## 2 Materials and Methods
### Data Analysis  
CoP in both the mediolateral (ML), side-to-side, and anterior-posterior (AP), front-to-back planes were used to quantify balance. The CoP time series is the point of location of the resultant ground reaction vertical force; it is a commonly used quantitative measurement to characterize one's balance. From the CoP time series, displacement, velocity, and frequency characteristics were computed [5] using MATLAB (MathWorks, Inc., Natick, MA, USA, R2021b). Root-mean-squared (RMS) displacement and peak-to-peak range of displacement (maximum distance, or MAXD) were computed for ML and AP CoP. Further, combined parameters (total excursion (TOTEX), mean velocity (MVELO), and mean frequency (MFREQ)) were computed using the AP and ML CoP. The above parameters were computed using Equations (1)-(7), respectively [5,18]:  
Maximum distance (MAXD):  
\[\text{MAXD}=\text{max}(\text{x}(\text{i}))-\text{min}(\text{x}(\text{i})) \tag{1}\]  
where x(i) is the COP data for the sample number \"i\".  
Root-mean-square of trunk position (RMS):  
Figure 4: (**A**) Limits of Stability (LoS): Data collection with xEMU Vest for forward, backward, right, and left. (**B**) Wide stance (left) and tandem stance (right).  
\[\text{RMS}=\sqrt{\frac{1}{\text{N}}{\sum_{i=1}^{\text{N}}}{\left[\text{x(i)}\right] }^{2}} \tag{2}\]  
where x(i) is COP data for the sample number \"i\", N = number of samples.  
Total Excursion (TOTEX)  
\[\text{TOTEX}=\sum_{n=1}^{\text{N}-1}\sqrt{\left(\text{AP}[\text{n}+1]-\text{ AP}\Big{[}\text{n}\Big{]}^{2}\right)+\left(\text{ML}[\text{n}+1]-\text{ML}\Big{[} \text{n}\Big{]}^{2}\ \right)} \tag{3}\]  
Calculated as the respective distance between AP and ML directions of the CoP from the origin where N is the number of samples and n is the sample number.  
Mean Distance (MDIST)  
\[\text{RD}\left[\text{n}\right]=\sqrt{\text{AP}_{n}^{2}+\text{ML}_{n}^{2}}, \text{n}\ =\ 1,\ \ldots,\ \text{N} \tag{4}\]  
MDIST is calculated as the distance between the CoP AP and ML direction from the origin where N is the number of samples, RD is the resultant distance from the origin, and n is the sample number.  
Mean Velocity (MVELO)  
\[\text{MVELO}=\frac{\text{TOTEX}}{\text{T}} \tag{5}\]  
Calculated as TOTEX over total time (T).  
Root-mean-square distance (RDIST)  
\[\text{RDIST}=\sqrt{\frac{1}{\text{N}}{\sum_{n=1}^{\text{N}}}\text{RD}[\text{n} ]^{2}} \tag{6}\]  
Calculated as the square root of the sum of the squared MDIST.  
Mean Frequency (MFREQ)  
\[\text{MFREQ}=\frac{\text{MVELO}}{2\pi\text{MDIST}} \tag{7}\]  
Calculated as the ratio of the MVELO to the MDIST.  
In terms of statistical analysis, the software RStudio version 4.2.1 was used. The LoS datasets were non-normally distributed. The LoS was analyzed using Wilcoxon (rank-sum) and the Kruskal-Wallis' (one-way ANOVA) significance tests. The Holm-Bonferroni method was used to determine the adjusted \(p\)-values. All reported \(p\)-values are the adjusted \(p\)-values. Three groups were analyzed: unsuited, xEMU Vest, and HUT. The LoS data were not normally distributed. Therefore, the Wilcoxon rank-sum significance test was used to compare specific groups: (1) unsuited vs. xEMU Vest, (2) unsuited vs. HUT, and (3) xEMU Vest vs. HUT), while the Kruskal-Wallis was used for the overall group comparison. The standing balance data were analyzed using [PERSON] and Kruskal-Wallis' significant tests. The Holm-Bonferroni method was used to cross-check all significant findings to eliminate \"chance significance\".