Controlling swing foot center of mass and toe trajectory to minimize tripping risk.

Swing toe trajectory has been investigated due to its association with tripping-induced falls. This study investigated how motion of the entire foot segment influences the toe trajectory. Seven young and seven older participants walked both over-ground and on a treadmill to obtain the swing foot trajectory data. No ageing effects were obtained for toe trajectory control. Older adults were found to have greater asymmetry at minimum ground clearance, especially in treadmill walking, whereas foot center of mass (COM) control was symmetrical, suggesting that foot COM motion does not influence toe trajectory. Correlation analysis indicated that foot COM and toe trajectory may be controlled independently due to ankle motions that modulate the toe's elevation, a finding that has implications for falls prevention strategies. The results also provide the first report of the foot's center of mass trajectory during the swing phase of the gait cycle. The foot's trajectory resembles pendulum motion but further work will be necessary to test the foot-pendulum control hypothesis.