The purpose of this study was to investigate the influence of weight distribution (WtD) asymmetry on the biomechanics of a barbell back squat. This study included 2 groups of trained individuals who were separated based on a WtD test (n = 14 in each group). They performed the barbell back squats with 2 resistance levels (60 and 75% of 1 repetition maximum) to measure vertical ground reaction force (GRF), tilting, and rotational angular bar displacements. A symmetry index (SI) score of the vertical GRF and the 2 bar displacements were examined to identify the group difference. Results showed that the unequal WtD group displayed a higher vertical GRF SI score (p < 0.05) and greater degrees of the tilting (p < 0.05) and rotational (p < 0.05) angular bar displacements.
The lack of postural control to distribute body weight evenly should be treated properly to gain levelness before participating in high volume of resistance training, and coaches should be conscious of moving in a symmetrical fashion with minimal bar displacements in tilting and rotational manner.