# Impact of Differing Instability Devices on Postural
## 3 Results  
All variables' means and standard deviations are presented in Table 1. All data were normally distributed. Statistically significant differences were seen in the sway area between conditions (f(2,42) = 5.28, \(p\) = 0.009, \(\eta^{2}\) = 0.18). The result for the control condition (9.64 \(\pm\) 4.53 cm\({}^{2}\)) was significantly lower than those for both the foam pad (13.05 \(\pm\) 4.25 cm\({}^{2}\), \(p\) = 0.009) and block (12.33 \(\pm\) 3.37 cm\({}^{2}\), \(p\) = 0.046). No differences were seen between the foam pad and block conditions (\(p\) = 0.395). Similarly, statistically significant differences were seen in the CoP path length between conditions (f(2,42) = 5.52, \(p\) = 0.007, \(\eta^{2}\) = 0.21), with the result for the control (67.51 \(\pm\) 9.49 cm) being significantly lower than those for both the foam pad (74.36 cm \(\pm\) 9.76 cm, \(p\) = 0.018) and block (76.38 \(\pm\) 14.84 cm, \(p\) = 0.005). No differences were seen between the foam pad and block conditions (\(p\) = 0.442) for the CoP path length. The maximal medial-lateral CoP displacements were significantly different between conditions (f(2,42) = 6.24, \(p\) = 0.004, \(\eta^{2}\) = 0.23). Lower displacements were seen in the control (1.39 \(\pm\) 0.20 cm), which was statistically different from both the foam pad (1.59 \(\pm\) 0.24 cm, \(p\) = 0.002) and block (1.53 \(\pm\) 0.25 cm, \(p\) = 0.03). Again, no differences were present between the foam pad and block conditions. The average sway velocity displayed statistically significant differences between conditions (f(2,42) = 5.53, \(p\) = 0.007, \(\eta^{2}\) = 0.21). The control condition displayed the lowest average sway velocity (6.75 \(\pm\) 0.95 cm/s), which was statistically different from those of both the foam pad (7.44 \(\pm\) 0.98 cm/s, \(p\) = 0.005) and block (7.64 \(\pm\) 1.48 cm/s, \(p\) = 0.018). The maximal anterior-posterior CoP displacements were not significantly different between conditions (f(2,42) = 1.50, \(p\) = 0.23, \(\eta^{2}\) = 0.07). The peak anterior-posterior sway velocity was not significantly different between conditions (f(2,42) = 1.75, \(p\) = 0.186, \(\eta^{2}\) = 0.08). Lastly, the peak medial-lateral sway velocity was not significantly different between conditions (f(2,42) = 2.16, \(p\) = 0.13, \(\eta^{2}\) = 0.09).  
\begin{table}
\begin{tabular}{l c c c c c} \hline \hline  & **Control** & **Foam Pad** & **Block** & \(p\) & **\(\eta^{2}\)** \\ \hline Peak AP Displacement (cm) & 2.05 \(\pm\) 0.56 & 2.31 \(\pm\) 0.62 & 2.23 \(\pm\) 0.58 & 0.23 & 0.07 \\ Peak ML Displacement (cm) & 1.39 \(\pm\) 0.20 & 1.59 \(\pm\) 0.24 \({}^{*}\) & 1.53 \(\pm\) 0.25 \({}^{*}\) & \textless{}0.01 & 0.23 \\ Peak AP Sway Velocity (cm/s) & 26.66 \(\pm\) 6.03 & 28.94 \(\pm\) 7.45 & 29.88 \(\pm\) 6.91 & 0.19 & 0.08 \\ Peak ML Sway Velocity (cm/s) & 26.35 \(\pm\) 6.85 & 28.58 \(\pm\) 5.81 & 29.62 \(\pm\) 5.88 & 0.13 & 0.09 \\ Average Sway Velocity (cm/s) & 6.75 \(\pm\) 0.95 & 74.4 \(\pm\) 0.98 \({}^{*}\) & 7.64 \(\pm\) 1.48 \({}^{*}\) & \textless{}0.01 & 0.21 \\ Path Length (cm) & 6.51 \(\pm\) 9.49 & 74.36 \(\pm\) 9.76 \({}^{*}\) & 76.38 \(\pm\) 1.48 \({}^{*}\) & \textless{}0.01 & 0.21 \\ Sway Area (cm\({}^{2}\)) & 9.65 \(\pm\) 4.53 & 13.04 \(\pm\) 4.25 \({}^{*}\) & 12.33 \(\pm\) 3.37 \({}^{*}\) & \textless{}0.01 & 0.18 \\ \hline \multicolumn{7}{c}{AP = anterior–posterior; ML = medial–lateral; \({}^{*}\) = significantly different from control condition.} \\ \end{tabular}
\end{table}
Table 1: Sway parameter comparisons (mean \(\pm\) SD).