Effects of Overweight on Static Balance Ability, Muscle Activity, and Postural Control Strategies During External...

This study examined the effects of overweight on static balance, postural control strategies, and muscle activity during unexpected external perturbations. Twenty-eight adults in their twenties  were assigned to either a normal-weight group (body mass index: 21.08 [2.55] kg/m2, n = 14) or an overweight group (body mass index: 27.77 [1.85] kg/m2, n = 14). Static balance was assessed under 4 conditions, and surface electromyography measured the onset time and activity of the erector spinae, biceps femoris, and medial gastrocnemius (MG) during balance recovery following forward perturbations. Participants in the overweight group showed significantly greater center-of-pressure sway velocity and distance than normal-weight participants (P < .05). In the normal-weight group, the MG activated earlier than the other muscles (P < .017). In the overweight group, no difference was observed between the MG and biceps femoris, while the erector spinae activated later (P < .017). Muscle activity in the MG and biceps femoris was higher in the overweight group (P < .05). These findings indicate that overweight is associated with reduced static balance and alters postural control strategies, with greater reliance on combined ankle-hip strategies. Increased muscle activity may contribute to fatigue and fall risk.