Regional variation and changes with ageing in vibrotactile sensitivity in the human footsole.

Recently there has been indirect evidence suggesting that age-related elevation in footsole vibration detection may be associated with balance and gait dysfunction. As a first step in investigating this dysfunction, the current study determined by how much plantar vibration sensation decreases as a function of age, and if change is dependent on frequency and location of vibration application. Vibration thresholds were assessed at 4 frequencies (25-400 Hz), at 55 locations, and in young and older participants. Results showed there were 3 regions of sensitivity on the footsole: the ball/medial arch, the lateral border of the foot and heel, and the toes. Thresholds for fast-adapting type I receptor (FAI)-mediated frequencies were age invariant; however, thresholds for fast-adapting type II receptor (FAII)-mediated frequencies increased with age. These changes may be one of many factors contributing to age-related changes in gait.