Standing postural control after cooling of sole and crural muscles - Comparisons of muscle activities and lengths of center of gravity sway on static and dynamic postural control with eyes closed

The purpose of this study was to examine what sole sensory or crural muscle proprioception contributes to standing postural control. The subject were 12 healthy young adult males. Each had their sole and crus cooled The integrated electromyographic values (iEMGs) of trunk and leg muscles and locus lengths of center of gravity (COGs) were compared among before cooling (control), 0-3min after cooling and with a skin temperature more than 20°C higher under static standing with eyes closed and dynamic standing with eyes closed conditions. The iEMG ratios of trunk and proximal leg muscles after sole cooling increased significantly compared to the control. The locus lengths of COGs after sole cooling also extended significantly compared to the control. From the results, we concluded that diminuition of sole mechanoreceptor signals shifted from ankle strategy to hip strategy and diminuition of crural muscle proprioceptive signals, and extension of locus lengths of COGs also occurred. Consequently, we consider that the deterioration of standing postural control was elicited by decline of sole mechanoreceptor signals rather than that of crural muscle proprioceptive signals.