Resonance in the human medial gastrocnemius muscle during cyclic ankle bending exercise

Daisuke Takeshita, Akira Shibayama, Tetsuro Muraoka, Tadashi Muramatsu, Akinori Nagano, Tetsuo Fukunaga, Senshi Fukashiro

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


We investigated the behavior of the muscle tendon unit (MTU) of the medial gastrocnemius muscle during cyclic ankle bending exercise at eight different frequencies (ranging from 1.33 to 3.67 Hz). The changes in the length of fascicle in the muscle during the exercises were determined by real-time ultrasound imaging. The coordinates of anatomical references and the ground reaction force were determined from video recording and a force plate, respectively. The length change of the MTU (the distance from the origin to insertion of the muscle) was calculated from changes in the knee and ankle joint angles. It was found that the amplitude ratio and phase difference between the fascicle and MTU lengths were both dependent on the movement frequency. At lower frequencies, the fascicle lengths varied almost in phase with the MTU length, whereas they varied out of phase at the higher frequencies. At intermediate frequency, the amplitude of the fascicle became very small compared with that of the MTU, which is considered resonance. We constructed a mechanical model of the MTU based on a notion of forced oscillation in a mass-spring system. The obtained data were well explained by the model. It was concluded that the behavior of the MTU highly depends on the movement frequency due to the viscoelasticity of the MTU.

Original languageEnglish
Pages (from-to)111-118
Number of pages8
JournalJournal of Applied Physiology
Issue number1
Publication statusPublished - 2006


  • Muscle mechanism
  • Tendinous tissue
  • Ultrasound imaging
  • Viscoelasticity

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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