Safety, feasibility, and user perceptions of a biofeedback-integrated postural support system for upper-limb exercise in individuals with spinal cord injury

BACKGROUND: Trunk instability in individuals with spinal cord injury (SCI) compromises safety and efficiency during upper-limb strength training. Integrating passive postural support with real-time biofeedback may help enhance postural stability and support safer exercise participation. OBJECTIVE: This pilot study evaluated the safety, feasibility, and user perceptions of a biofeedback-integrated postural support system for upper-limb exercise in individuals with SCI, with additional comparison of perceptions between complete and incomplete injury groups. METHODS: Sixteen participants with SCI (9 complete, 7 incomplete) performed upper-limb exercise using a biofeedback-integrated postural support system incorporating pressure and inertial measurement unit sensors, and then completed a safety evaluation questionnaire. Quantitative data were analyzed descriptively and compared between complete and incomplete SCI groups. Semi-structured interviews were conducted to explore perceived benefits, usability barriers, potential hazards, and design improvements. RESULTS: Overall safety-related ratings were positive, with all items scoring 4.00 or higher on a 5-point Likert scale. The highest-rated item was belt-related safety, indicating minimal body pressure or pinching in the belt area (4.81 ± 0.39), while the lowest-rated item was the perceived strength of the system for maintaining correct posture during exercise (4.00 ± 0.86). No statistically significant differences were observed between complete and incomplete SCI groups. However, participants with complete SCI tended to rate posture-support strength higher than those with incomplete SCI (4.33 ± 0.87 vs. 3.57 ± 0.79, p = 0.102, Hedges' g = 0.86). Qualitative feedback suggested perceived benefits in trunk stability, exercise motivation, and rehabilitation applicability, while also identifying areas for improvement, including independent operation, arm support, wrist-strap stability, and handle comfort. CONCLUSIONS: The system demonstrated favorable user-perceived safety and preliminary feasibility for upper-limb exercise in individuals with SCI. Participants perceived the system as helpful for trunk stability and exercise motivation; however, future iterations should improve independent operation, adaptive support, ergonomic design, and multimodal feedback to address diverse functional needs.