## 3 Results
### Measures of Dynamic Stability: Time Series Qualitative Analysis  
Visual inspection of dynamic balance metrics reveals a similar shape of the time series data during the stance phase of gait associated with both the first and second steps for the Parkinson's and control groups (Figure 6). Note that the data in Figure 6 represent changes in the mean position of dynamic balance metrics during two consecutive steps \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Parameters** & **CON** & **PD** & **(CON\(-\)PD)** & **\(p\)-Value** & **Diff CI** \\ \hline First Stance Time (s) & 0.873 (0.024) & 0.945 (0.024) & \(-\)0.0719 (0.034) & 0.051 & (\(-\)0.144, 0.000) \\ \hline First Swing Time (s) & 0.581 (0.017) & 0.621 (0.018) & \(-\)0.0401 (0.025) & 0.126 & (\(-\)0.093, 0.013) \\ \hline First Step Length (m) & 0.755 (0.018) & 0.747 (0.018) & 0.0072 (0.027) & 0.783 & (\(-\)0.047, 0.062) \\ \hline Second Stance Time (s) & 0.874 (0.024) & 0.894 (0.024) & \(-\)0.0206 (0.034) & 0.554 & (\(-\)0.093, 0.052) \\ \hline Second Swing Time (s) & 0.562 (0.017) & 0.556 (0.018) & 0.006 (0.025) & 0.795 & (\(-\)0.046, 0.059) \\ \hline
**Second Step Length (m)** & **0.693 (0.018)** & **0.609 (0.018)** & **0.083 (0.026)** & **0.005** & **(0.029, 0.138)** \\ \hline Stride Length (m) & 1.447 (0.035) & 1.358 (0.036) & 0.0896 (0.050) & 0.092 & (\(-\)0.016, 0.195) \\ \hline Stride Width (m) & 0.124 (0.010) & 0.141 (0.010) & \(-\)0.018 (0.015) & 0.241 & (\(-\)0.048, 0.013) \\ \hline Velocity (m/s) & 1.018 (0.040) & 0.907 (0.040) & 0.111 (0.056) & 0.065 & (\(-\)0.008, 0.229) \\ \hline \hline \end{tabular} Data are presented as mean (standard error). CON = control; PD = [PERSON]’s disease; First = leading limb variables; Second = trailing limb variables; Stride width = step width; CON\(-\)PD = difference value; Diff CI = confidence intervals for the CON-PD difference; stride length, stride width, and gait velocity are mean values for the sequence of movements of the leading and trailing limbs. A significance level of \(\alpha\) = 0.05 was set. Note: the operational definitions for each gait parameter are provided in Section 2.4.  
\end{table} 
Table 4: Spatiotemporal gait parameters during obstacle-crossing. Figure 5: Comparison between the control (CON) and Parkinson’s (PD) groups for mean step length for the first and second steps. The 95% confidence intervals for each mean are included to illustrate significant differences, i.e., confidence intervals not overlapping, both within and between steps. Notably, this also suggests differences in the first and second steps within each group (CON and PD). while stepping over the obstacle: (1) the first step is stance-phase data of the right limb with the leading left limb, and (2) the second step is stance-phase data of the left limb with the trailing right limb. What follows is a description of the position and positional changes for dynamic balance metrics relative to specific gait Events (see Section 2.5 for detailed operational definitions):  
* First double support one (FDS1): The COP-COM, COP-XCOM, and UMAX-XCOM all show positive values at zero percent of stance for the first step, indicating that the COM and XCOM are medial to the COP and UMAX. The larger value for UMAX-XCOM is related to the location of the lateral boundary of the base of support, i.e., the head of the fifth metatarsal. * Midstance one (MST1): At 50% of stance, the COP-XCOM and UMAX-XCOM demonstrate increasing positive values, which suggests a greater distance from the base of support (BOS), i.e., a less stable position. * First double support two (FDS2) (note: FDS2 is at the same point in time as second double support for the right stance limb): The COP-COM, COP-XCOM, and UMAX-XCOM similarly show positive values but also seem to reach a peak, i.e., reach their greatest values. We expected to see this since this period is a critical transition when the leading limb is initiating contact with the ground and the trailing limb is in its pre-swing period.