Evaluation of sit-to-stand motion using a pressure distribution measurement system--effect of differences in seat hardness on sit-to-stand motion.

PURPOSE: This study examined differences between standing from an ordinary seat and standing from a low-repulsion mat using a pressure distribution measurement system (BIG-MAT) and identified parameters to determine sit-to-stand (STS) motion difficulty. METHOD: Ten healthy male volunteers (aged 30-38 years) participated. During STS motion from an ordinary seat and from a low-repulsion urethane mat, plantar surface pressure changes of both feet and the centre of pressure (COP) trajectory were recorded for 7 s. This series of tests was performed four times in each subject. Left and right pressure changes and COP changes were evaluated. Differences in the measurements between the low-repulsion mat and the ordinary seat were compared using the paired t-test. RESULTS: COP changes were similar to those previously reported. Time from hindfoot peak to forefoot peak was significantly shorter with the ordinary chair than with the mat (p < 0.05). Percent change in forefoot pressure at forefoot peak and hindfoot peak (p < 0.01) and percent change in forefoot pressure at forefoot peak and stabilisation (p < 0.05) were significantly different. CONCLUSIONS: Time from hindfoot peak to forefoot peak and percent change in forefoot pressure at forefoot peak and hindfoot peak were the best indicators of STS motion difficulty.