Interlimb weight adjustments between the lower and upper limbs relate to inaccurate performance during the lateral...

The lateral body weight-shifting task is commonly used in therapeutic programs for patients with orthopedic complaints or hemiparesis. Although the patients usually support themselves using the upper limbs during the task, it is unclear whether the use of upper limbs affects performance accuracy of lateral body weight shifting. Therefore, the aim of this study was to investigate the effects of support by the upper limbs on performance accuracy, particularly on the central tendency effects (i.e. overshooting for light targets and undershooting for heavy targets). Twenty-three able-bodied, neurologically intact individuals, who were right-handed and right-footed participants performed the lateral body weight-shifting task to shift one-third or two-thirds of their body weight toward the left and right lower limbs using support by the upper limbs. The result of correlation coefficients between interlimb weight adjustment and errors showed that the use of the upper limbs and interlimb weight adjustment related to the enhanced central tendency effects. The use of upper limbs generally contributes toward stabilizing posture, however, this is not the case with performance of the lateral body weight shifting. Moreover, the effects of using the upper limb on performance accuracy differed among leftward and rightward weight shifting. This result might be owing to the dominant side of the hand/foot and hemisphere lateralization.