title: Effects of stance width on postural movement pattern and anticipatory postural control associated with unilateral arm abduction.
abstract: We investigated the effects of stance width on postural movement pattern and activation timing of postural muscles during unilateral arm abduction. Thirty-two healthy subjects abducted the right arm at their own timing. Stance width was 0, 9, 18 or 27 cm. Movement angles of leg lateral inclination and trunk lateral flexion to the leg in the frontal plane were analyzed. Based on movement angles at 0 cm width, subjects were classified into three groups: contralateral whole body leaning (CWBLg); ipsilateral trunk flexion (ITFg); and contralateral trunk flexion (CTFg). A high correlation between the movement angles was obtained at 0 cm width (r=0.82). With increasing stance width, postural movement pattern in the ITFg shifted to patterns characterized by lateral flexion of the trunk toward the side opposite to arm movement, and movement angle of leg-inclination in ITFg and CWBLg decreased. At 0 cm width, left gluteus medius and tensor fascia latae were activated significantly about 40 ms ahead of the right middle deltoid in CWBLg and CTFg, but not in ITFg. However, preceding activation became prominent (about 20 ms) in ITFg for wide stances. Moreover, bilateral activation of the tensor fascia latae was observed in CTFg for all widths.
authors.affiliation: Department of Human Movement and Health, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-8640, Japan. fujikatu@med.kanazawa-u.ac.jp
authors.forename: Katsuo
authors.initials: K
authors.lastname: Fujiwara
authors.forename: Hidehito
authors.initials: H
authors.lastname: Tomita
authors.forename: Nozomi
authors.initials: N
authors.lastname: Kurokawa
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Asai
authors.forename: Kaoru
authors.initials: K
authors.lastname: Maeda
mesh_terms: D000328:Adult; D001132:Arm / Q000502:physiology*; D001288:Attention / Q000502:physiology*; D005246:Feedback / Q000502:physiology; D005260:Female; D006801:Humans; D019545:Intuition / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D004856:Postural Balance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D055815:Young Adult