Hiroshi Akima1, Akira Saito. 1. Research Center of Health, Physical Fitness & Sports, Nagoya University, Furo, Chikusa, Nagoya, Aichi 4648601, Japan. 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.
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.
Authors: Jae-Ho Yang; Seung-Pyo Eun; Dong-Ho Park; Hyo-Bum Kwak; Eunwook Chang Journal: Int J Environ Res Public Health Date: 2019-12-04 Impact factor: 3.390