Effect of series elasticity on isokinetic torque-angle relationship in humans |
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Authors: | Kawakami Y Kubo K Kanehisa H Fukunaga T |
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Institution: | (1) Department of Life Sciences (Sports Sciences), Graduate School of Arts and Sciences, University of Tokyo, Komaba, Komaba 3-8-1, Meguro, Tokyo 153-8902, Japan, |
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Abstract: | 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.
Electronic Publication |
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Keywords: | Knee extension Isometric and isokinetic contractions Vastus lateralis muscle Ultrasound Tendinous tissues |
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