Background & Purpose: Stroke compromises functional characteristics of muscles. Multiple hand function rehabilitation methods have been explored, but none have adequately studied effects on the targeted muscles vs. non-targeted muscles. Selected muscles of stroke survivors affected upper limb were examined during a hand function training program using a novel passive rehabilitation device. 

Methods: Eight-participants (three females) attended 18 one-hour sessions over 6 weeks. Functional training characteristics were randomly altered throughout the training process. Direct visual observation of the ongoing task was blocked to enhance proprioceptive inputs to the cerebellum and cortex. EMG was collected both pre- and post-training from eight muscles, while participants grasped the device to a preset resistance, isometrically, for 30-seconds. Root mean square (RMS) values were estimated, and a paired samples Student t-test (alpha=0.05) was used to estimate differences.

Results:  Biceps brachii and anterior deltoid showed significant reduction in EMG-RMS activity (t23=2.774, p=0.005), while no impact was observed in the triceps brachii and posterior deltoid. Distally, flexor pollicis brevis and flexor digitorum superficialis showed significant reduction in the EMG-RMS activity (t23=1.973, p=0.03), while extensor digitorum and first dorsal interosseous muscles did not.

Conclusions: The results suggest that targeted hand function has a positive impact on the corresponding muscles, improving functionality. They also suggest that targeting hand muscles reduces co-contraction of proximal muscles. This pilot study provided promising results; however, further testing on a larger sample is needed in order to generalize these results.

Evaluation of a novel hand training device and program on muscle pattern activity following stroke