Inverse activation between the deeper vastus intermedius and superficial muscles in the quadriceps during dynamic knee extensions

Authors

  • Hiroshi Akima PhD,

    Corresponding author
    1. Graduate School of Education and Human Development, Nagoya University, Nagoya, Japan
    • Research Center of Health, Physical Fitness & Sports, Nagoya University, Furo, Chikusa, Nagoya, Japan
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  • Akira Saito MEd

    1. Graduate School of Education and Human Development, Nagoya University, Nagoya, Japan
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Correspondence to: H. Akima; E-mail: akima@nagoya-u.jp

Abstract

Introduction: We sought to determine the neuromuscular activation patterns of 4 synergistic muscles of the quadriceps femoris (QF), including the vastus intermedius (VI) muscle, during dynamic knee extensions. Methods: Nine healthy men performed dynamic knee extensions in the range of 20–100% of the one-repetition maximum (1RM) load. Surface electromyography (EMG) was recorded from the 4 muscles of the QF. Results: The normalized EMG amplitude of the VI was significantly higher at knee joint angles between 90° and 115° during both the concentric and eccentric phases, and it was significantly lower between 140° and 165° during concentric and eccentric phases, compared with those of vastus lateralis at 60–100% of 1RM load (P < 0.05). Conclusions: These results suggest that the VI plays a key role during dynamic knee extension with flexed joint angles and specifically contributes to the initial concentric and final eccentric phases of knee joint movements. Muscle Nerve 47: 682–690, 2013

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