Sex and age differences of relationships among stepping parameters for evaluating dynamic balance in the elderly.

This study aimed to examine the relationships among various stepping parameters, sex, and age in the elderly. Healthy elderly Japanese individuals 60-85 years old (50 males and 61 females) performed 4 types of stepping motions for 20 s. Stepping motions included bilateral stepping (back/forth and right/left) and unilateral stepping (back/forth and right/left). The number of steps, the average connecting time of a foot during one step, and the average time of both feet touching the floor at the same time (bilateral connecting time) were measured with a foot switch sheet. The trial-to-trial reliability was very high (above 0.86) except for the bilateral connecting time in the bilateral stepping back/forth test for 70-85 year olds (males: 0.67, females: 0.68). With age, the number of steps was significantly smaller, and the average connecting time and the bilateral connecting time were shorter in all stepping tests. There were significant sex differences in bilateral connecting time for bilateral stepping right and left and the number of steps for the bilateral stepping back and forth and the unilateral stepping right and left tests. The number of steps and average connecting time showed high correlations between bilateral stepping right/left and back/forth (r=0.71-0.94) and between unilateral stepping back/forth and right/left (r=0.87-0.99). There were significant correlations of the average connecting time between bilateral and unilateral stepping motions (r=0.51-0.83), but both stepping motions are considered to have different motion properties from the viewpoint of center of gravity sway. The correlations between the bilateral connecting time and the number of steps in bilateral stepping were relatively low (males: /r/<0.70, females: /r/<0.57). The bilateral connecting time was near 0 s in many males; thus, it may depend greatly on individual or sex differences in stepping strategy. These results suggest that the stepping motions used in this study can evaluate dynamic balance ability, and that the unilateral test may be useful for the elderly who cannot walk independently with ease.