Influence of Plantar Hardness Discrimination Training on Center-of-Gravity Sway while Standing on One Leg: a Randomized Controlled Trial

Abstract

[Purpose] We investigated the influence of plantar hardness discrimination training on center-of-gravity sway while standing on one-leg. [Subjects] Twenty healthy adult volunteers were randomly divided into intervention (n = 10) and control groups (n = 10). [Methods] The intervention group subjects carried out 10-day plantar hardness discrimination studies on sponges with 5 different levels of hardness. The control group underwent the same training except that they were not instructed to discriminate sponge hardness. Center-of-gravity (COG) sway while standing on one-leg with the eyes open or closed was measured before and after the training. Statistical analyses were performed the COG path length, enveloped area and rectangular area values. [Results] The number of correct answers for hardness discrimination significantly increased with the number of training days. There were significant reductions in the COG path length, enveloped area and rectangular area values after training in the intervention group compared to their respective values prior to training. In contrast, the control group showed no significant changes in these 3 parameters. [Conclusion] Our results suggest that the ability of healthy individuals to regulate center-of-gravity sway while standing on one-leg improved with enhancement of plantar perceptual ability through hardness discrimination training.