title: The influence of fascicle behavior on the lack of velocity dependence in eccentric joint torque in humans: in vivo observation.
abstract: To investigate the relationship between fascicle behavior and joint torque, the fascicle behavior of the triceps surae during isometric and eccentric (30 and 60 deg/s) plantar flexion by maximal voluntary and submaximal electrical activation (MVA and SEA) was measured by realtime ultrasonography. Eccentric torque at 30 and 60 deg/s was significantly higher than isometric torque under SEA, but not under MVA. However, fascicle length did not significantly differ between isometric and eccentric trials under either condition. Therefore, the difference in developed torque by MVA and SEA cannot be explained by fascicle behavior. Under both MVA and SEA conditions, eccentric torque at 30 and 60 deg/s was equivalent. Similarly, fascicle lengthening velocities at 30 and 60deg/s did not show any significant difference. Such fascicle behavior can be attributed to the influence of tendinous tissue and pennation angle, and lead to a lack of increase in eccentric torque with increasing angular velocity.
authors.affiliation: Japan Institute of Sports Sciences, Tokyo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Chino
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Mitsukawa
authors.forename: Kai
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Miyoshi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Oda
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kanehisa
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Fukunaga
authors.forename: Senshi
authors.initials: S
authors.lastname: Fukashiro
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kawakami
mesh_terms: D000843:Ankle Joint / Q000502:physiology*; D003198:Computer Simulation; D006801:Humans; D008297:Male; D008954:Models, Biological; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D019415:Torque; D055815:Young Adult