Changes in arm posture during the early acquisition of walking

Changes in arm posture and movement of the arms in relation to step width w ere studied longitudinally for 4 to 6 months in 6 infants who had just begu n to walk. Arm postures and movements were coded from video recording and s tep width was calculated from force platform data. The results showed that arms were held in fixed postures during the first 10 weeks. A decrease in t hese fixed postures was correlated with a decrease in step width. The emerg ence of arm movement occurred when balance control improved. The hypothesis that arm postures fulfill the dual task of stabilizing the body in an upri ght posture while moving it forward is discussed. (C) 2000 Elsevier Science Inc. All rights reserved.