# Lifting Activities Assessment Using Lumbosacral Compression and Shear Forces
## 4 Discussion
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & **LI** & \multicolumn{2}{c}{**Maximum**} & \multicolumn{2}{c}{**Mean**} & \multicolumn{2}{c}{**Range**} \\ \cline{2-9}  & & & \(p\) **Value** & **[PERSON]’s d** & \(p\) **Value** & **[PERSON]’s d** & \(p\) **Value** & **[PERSON]’s d** \\ \hline \multirow{9}{*}{Upper Model} & \multirow{3}{*}{\(CF_{L5-S1}\) [N]} & 1 vs. 2 & 0.107 & 0.17 & **0.018** & 0.29 & **\textless{0.001}** & 1.37 \\  & & 1 vs. 3 & **0.003** & 1.08 & **\textless{0.001}** & 2.71 & **\textless{0.001}** & 3.28 \\  & & 2 vs. 3 & **0.001** & 1.22 & **\textless{0.001}** & 2.19 & **\textless{0.001}** & 1.95 \\  & & 1 vs. 2 & 0.054 & 0.42 & **0.016** & 0.59 & **\textless{0.001}** & 1.72 \\  & & 1 vs. 3 & **\textless{0.001}** & 3.05 & **\textless{0.001}** & 5.28 & **\textless{0.001}** & 2.46 \\  & & 2 vs. 3 & **\textless{0.001}** & 3.40 & **\textless{0.001}** & 4.83 & 0.098 & 0.64 \\  & & 1 vs. 2 & 0.062 & 0.52 & 0.850 & 0.23 & **0.003** & 0.86 \\  & \(|CF_{L5-S1}-\) & 1 vs. 3 & **\textless{0.001}** & 3.65 & 0.105 & 0.64 & **\textless{0.001}** & 3.09 \\  & & 2 vs. 3 & **\textless{0.001}** & 3.13 & 0.078 & 0.81 & **\textless{0.001}** & 2.62 \\ \hline \multirow{9}{*}{Lower Model} & \multirow{3}{*}{\(SF_{L5-S1}\) [N]} & 1 vs. 2 & **0.001** & 0.94 & **0.013** & 0.64 & **0.001** & 0.85 \\  & & 1 vs. 3 & **\textless{0.001}** & 4.82 & **\textless{0.001}** & 5.22 & **\textless{0.001}** & 2.51 \\  & & 2 vs. 3 & **\textless{0.001}** & 4.06 & **\textless{0.001}** & 4.39 & **\textless{0.001}** & 1.98 \\  & & 1 vs. 2 & **0.001** & 1.18 & **0.014** & 0.68 & **0.002** & 1.08 \\  & & 1 vs. 3 & **\textless{0.001}** & 5.06 & **\textless{0.001}** & 4.59 & **0.002** & 2.25 \\  & & 2 vs. 3 & **\textless{0.001}** & 2.25 & **\textless{0.001}** & 2.29 & **0.001** & 1.21 \\  & & 1 vs. 2 & **0.001** & 0.75 & **0.006** & 0.54 & **0.001** & 0.77 \\  & \(|SF_{L5-S1}-\) & 1 vs. 3 & **\textless{0.001}** & 4.44 & **\textless{0.001}** & 4.52 & **\textless{0.001}** & 2.45 \\  & & 2 vs. 3 & **\textless{0.001}** & 3.72 & **\textless{0.001}** & 3.59 & **\textless{0.001}** & 1.93 \\ \hline \multirow{9}{*}{Upper Model} & \multirow{3}{*}{\(SF_{L5-S1}\) [N]} & 1 vs. 2 & **0.002** & 0.93 & **0.011** & 0.55 & **0.034** & 0.91 \\  & & 1 vs. 3 & **\textless{0.001}** & 3.92 & **\textless{0.001}** & 5.40 & **0.002** & 1.52 \\  & & 2 vs. 3 & **\textless{0.001}** & 2.23 & **\textless{0.001}** & 4.52 & **0.006** & 0.73 \\  & & 1 vs. 2 & **0.001** & 1.15 & **0.014** & 0.66 & **0.019** & 1.04 \\  & & 1 vs. 3 & **\textless{0.001}** & 2.67 & **\textless{0.001}** & 4.06 & **0.022** & 1.14 \\  & & 2 vs. 3 & **\textless{0.001}** & 1.23 & **\textless{0.001}** & 2.52 & 0.388 & 0.35 \\  & & 1 vs. 2 & **0.002** & 0.83 & **0.007** & 0.48 & **0.032** & 0.90 \\  & \(|SF_{L5-S1}-\) & 1 vs. 3 & **\textless{0.001}** & 3.59 & **\textless{0.001}** & 5.19 & **0.002** & 1.53 \\  & \(SF_{L5-S1}\)[N] & 2 vs. 3 & **\textless{0.001}** & 2.24 & **\textless{0.001}** & 3.72 & **0.006** & 0.77 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._and mean values decrease with LI while the range values increase with LI (Figure 3a,b, Table 1). These results are similar for both the used model and the lower and upper models (Figure 3a,b, Table 1). Furthermore, considering the values of forces normalized with respect to the \(F_{L5-S1}\) during the standing phase (\(|CF_{15-S10}-CF_{15-S1_{Standing}}|\) in N, Figure 3c), the maximum and range increase with LI (Figure 3c). This result could be affected by the task geometry, resulting in a different initial \(CF_{L5-S1}\) depending on the posture taken by subjects before lifting the load. In fact, in the tasks with LI = 1 and 2, the subject started in a posture closer to standing because the load was placed at an initial vertical height that was close to the subject's pelvis (V = 75 cm in both LIs, see Figure 1) and therefore the subjects did not have to either lean forward excessively with the trunk or bend the legs.