Assessing the "rule of 10" in Orthopedic Robot-Aided Rehabilitation for Tailoring Exercise Dose

Robot-aided rehabilitation has gained attention for its ability to deliver standardized, repeatable therapeutic interventions. A key but underexplored aspect of these protocols is determining the optimal therapy dose, often defined by the number of repetitions. This study examines the "Rule of 10,"a guideline used by physiotherapists to adjust exercise intensity based on patient-reported pain and exertion, recommending that the Cumulative Perceived Strain (CPS) should not exceed 10 to avoid overstrain. Eight orthopedic patients participated in a robot-aided rehabilitation session using a KUKA Lightweight Robot 4+ controlled by a tunable interaction controller. The relationship between the number of repetitions performed and clinical scales was examined across different CPS values. The results demonstrated that CPS = 11 returned strong statistically significant correlations (ρ = 0.79 and ρ = -0.75 for CMS and DASH, respectively). This indicates that 11 may be a more suitable threshold for customising therapy intensity. Future research should endeavour to refine therapy protocols by integrating real-time assessments of strain and clinical conditions.