title: In vivo fascicle behavior of synergistic muscles in concentric and eccentric plantar flexions in humans.
abstract: 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.
authors.affiliation: Japan Institute of Sports Sciences, Kita-ku, Tokyo, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Chino
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Oda
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Kurihara
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Nagayoshi
authors.forename: Kohki
authors.initials: K
authors.lastname: Yoshikawa
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: D000125:Achilles Tendon / Q000502:physiology*; D000328:Adult; D000704:Analysis of Variance; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D004548:Elasticity; D004576:Electromyography / Q000379:methods; D006801:Humans; D007700:Kinetics; D008297:Male; D009068:Movement / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000502:physiology*; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D013997:Time Factors; D014463:Ultrasonography