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

Hiroshi Akima, Akira Saito

Research output: Contribution to journalArticle

22 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)682-690
Number of pages9
JournalMuscle and Nerve
Issue number5
Publication statusPublished - 2013 May
Externally publishedYes



  • Concentric contraction
  • Eccentric contraction
  • EMG-angle relationship
  • Quadriceps femoris
  • Surface electromyogram

ASJC Scopus subject areas

  • Clinical Neurology
  • Cellular and Molecular Neuroscience
  • Physiology (medical)
  • Physiology

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