Personalized accelerometer cutoffs to evaluate moderate to vigorous physical activity in persons with multiple sclerosis: a feasibility study

BACKGROUND: Physical activity is fundamental for multiple sclerosis (MS) care, and this is particularly true when persons do moderate to intensity vigorous physical activity (MVPA), as recommended by the World Health Organization. This study aimed to evaluate whether a protocol to determine individualized MVPA cutoff from accelerometer is feasible in terms of difficulty perception, physical exertion and evaluation time in persons with MS. METHODS: Two accelerometers, were calibrated against an oxygen consumption system, during the simulation of 4 different daily tasks. The feasibility was assessed in terms of participants' overall difficulty, physical exertion and task durations. RESULTS: For persons with MS (N.=28), median overall difficulty evaluated with a visual analog scale (0-10) ranged from 3 for the ironing to 6.5 for the stair task. The median physical exertion assessed with the Borg Test ranged from 9 (very light) for the ironing, to 13 (somewhat hard) for the stairs task. The mean overall time to realize the evaluation was 41 minutes. MVPA cutoffs were different between participants, tasks and accelerometer position. CONCLUSIONS: Every participant included in this study realized the entire protocol without particular difficulty. The entire protocol was realized in less than 41 minutes, with an overall and physical exertion results not higher than those observed in walking tests currently practiced in persons with MS. MVPA cutoffs varied in function of individuals, daily life activities and accelerometer positions; these variations are in favor of a previous individualized calibration to enhance accuracy of MVPA daily life measurements in persons with MS.