Reducing Barbell Tilt Angle Improves Bilateral Symmetry in Ground Reaction Forces during Barbell Back Squats

초록

Symmetry in lower-limb muscle strength is important for the improvement of sports performance and the minimization of musculoskeletal injuries. Because upper-body motions were reported to relate with lower-limb muscle force distributions, we aimed to examine whether changes in barbell tilt angle improve symmetries in vertical ground reaction force (vGRF). In this study, we developed a simple monitoring system with an accelerometer to assist a participant in maintaining the barbell as horizontal as possible. The system produced alarm sounds from the side of the barbell tilting downward. Twenty-four healthy participants performed barbell-back squats. The magnitudes of the barbell tilt angle and asymmetry for vGRF before and after the alarm notifications were compared. The barbell tilt angles were significantly reduced after providing alarm sounds for both the descending (paired t-test, p < 0.012) and ascending (p < 0.035) phases of the squats. Reductions in asymmetry for vGRF were significant with alarm notifications for both the descending (p < 0.014) and ascending (p < 0.027) phases. Asymmetries in the vGRF were found to decrease as the barbell angle decreased with the accelerometer alarm system. The barbell alarm system could be useful as a potential assistance device for practical exercise situations. © The Author(s), under exclusive licence to Korean Society for Precision Engineering 2025.

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