title: Length change of human gastrocnemius aponeurosis and tendon during passive joint motion.
abstract: The extent of elongation and slackness of aponeurosis and tendon, and muscle fiber length of human medial gastrocnemius muscle are determined in vivo using ultrasonography. The ankle joint is passively moved at 5 degrees /s within the joint range of -36 to 7 degrees (0 degrees = neutral anatomic position; positive values for dorsiflexion) by a dynamometer while the length change of the aponeurosis and tendon is determined using ultrasonography (n = 8 men). Strain is calculated as the length change relative to the reference length of aponeurosis and tendon when the passive joint moment is 0. Elongation (positive strain values) of aponeurosis and tendon at 7 degrees are 2.1 +/- 1.1 and 2.4 +/- 1.0%, respectively. The extent of slackness (negative strain values) of aponeurosis and tendon at -36 degrees are -1.8 +/- 1.1 and -3.5 +/- 1.6%, respectively, and there is a significant difference between them (p < 0.05). This may be related to the existence of muscle fibers that attach to the aponeurosis over its whole length and do not allow it to fold. The results indicate that the length change of aponeurosis and tendon of medial gastrocnemius muscle occurs over the range of ankle joint positions even during passive joint motions.
authors.affiliation: Laboratory of Sports Sciences, Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Japan. cc97726@mail.ecc.u-tokyo.ac.jp
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Muraoka
authors.forename: Tadashi
authors.initials: T
authors.lastname: Muramatsu
authors.forename: Daisuke
authors.initials: D
authors.lastname: Takeshita
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kawakami
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Fukunaga
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000000981:diagnostic imaging / Q000502:physiology; D018482:Muscle, Skeletal / Q000166:cytology / Q000000981:diagnostic imaging / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D013710:Tendons / Q000166:cytology / Q000000981:diagnostic imaging / Q000502:physiology*; D014463:Ultrasonography