## 5 Conclusions  
This study conducted an in-depth assessment of BSIEs to assess the variations in the measures of the muscle demands in the erector spinae (LES/RES) and bicep femoris (LBF/RBF), the trunk movement, and the stability across the bending, retraction, and transition phases within each cycle of 30 repetitive trunk flexion-extension cycles. In addition, our study emulated realistic conditions by considering intermittent task cycles to fatigue the study participants, as well as asymmetric postures. The overall findings indicated minor benefits in the back region (0-1.8%) but rather substantial advantages in the leg region (10-18%) during repetitive bending. The distribution of the muscle demands across the dynamic spatial movement revealed that although most benefits of the BSIE in the back region occurred during the bending phase, the demands were much higher during the retraction portions. The asymmetric postures led to decreased activation in the LES but increased activity in the RES, LBF, and RBF, aligning with our expectations. After examining the fatigue effects, we found increased back activity (8-12%) during bending and retraction. The BSIE particularly reduced the movement velocities, especially in the lower-back region (-up to 60%). A consistent reduction in the COP velocity (mean \(\sim\)40%) with the BSIE was also seen across all the task portions, as well as with asymmetry and over time, highlighting the positive impact of using BSIEs on the whole-body stability. Future research could explore the differences across exoskeleton designs and examine effects across diverse genders and demographics, providing a more generalizable understanding of the wearable assistive devices' implications during repetitive trunk flexion-extension activities.  
**Author Contributions:** Conceptualization, P.M.K. and E.R.; methodology, P.M.K. and E.R.; software, P.M.K.; validation, P.M.K.; formal analysis, P.M.K.; investigation, P.M.K.; resources, E.R.; data curation, P.M.K.; writing--original draft preparation, P.M.K.; writing--review and editing, P.M.K.; visualization, P.M.K.; supervision, E.R.; project administration, P.M.K. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This study did not receive any external funding.  
**Institutional Review Board Statement:** This study was conducted in accordance with the Declaration of Helsinki and was approved by the Institutional Review Board of Rochester Institute of Technology (HSRO #01113021, approved on 1 April 2022).  
**Informed Consent Statement:** Informed consent was obtained from all subjects involved in this study.  
**Data Availability Statement:** The raw data supporting the conclusions of this article will be made available by the corresponding author upon reasonable request.  
**Conflicts of Interest:** The authors have no conflicts of interests to declare.  
**Appendix A**  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Measure** & **Effect** & \(p\)**-Value** & **Measure** & **Effect** & \(p\)**-Value** \\ \hline \hline \multirow{8}{*}{Mean\_normVelUB1} & A & **0.000** & & A & **0.000** \\  & A*P & 0.465 & & A*P & **0.000** \\  & A*T & 0.106 & & A*T & **0.000** \\  & P & **0.000** & & P & **0.000** \\  & P*T & **0.000** & & P*T & **0.003** \\  & T & **0.000** & & T & 0.148 \\ \hline \end{tabular}
\end{table}
Table 1: _Cont._