One healthy male subject participated in this study, and retesting was performed after 3 days. The surface stimulating electrodes were applied over the course of the femoral nerve on the skin immediately distal to the inguinal ligament. An active electrode for recording the H-reflex was placed on the VMO, and a reference electrode was placed immediately proximal to the patella. The H-reflex was recorded before, during and after traction of the leg. Two patterns of H-reflex modulations were found as follows: 1) the H-reflex amplitudes tended to be lower during traction than before traction, 2) the H-reflex amplitudes tended to be higher after traction. With regard to the decrease in H-reflex amplitude during traction of the leg, the Ib inhibition for the VMO was believed to have occurred by prolonged stretching of the quadriceps tendon and patellar tendon. Also, with regard to the tendency of the VMO H-reflex to increase after traction, disinhibition of the alpha-motoneuron might have occurred in this study.