Strength training of the upper extremity in virtual reality with an exoskeleton robot

Abstract

Muscle weakness has been identified as the major functional impairment that stroke patients encounter. We developed two games for strength training of the arm that can be played with an exoskeleton robot: 1) A sustained arm flexor muscles' action protocol, where the training is adapted online within the movement considering the individual torque profile and 2) an isometric explosive-type rate of torque development training task. One male subject, two years post-stroke with moderate disability of the right arm tested both games for training of elbow flexion and extension in a single session with respect to feasibility. Measured were torques, work per repetition, total work, power, maximum voluntary contraction, rate of force development, ratio between pliometric to miometric torque, time under tension, fatigue and smoothness. The subject was able to perform the two games. The data recorded during task execution allowed to measure all the desired muscular performance capacities. We implemented two unique and complementary robot-assisted strength training protocols that allow perform virtual game-like tasks with the arm therapy robot ARMin by a subject post-stroke. Furthermore, we could assess muscular performance.