## 3 Results
### Bottock Pressure  
To analyze the characteristics of buttock pressure according to the types of wheelchairs, the differences in force, mean pressure (MP), peak pressure on the ischial tuberosity (IPP), and peak pressure on the sacrum (SPP) were compared between the double-sliding and non-sliding wheelchairs in IUP, fully inclined position (FRP), and RUP. Table 3 and Figure 5 show the results of the comparison in the average values of buttock pressure between double-sliding and non-sliding. In IUP, force and MP were higher in non-sliding than in double-sliding, though there was no statistically significant difference. Moreover, IPP was higher than SPP in both conditions. There was no significant difference in IPP between the two conditions; however, the SPP of non-sliding was 5.79 kPa, which was significantly higher than that of double-sliding (_p_ < 0.05). In FRP, force, MP, IPP, and SPP did not show any significant difference between the two conditions, though the average values of IPP and SPP tended to be higher in non-sliding than in double-sliding. In RUP, there was no significant difference between the two conditions for force, MP, and IPP; however, SPP was significantly larger in non-sliding than in double-sliding by 6.13 kPa (_p_ < 0.05). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Condition**} & \multirow{2}{*}{**Variable**} & \multirow{2}{*}{\begin{tabular}{c} **Double-** \\ **Sliding** \\ \end{tabular} } & \multirow{2}{*}{\begin{tabular}{c} **Non-** \\ **Sliding** \\ \end{tabular} } & \multirow{2}{*}{**Mean** **Difference**} & \multirow{2}{*}{**SE**} & \multicolumn{2}{c}{**95\% CI**} & \multirow{2}{*}{_t-Value_} \\ \cline{3-3} \cline{6-10}  & & Force (\%BW) & \(17.01\pm 4.44\) & \(18.45\pm 5.37\) & \(-1.44\) & \(1.48\) & \(-1.91\) & \(4.79\) & \(-0.970\) \\ \cline{2-10}  & Mean pressure (kPa) & \(1.33\pm 0.26\) & \(1.47\pm 0.38\) & \(-0.14\) & \(0.14\) & \(-0.18\) & \(0.45\) & \(-0.978\) \\ \cline{2-10}  & Peak pressure (kPa) & \begin{tabular}{c} Ischial \\ tuberosity \\ \end{tabular} & \(25.22\pm 15.73\) & \(20.37\pm 11.33\) & \(4.85\) & \(2.61\) & \(-10.74\) & \(1.05\) & \(1.861\) \\ \cline{2-10}  & Sacrum & \(7.61\pm 2.85\) & \(13.39\pm 7.68\) & \(-5.79\) & \(2.01\) & \(1.23\) & \(10.34\) & \(-2.875\) * \\ \hline \multirow{2}{*}{FRP} & Force (N/kg) & \(14.94\pm 4.32\) & \(13.83\pm 1.50\) & \(1.11\) & \(1.17\) & \(-3.75\) & \(1.52\) & \(0.955\) \\ \cline{2-10}  & Mean pressure (kPa) & \(1.12\pm 0.27\) & \(1.23\pm 0.46\) & \(-0.11\) & \(0.12\) & \(-0.16\) & \(0.37\) & \(-0.930\) \\ \cline{2-10}  & Peak pressure (kPa) & \
\begin{tabular}{c} Ischial \\ tuberosity \\ \end{tabular} & \(14.20\pm 7.05\) & \(18.09\pm 8.32\) & \(-3.89\) & \(2.36\) & \(-1.45\) & \(9.23\) & \(-1.648\) \\ \cline{2-10}  & Sacrum & \(14.30\pm 7.03\) & \(18.05\pm 8.31\) & \(-3.75\) & \(2.37\) & \(-1.60\) & \(9.11\) & \(-1.587\) \\ \hline \multirow{2}{*}{RUP} & Force (N/kg) & \(19.90\pm 5.76\) & \(17.23\pm 4.30\) & \(2.67\) & \(1.29\) & \(-5.58\) & \(0.23\) & \(2.081\) \\ \cline{2-10}  & Mean pressure (kPa) & \(1.35\pm 0.25\) & \(1.57\pm 0.34\) & \(-0.22\) & \(0.12\) & \(-0.06\) & \(0.50\) & \(-1.780\) \\ \cline{2-10}  & Peak pressure (kPa) &
\begin{tabular}{c} Ischial \\ tuberosity \\ \end{tabular} & \(26.07\pm 13.45\) & \(23.59\pm 15.39\) & \(2.48\) & \(1.44\) & \(-5.73\) & \(0.78\) & \(1.720\) \\ \cline{2-10}  & Sacrum & \(5.87\pm 2.46\) & \(12.00\pm 7.54\) & \(-6.13\) & \(2.57\) & \(0.31\) & \(11.95\) & \(-2.384\) * \\ \hline \multicolumn{10}{l}{IUP, initial upright position; FRP, fully inclined position; RUP, return upright position; SE, standard error; CI, confidence interval; BW, body weight; *_p_ < 0.05.} \\ \end{tabular}
\end{table} 
Table 3: Comparison of mean buttock pressure between the two conditions (double-sliding versus non-sliding). In addition, the difference in the force, MP, IPP and SPP between the double-sliding and non-sliding wheelchairs was analyzed when the wheelchairs were inclined and repositioned in the range of 100-130\({}^{\circ}\).