Foot position awareness in younger and older men: the influence of footwear sole properties.

Objectives: To test the hypotheses that foot position awareness is related positively to stability, positively to shoe sole hardness, and negatively to shoe sole thickness, and that foot position awareness declines with advancing years.

Setting: Older subjects were consecutive volunteers from a medical clinic; younger subjects were volunteers from the community.

Design: Randomized-order, cross-over, controlled comparison.

Participants: Older subjects were a random sample of 13 healthy men, mean age 72.58 years, SD +/- 4.50. Younger subjects were a random sample of 13 male subjects from the general population, mean age 28.13 years, SD +/- 3.96. Additional selection criteria were absence of disabilities influencing ability to walk and no history of frequent falls.

Measurements: Balance failure frequency, defined as falls per 100 meters of beam walking; rearfoot angle in degrees, measured via an optical position measurement system; perceived maximum supination when walking, in degrees, estimated by subjects using a ratio scale; foot position error, in degrees, was defined as the rearfoot angle minus perceived maximum supination.

Results: Foot position error during walking: (1) increases with advancing years; footwear conditions absolute mean error for older sample of 15.48 degrees, SE +/- 1.56 degrees, and younger sample 5.44 degrees, SE +/- 1.03 degrees (P > .001); (2) is positively related to stability (r = .367, P < .001); (3) is positively related to midsole thickness (F(1,11) = 19.89, P < .001); (4) is negatively related to midsole hardness (F(2,22) = 29.80, P < .001); (5) correlates best with perceived maximum supination (r = .901, P < .001).

Conclusion: Foot position awareness is related causally to stability; shoes with thin, hard soles provide better stability for men than those with thick, soft midsoles. Foot position awareness declines with advancing years.