title: Interaction between simultaneous contraction and relaxation in different limbs.
abstract: We investigated the interaction between relaxation and contraction for remote, ipsilateral muscles of the hand and foot (wrist extensor/ankle dorsiflexor). Subjects sat in an armchair and were able to freely move their right hand and foot. They performed eight tasks: (1) wrist extension from a flexed (relaxed) position, (2) ankle dorsiflexion from a plantarflexed (relaxed) position, (3) wrist relaxation from an extended position, (4) ankle relaxation from a moderately dorsiflexed position. The remaining tasks involved (5) simultaneous performance of tasks 1 and 2, (6) 3 and 4, (7) 1 and 4, and (8) 2 and 3. Subjects performed each task as fast as possible after hearing a start signal. They were instructed not to activate antagonistic muscles in the tasks involving relaxation. When contraction of the wrist flexor/ankle dorsiflexor was concurrent with relaxation of the ipsilateral limb (ankle dorsiflexor/wrist extensor), the reaction time of contraction as observed in electromyography (EMG) activities in the wrist extensor/ankle dorsiflexor became longer and the EMG activities became smaller. Our findings suggest that muscle relaxation in one limb interferes with smooth movement of muscle contraction in the ipsilateral limb.
authors.affiliation: Graduate School of Sport Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa, Saitama, 359-1192, Japan, kouki-nagoya@fuji.waseda.jp.
authors.forename: Kouki
authors.initials: K
authors.lastname: Kato
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Muraoka
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Higuchi
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Mizuguchi
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Kanosue
mesh_terms: D000328:Adult; D000842:Ankle / Q000502:physiology; D004576:Electromyography / Q000379:methods; D005260:Female; D005528:Foot / Q000502:physiology*; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D009126:Muscle Relaxation / Q000502:physiology*; D014953:Wrist / Q000502:physiology*; D055815:Young Adult