Effect of series elasticity on isokinetic torque-angle relationship in humans

Y. Kawakami*, K. Kubo, H. Kanehisa, T. Fukunaga

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

36 Citations (Scopus)


The influence of muscle series elasticity on the relationship between torque and joint angle during dynamic contractions was studied. The torque-angle relationship during the maximal isokinetic knee extension was determined for six male subjects (25-45 years) at 0.52, 1.05, 1.57, 2.09, 2.62, 3.49 rad/s. The knee joint angle at which peak torque was observed showed a systematic shift to more extended positions, i.e., the quadriceps muscle-tendon unit length became shorter as the velocity increased [from 1.01 (0.12) rad (0.52 rad/s) to 0.75 (0.14) rad (3.49 rad/s), mean (SD)]. The corresponding difference in muscle-tendon unit length between 0.52 and 3.49 rad/s, estimated from the angle shift at peak torque and the moment arm length change of the quadriceps muscles, was 9 (4) mm. The relationship between estimated changes in muscle-tendon unit length and muscle force of the vastus lateralis and intermedius (VLI) over the seven velocities (including isometric contraction, 0 rad/s) coincided with the load-elongation properties of the series elastic component of VLI, determined separately in vivo by ultrasonography when the same subjects performed a ramp isometric knee extension. The results suggest that the torque-angle relationship is affected by the interaction between contractile and elastic components, and that peak torque angle shift is attributable to the elongation of tendinous tissues as a function of force applied to them.

Original languageEnglish
Pages (from-to)381-387
Number of pages7
JournalEuropean Journal of Applied Physiology
Issue number4-5
Publication statusPublished - 2002
Externally publishedYes


  • Isometric and isokinetic contractions
  • Knee extension
  • Tendinous tissues
  • Ultrasound
  • Vastus lateralis muscle

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Public Health, Environmental and Occupational Health
  • Physiology (medical)


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