Short term alteration of balance control after a reduction of plantar mechanoreceptor sensation through cooling

Proprioceptive inputs from the plantar sole contribute to balance control during normal quiet standing. This study investigated the cooling of plantar sole mechanoreceptors through ice immersion and its effects on balance control and lower leg muscle activity. Ten healthy males participated in this study. Plantar sole sensitivity was tested using the two point discriminatory test and the Von Frey monofilaments test. Plantar sole cooling was achieved through foot immersion in ice water. Balance control was measured using a force platform with seven trials (30 s) performed before and after ice water foot immersion. Lower limb balance control muscle activity was measured with electromyography. Ice cooling reduced the plantar sole sensitivity of the foot. A short term alteration in balance control was observed with only the first trial showing significantly greater speed and RMS of the velocity of the centre of pressure in the cooling condition when compared to control trials before cooling. Muscular activity increased following the first trial. The adaptation observed after the short term alteration of balance control, could result from sensory reweighting processes. It is suggested that the muscular activity increase is evidence of sensory reweighting and contributes to the regulation of balance control when the plantar sole sensation is partially inhibited. (C) 2012 Elsevier Ireland Ltd. All rights reserved.