Proprioception and stability: foot position awareness as a function of age and footwear.

We examined the hypothesis that awareness of foot position in terms of the slope of the weight-bearing surface declines with age. We further postulated that the decline would be due to a change in plantar tactile sensibility, and that footwear would further impair position judgments. We compared 15 men aged over 65 years (mean age 73) with 36 men aged under 40 (mean age 30) in terms of estimates of amplitude and direction of surface slopes. We employed a ratio scale of 0-10 representing actual slopes of 0 degrees-25 degrees in increments of 2.5 degrees. In order to examine whether subjects overestimated high angles they were told that the scale ranged from 0 to 15. We found significant differences between the two groups in terms of estimates and the effect of footwear. Psychophysical functions for estimate of slope were 0.95 for the young when barefoot and 0.71 when shod compared with 0.80 and 0.81 respectively for the older men. We conclude that sensitivity to foot position declines with age, mainly owing to loss of plantar tactile sensitivity. Footwear impairs foot position awareness in both young and old. Loss of foot position awareness may contribute to the frequency of falls in later life.