In vivo fascicle behavior of synergistic muscles in concentric and eccentric plantar flexions in humans

Kentaro Chino, Toshiaki Oda, Toshiyuki Kurihara, Toshihiko Nagayoshi, Kohki Yoshikawa, Hiroaki Kanehisa, Tetsuo Fukunaga, Senshi Fukashiro, Yasuo Kawakami*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)


Ultrasonography was used to directly measure in vivo fascicle behavior of the medial gastrocnemius (MG) and soleus (SOL) muscles while the subjects (n = 6 men) performed maximal voluntary concentric and eccentric plantar flexions at 60, 120, 180 and 240 deg/s. Fascicle shortening and lengthening velocities of MG, obtained from fascicle length changes over time, were significantly higher than those of SOL at ±120, ± 180 and +240 deg/s, possibly reflecting physiological and mechanical differences between these muscles. On the other hand, the effective fascicle shortening and lengthening velocities, defined as the velocities in the longitudinal direction of muscle belly, were not significantly different between MG and SOL. This could be due to difference in fascicle architecture and/or the existence of mechanical linkages between these muscles. Moreover, when the contribution of tendinous tissues to muscle-tendon complex length change was determined from fascicle length, pennation angle, moment arm and joint angle, it accounted for approximately 50% in both concentric and eccentric trials, but showed considerable intra-subject variations. This result quantifiably demonstrates the importance of tendinous tissues in isokinetically controlled joint movements.

Original languageEnglish
Pages (from-to)79-88
Number of pages10
JournalJournal of Electromyography and Kinesiology
Issue number1
Publication statusPublished - 2008 Feb


  • Gastrocnemius and soleus muscles
  • Isokinetic joint movement
  • Muscle-tendon complex
  • Tendinous tissues

ASJC Scopus subject areas

  • Neuroscience (miscellaneous)
  • Biophysics
  • Clinical Neurology


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