Visual push: a sensitive measure of dynamic balance in man.

Forty-six subjects aged 17 to 79 years who had not fallen in the previous year were exposed to an illusory visual stimulus while they stood on a force platform, with or without the introduction of a polyurethane foam pad under their feet to reduce proprioception. The amplitude of sway obtained in this way was not correlated to age, but the sway path in the anteroposterior plane increased logarithmically with increase in age. The method proved to be more sensitive than similar measures obtained without the illusory visual stimulus.