The role of visual information in maintaining postural stability after the maximum exercise for the upper and lower limb muscles

Abstract

The postural stability on a seesaw generating anterior–posterior instability with the eyes open (EO) and then the eyes closed (EC) in young healthy subjects (n = 28) before and 6 min after the maximum bicycle exercise (Wingate test) performed using lower limbs (“leg exercise”) or upper limbs (“hand exercise”) was investigated. It was found that “hand exercise” caused the same increase in average velocity (V, mm/s) and in the average range of sway of the centre of pressure (Qy, mm) as “leg exercise.” However, the duration of V recovery (EC: 2 min 30 s and 50 s; EO: 60 s and 40 s after “leg exercise” and “hand exercise,” respectively) and Qy (EC: 1 min 10 s and 30 s after “leg exercise” and “hand exercise,” respectively; EO: no changes from baseline) was shorter after “hand exercise.” In the presence of visual information, the increment in V decreased more than 2 times after “leg exercise” (+100.5% and + 40.5%, p < 0.01 for EC and EO, respectively) and after “hand exercise” (+73.0% and +30.3%, p < 0.01 for EC and EO, respectively). Moreover, Qy after both exercises remained at the initial level under EO conditions but significantly increased under EC conditions (+42.8%, p < 0.01 after “leg exercise” and +40.3%, p < 0.01 after “hand exercise”). Thus, the maximum exercise for the muscles of the upper limbs causes the same reduction in postural stability as analogous exercise for the muscles of the lower limbs, but the recovery period after “hand” exercise was shorter. The presence of visual information allows the baseline maintenance of postural stability and significantly reduces the strain of postural regulation while standing on a movable support after the maximum “leg exercise” and “hand exercise.”