Investigating measures of intensity during a structured upper limb exercise program in stroke rehabilitation: An exploratory study

Objectives: To use 3 measures of intensity—time, observed repetitions, and wrist accelerometer activity counts—to describe the intensity of exercise carried out when completing a structured upper limb exercise program, and to explore whether a relationship exists between wrist accelerometer activity counts and observed repetitions. Design: Observational study design. Setting: Rehabilitation center research laboratory. Participants: Community-dwelling stroke survivors (N=13) with upper limb hemiparesis. Intervention: Not applicable. Main Outcome Measures: Time engaged in exercise, total repetitions, and accelerometer activity counts for the affected upper limb. Results: Mean session time ± SD was 48.5±7.8 minutes. Participants were observed to be engaged in exercises for 63.8%±7.5% of the total session time. The median number of observed repetitions per session was 340 (interquartile range [IQR], 199–407), of which 251 (IQR, 80–309) were purposeful repetitions. Wrist accelerometers showed the stroke survivors' upper limbs to be moving for 75.7%±15.9% of the total session time. Purposeful repetitions and activity counts were found to be significantly correlated (ρ=.627, P < .05). Conclusions: Stroke survivors were not actively engaged in exercises for approximately one third of each exercise session. Overall session time may not be the most accurate measure of intensity. Counting repetitions was feasible when using a structured exercise program and provides a clinically meaningful way of monitoring intensity and progression. Wrist accelerometers provided an objective measure for how much the arm moves, which correlated with purposeful repetitions. Further research using repetitions and accelerometers as measures of intensity is warranted.