Comparion of Standing Posture Control between Pre and Post Head out Water Immersion

The effects of autonomic nervous system by head-out water immersion at thermoneutral temperature will also influence the standing posture control. This study aimed to compare variations in posture control ability after standing from the water immersion at thermoneutral temperatures for healthy young Japanese adults. The healthy male college students (n=5) participated in this study. The body composition of the subjects was measured by bio-impedance method. Postural sway was recorded by detecting the body’s center of gravity continuously with a force platform equipped with a data processor. The body sway of each subject was recorded for 1min, first with the eyes open (EO) and next with eyes closed (EC). During each task, the foot center of pressure (COP) position and horizontal ground reaction force were measured. Power spectra of body sway were evaluated by comparing powers in tow frequency bands: 0.02–1.0 (BAND 1), 1.0–10.0 Hz (BAND 2). There was no significant difference between pre and post water immersion of COP in EO and EC. However, quiet standing posture sway in the medio-lateral axes tended to be lower post water immersion in both BAND 1 and BAND 2 in the EC condition. It was only a tendency to decrease in the BAND 2 in posture sway of medio-lateral axes. These results suggest that lower leg muscles to relax by water immersion can be maintained a stable standing posture in human. This was suggested to be due to inhibition of somatosensory by water immersion.