title: Fatigue-related changes in fascicle-tendon geometry over repeated contractions: difference between synergist muscles.
abstract: Fatigue-induced changes in force production of synergist muscles were evaluated through observation of fascicle-tendon geometry and electromyography (EMG). Seven subjects performed 60 maximal isometric plantar flexions intermittently. No statistically significant intermuscle difference was observed in the decrease of mean EMG amplitudes or mean power frequency for the medial gastrocnemius (MG) and soleus (SOL) muscles. The tendon elongation of MG significantly decreased after the 19th contraction, and MG fascicle length increased after the 29th contraction, while SOL fascicle and tendon length did not change except for the last contraction. The declines in torques were highly correlated with the increase of MG fascicle length and decrease in tendon elongation in each subject, while no consistent relationship was found for SOL. These results suggest that changes in force-production of MG and SOL over repeated contractions differ, which is reflected in fascicle-tendon geometry.
authors.affiliation: Graduate School of Sport Sciences, Waseda University, Saitama, Japan.
authors.forename: Naotoshi
authors.initials: N
authors.lastname: Mitsukawa
authors.forename: Norihide
authors.initials: N
authors.lastname: Sugisaki
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kanehisa
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Fukunaga
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Kawakami
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D002648:Child; D004576:Electromyography / Q000379:methods; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D053581:Muscle Strength Dynamometer; D018482:Muscle, Skeletal / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology; D013710:Tendons / Q000502:physiology*; D019415:Torque; D055815:Young Adult