Footwear Effects on Postural Stability Are Greater During Unilateral than Bilateral Squat-Based Strength Training Exercises

Footwear may influence postural stability during resistance training, but its effects during bilateral and unilateral squat-based exercises remain poorly understood. This study analyzed the effects of conventional sports footwear on center of pressure (CoP) behavior and vertical ground reaction forces during the barbell back squat and barbell split squat. Eight resistance-trained men completed two sessions. After load determination and familiarization, participants performed both exercises under shod and unshod conditions using a wireless dual force plate system. CoP displacement, CoP velocity, vertical ground reaction forces, and inter-limb vertical force asymmetry were analyzed using a two-way repeated-measures ANOVA. Footwear and exercise type showed moderate or large effects on all analyzed variables, while the footwear × exercise interaction showed moderate or large effects on 12 of 16 variables. CoP displacement and velocity were generally higher under shod than unshod conditions, with moderate to large footwear effects (η2p = 0.068–0.772). Mediolateral CoP changes were small in the back squat (0.0–6.2%) but clearly larger in the split squat (18.6–28.8%). During the split squat, the dominant/front limb produced greater force unshod than shod, whereas the non-dominant/rear limb showed the opposite pattern. These preliminary findings from this pilot study indicate that conventional sports footwear can alter postural stability and inter-limb vertical force distribution, especially during unilateral squat-based exercises.