Exercise intensity is increased during upper limb movement training using a virtual rehabilitation system

Upper-limb (UL) training interventions are increasingly being developed using virtual reality (VR) platforms. However, since motor recovery is related to exercise intensity and task difficulty, it is important to determine whether these factors are considered in VR applications applied in different centers for patients with different motor impairment levels. We define exercise intensity as the total number of movement repetitions divided by the total minutes in active therapy. The main objective of this study was to determine the training intensity of a clinically-applied treatment program using VR in 3 centers involved in a multi-site study. Our secondary objective was to determine if training intensity differed among patients with different levels of UL sensorimotor impairment. Patients with sub-acute unilateral stroke in the middle cerebral artery area (<; 6 mo post-stroke) with Fugl-Meyer Assessment (FMA-UL) scores ranging from 14-57, completed 10 50-minute UL training sessions with a VR rehabilitation application over 2 weeks, in rehabilitation centers located in 3 countries. Total training time (minutes), total number of movement repetitions, and success rates were extracted from game activity logs. Intensity was calculated for each game for each participant, related to UL impairment and compared between centers. Exercise intensity was higher in one of the 3 centers (p<; 0.01). Participants had most difficulty with the games involving bilateral coordination and lateral reaching. Participants with higher FMA-UL scores had longer total training times (r = 0.40, p = 0.03) and started the training earlier within the subacute phase (r = -0.38, p = 0.04). Participants who used the VR system later in the subacute phase trained at a higher intensity than those who started earlier (r = 0.43, p = 0.02). However, their level of training intensity was not related to UL impairment. The level of intensity attained with this training program was much higher than that reported in current stroke therapy practice. Despite different training centers, therapists progressed patients through the training program using similar training principles. Therefore, VR rehabilitation systems can be used to deliver intensive exercise programs in a standardized way and can be tailored to individual impairment levels.