Longitudinal and transverse deformation of human Achilles tendon induced by isometric plantar flexion at different intensities

Soichiro Iwanuma, Ryota Akagi, Toshiyuki Kurihara, Shigeki Ikegawa, Hiroaki Kanehisa, Tetsuo Fukunaga, Yasuo Kawakami*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


The present study determined in vivo deformation of the entire Achilles tendon in the longitudinal and transverse directions during isometric plantar flexions. Twelve young women and men performed isometric plantar flexions at 0% (rest), 30%, and 60% of the maximal voluntary contraction (MVC) while a series of oblique longitudinal and cross-sectional magnetic resonance (MR) images of the Achilles tendon were taken. At the distal end of the soleus muscle belly, the Achilles tendon was divided into the aponeurotic (ATapo) and the tendinous (ATten) components. The length of each component was measured in the MR images. The widths of the Achilles tendon were determined at 10 regions along ATapo and at four regions along ATten. Longitudinal and transverse strains were calculated as changes in relative length and width compared with those at rest. The ATapo deformed in both longitudinal and transverse directions at 30%MVC and 60%MVC. There was no difference between the strains of the ATapo at 30%MVC and 60%MVC either in the longitudinal (1.1 and 1.6%) or transverse (5.0∼11.4 and 5.0∼13.9%) direction. The ATten was elongated longitudinally β.3%) to a greater amount than ATapo, while narrowing transversely in the most distal region (-4.6%). The current results show that the magnitude and the direction of contraction-induced deformation of Achilles tendon are different for the proximal and distal components. This may be related to the different functions of Achilles tendon, i.e., force transmission or elastic energy storage during muscle contractions.

Original languageEnglish
Pages (from-to)1615-1621
Number of pages7
JournalJournal of Applied Physiology
Issue number6
Publication statusPublished - 2011 Jun


  • In vivo
  • Magnetic resonance imaging
  • Strain distribution

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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