Contribution of arm swing to dynamic stability based on the nonlinear time series analysis method.

It is human nature to swing their arms at the frequency of leg motion during walking, but the contribution of arm swing to dynamic stability of human motion segments was poorly understood. Based on the nonlinear time series analysis method, the objective of this study was to investigate the effects of arm swing in three conditions (natural, active and restricted arm swing) on the dynamic stability of spine and lower extremity joints, and to further assess the contribution of arm swing to the human dynamic stability in relation with age. Gait experiments were carried out for 10 young and 8 middle-aged healthy volunteers while walking with natural, active and restricted arm swing.