Neuromuscular Activation of the Vastus Intermedius Muscle during Isometric Hip Flexion

Abstract

Although activity of the rectus femoris (RF) differs from that of the other synergists in quadriceps femoris muscle group during physical activities in humans, it has been suggested that the activation pattern of the vastus intermedius (VI) is similar to that of the RF. The purpose of present study was to examine activation of the VI during isometric hip flexion. Ten healthy men performed isometric hip flexion contractions at 25%, 50%, 75%, and 100% of maximal voluntary contraction at hip joint angles of 90°, 110° and 130°. Surface electromyography (EMG) was used to record activity of the four quadriceps femoris muscles and EMG signals were root mean square processed and normalized to EMG amplitude during an isometric knee extension with maximal voluntary contraction. The normalized EMG was significantly higher for the VI than for the vastus medialis during hip flexion at 100% of maximal voluntary contraction at hip joint angles of 110° and 130° (P < 0.05). The onset of VI activation was 230–240 ms later than the onset of RF activation during hip flexion at each hip joint angle, which was significantly later than during knee extension at 100% of maximal voluntary contraction (P < 0.05). These results suggest that the VI is activated later than the RF during hip flexion. Activity of the VI during hip flexion might contribute to stabilize the knee joint as an antagonist and might help to smooth knee joint motion, such as in the transition from hip flexion to knee extension during walking, running and pedaling.

Bilateral Comparisons of Quadriceps Thickness after Anterior Cruciate Ligament Reconstruction

“…A study reported that a smaller VI thickness was associated with the knee extension torque, which is related to the performance of explosive movements [ 13 ]. In addition, another study showed that the VI is activated during the recovery phase of running, which could indicate that it provides knee joint stabilization as an antagonist during hip flexion [ 35 ]. A study with patients who had undergone ACLR showed VI thickness reduction to result in decreased knee extension torque and the same study suggested that increasing VI thickness by rehabilitation after ACLR could be the key factor for the proper restoration of knee function [ 36 ].…”

Structural diversity of the vastus intermedius origin revealed by analysis of isolated muscle specimens

“…Recent investigators have tried to measure the electromyographic activity of the VI by surface and needle electrodes, on the assumption that the inferolateral part of the QF would represent the VI as suggested by magnetic resonance imaging (Watanabe and Akima, 2009;Saito and Akima, 2015;Tomita et al, 2015). However, this study revealed beyond doubt that this muscular part represented the VL-O, not the VI.…”

Effects of Joint Assistance on the Muscle Metabolism and Strength in Different States Based on Simulation

“…Hip flexion assistance could release pressure of hip flexion muscle groups and decrease the strength of the short head of biceps femoris arisen from the lateral lip of the linea aspera. Hip extension assistance descended the strength of vastus intermedius which had a closer route for the excitatory impulse on α-motoneuron of the vastus intermedius than other knee muscle groups, making vastus intermedius more sensitive to external stimulus [54,55]. As for knee flexion assistance, the strength of the short head of the biceps femoris dropped and the strength of vastus intermedius fell conspicuously.…”