# Empirical Validation of a Streamlined Three-Repetition Sit-to-Stand Protocol Using MAI Motion
## 3 Results
Further statistical analysis of the mean CVs for each parameter (generated by calculating the mean CV for each parameter, itself derived by combining the mean CV for that parameter per participant) also showed a modest, but significantly lower, mean CV for 3x vs. 5x (14.3 \(\pm\) 6.0 vs. 15.2 \(\pm\) 6.4, mean \(\pm\) SD, **** \(p\) < 0.0001, Figure 3B). This is presented more qualitatively in Figure 4, which shows a comparison of the mean CV derived from 5x or 3x repeats for every parameter, allowing for the visual identification of the variation between parameters and across categories, as exemplified by the differences in parameters across ankle angle, and knee and hip abduction (Figure 4--denoted by the increase in red intensity). Finally, the correlation analysis revealed a significant correlation between participant age and variability, as defined by the mean CV for each participant (Figure 5). Pearson correlation coefficients were similar for 5x (r = 0.5707) and 3x (r = 0.6213) indicating, once again, that the results obtained for the 3x comparison are comparable to those obtained for the 5x. Figure 1: Overview of kinematic measurements from a participant performing a repeated sit-to-stand (STS) test following analysis of five or three repeats. Measures for each parameter (impulse +ve, impulse \(-\)ve, impulse ratio, and range of motion (Range)) within each of the categories, (**A**) knee angle, (**B**) knee abduction, (**C**) hip angle, (**D**) hip abduction, (**E**) ankle angle, (**F**) L/R movement, and (**G**) core movement, were extracted from video of a participant performing the STS test five times, captured using MAI Motion. Each panel (**A**–**G**) depicts parameters measured across all five repeats (5x—green) or the first three repeats (3x—red), the mean \(\pm\) SD (black lines). Left (L) and Right (R) are shown for all measures except the core. For panels (**A**–**E**), the units are as follows: impulse +ve and impulse \(-\)ve (\({}^{\circ}\)/s); range (\({}^{\circ}\)). For panels (**F**,**G**), units are as follows: impulse +ve and impulse \(-\)ve (m/s); range (m). (**H**) shows the Coefficients of Variance (CV (%)) for each parameter derived from 5x or 3x repeats for each category. No significant differences were observed between the means (using ordinary one-way ANOVA followed by multiple comparisons) or CVs (using paired \(t\)-tests) of any parameter when comparing 5x vs. 3x. Figure 2: Difference in means (DiMs) derived from analysis of 5x or 3x repeats of the STS test grouped by parameter. DiMs for each parameter were derived by establishing the difference between the means calculated from 5x or 3x repeats for each participant (\(n\) = 20) and are presented as % of 5x mean. Mean \(\pm\) SD (black lines) of the DiM for each parameter are shown. Figure 3: Coefficient of variance (CV) derived from analysis of 5x or 3x repeats of the STS test grouped by participant. (**A**) CVs for each parameter (describing knee angle (red), knee abduction (purple), hip angle (blue), hip abduction (orange), ankle angle (green), L/R movement (grey), and core movement (tan)) were derived by comparing the CVs from 5x vs. 3x repeats for each participant (1–20). Mean \(\pm\) SD (black lines) are shown. Statistical significance between 5x vs. 3x for each participant was determined using repeated measures one-way ANOVA, followed by Sidak’s multiple comparisons tests (\({}^{\ast}\)_p_ < 0.025; \({}^{\ast\ast}\)_p_ < 0.002). (**B**) Mean CVs for each parameter across all 20 participants were calculated using data from 5x or 3x repeats. Mean \(\pm\) SD (black lines) are shown. Statistical significance between 5x vs. 3x was determined using a paired \(t\)-test (****\(p\) < 0.0001). Figure 4: Summary of CVs derived from analysis of 5x or 3x repeats of the STS test grouped by parameter. Mean CVs for each parameter from all 20 participants are represented using a colour scale ranging from yellow (ideal/low CV), to amber (acceptable/intermediate CV), to red (poor/high CV)—CV values are depicted in the scale bar at the bottom.