# Understanding Balance Control in the Context of Riding a Personal Mobility Device
## 4 Discussion  
### Performance and Pattern of the Targeted Weight Shifting  
#### 4.1.1 Effects of Target Distance on the Weight-Shifting Performance  
In the weight-shifting task, the target distance was found to affect the time, fluency, and accuracy of the COP movements, which is consistent with the findings from previous studies [30; 37; 38]. When the target distance was increased, the MT increased, the movement trajectory fluctuated more, and a larger variation with more time was required around the goal target. In other words, a farther target distance increases the task difficulty and affects the movement strategy. In this circumstance, the postural control requires more resources and takes longer to execute with larger amplitudes. This relationship  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**DV**} & \multirow{2}{*}{**Target Distance**} & \multicolumn{6}{c}{**Target Direction**} \\ \cline{3-6}  & & **E** & **N** & **NE** & **NW** & **W** \\ \hline \multirow{4}{*}{MDIST\({}_{\text{ML}}\)} & Distance 1 & 0.09\({}^{\text{ab}}\) (0.01) & 0.08\({}^{\text{Ab}}\) (0.01) & 0.08\({}^{\text{Ab}}\) (0.01) & 0.08\({}^{\text{Ab}}\) (0.01) & 0.12\({}^{\text{a}}\) (0.01) \\  & Distance 2 & 0.11 (0.01) & 0.09\({}^{\text{A}}\) (0.01) & 0.10\({}^{\text{A}}\) (0.01) & 0.09\({}^{\text{AB}}\) (0.01) & 0.12 (0.02) \\  & Distance 3 & 0.13 (0.01) & 0.18\({}^{\text{B}}\) (0.03) & 0.13\({}^{\text{B}}\) (0.01) & 0.13\({}^{\text{B}}\) (0.02) & 0.12 (0.01) \\  & Distance 1 & 0.11\({}^{\text{Aab}}\) (0.01) & 0.09\({}^{\text{Ab}}\) (0.01) & 0.10\({}^{\text{Ab}}\) (0.01) & 0.10\({}^{\text{Ab}}\) (0.01) & 0.14\({}^{\text{a}}\) (0.02) \\ RDIST\({}_{\text{ML}}\) & Distance 2 & 0.13\({}^{\text{AB}}\) (0.02) & 0.11\({}^{\text{A}}\) (0.01) & 0.12\({}^{\text{A}}\) (0.01) & 0.11\({}^{\text{AB}}\) (0.01) & 0.15 (0.02) \\  & Distance 3 & 0.16\({}^{\text{B}}\) (0.02) & 0.22\({}^{\text{B}}\) (0.03) & 0.15\({}^{\text{B}}\) (0.02) & 0.16\({}^{\text{B}}\) (0.02) & 0.15 (0.01) \\  & Distance 1 & 0.85\({}^{\text{A}}\) (0.09) & 0.77\({}^{\text{A}}\) (0.06) & 0.79\({}^{\text{A}}\) (0.07) & 0.82\({}^{\text{A}}\) (0.09) & 0.88 (0.07) \\ MVEL & Distance 2 & 1.11\({}^{\text{B}}\) (0.14) & 1.00\({}^{\text{B}}\) (0.08) & 0.90\({}^{\text{B}}\) (0.07) & 0.91\({}^{\text{AB}}\) (0.07) & 0.96 (0.10) \\  & Distance 3 & 1.10\({}^{\text{B}}\) (0.14) & 1.54\({}^{\text{C}}\) (0.17) & 1.42\({}^{\text{B}}\) (0.26) & 1.0 was also reported in other studies regarding voluntary movements of other limbs under goal-directed movements with speed and accuracy trade-off.  
However, as shown in the post-hoc tests, the DC was not significantly affected by the target distance. This indicated that the farther target distance of the COP movements not only induced more fluctuations toward the off-axis but also increased the movement length toward the on-axis, and their ability to control the COP movement direction was not affected by the distance. This indicates the ability to precisely aim a target was not affected.  
In terms of accuracy, [PERSON] et al. [30] showed that increasing the target distance decreases the accuracy of the targeted COP movement. In this study, the TESSS and DT were significantly increased as the target distance increased but the ME and the TA were not significantly affected. These indicated that the SSM lasted longer with an increase in the target distance but the controls of the movement around the target were not significantly different by the given target distance. From this perspective, the precision of weight-shifting control at the target area was not affected by the target distance in this experiment.