Postural stability in young healthy subjects - Impact of reduced base of support, visual deprivation, dual tasking

To provide normative postural stability data in young subjects.

Ninety-six healthy participants (58W, 28±6y) stood on a force plate during 60s. We measured effects of support width (feet apart, FA; feet together, FT), vision (eyes open, EO; closed, EC), and cognitive load (single task, ST; dual tasking, DT) on anteroposterior (AP) and medio-lateral (ML) ranges, area and planar velocity of center of pressure (COP) trajectory.

All variables increased with FT (AP range, +15%; ML, +185%; area, +242%; velocity, +50%, p<0.0002 for all, MANOVA). Visual deprivation increased COP ranges with added constraints (FT or DT, p=0.002) and increased velocity in all conditions (FA/ST, +16%; DT, +18%; FT/ST, +29%; DT, +23%, p<0.0002 for all). Dual tasking reduced COP displacements with FT (AP range, EO, -15%; EC, -11%; ML range, EO, -19%; EC, -13%; area, EO, -40%; EC, -28%, p<0.0002 for all) and increased velocity in most conditions (FA/EO, +15%; FA/EC, +16%; FT/EO, +7%, p<0.0002 for all).

In young healthy adults, base of support reduction increases COP displacements. Vision particularly affects postural stability with feet together or dual tasking. Dual tasking increases velocity but decreases COP displacements in challenging postural tasks, potentially by enhanced lower limb stiffness.