Primary objective: To examine whether vibration to the palm of the hand induces motor activity in the forearm muscles of individuals with post-stroke and healthy young adults. We hypothesized that the vibration would induce antagonistic muscle activities via the motor cortex.
Research design: Observational study using the between- and within-subjects mixed design.
Methods and procedures: Vibratory stimulation was applied to the palm of the paretic and non-paretic hands in seven post-stroke hemiplegia, and of the right hand in 22 healthy young adults in the eyes-closed and eyes-open conditions. Surface electromyography (sEMG) was recorded from the forearm extensors and flexors and the sEMG amplitudes were analyzed.
Main outcomes and results: The extensor activities were significantly larger than that of the flexors in all hands. Especially, the extensor activities were augmented when the eyes were open in the paretic and non-paretic hands. Moreover, there was greater muscle activity in the non-paretic hand compared with the paretic hand.
Conclusions: These novel findings revealed that vibration to the palm augmented the activity of the antagonistic forearm extensors, especially in the paretic hand, which was induced via top-down cortical modulation. Thus, it can be utilized to improve the impaired forearm extensors in post-stroke rehabilitation.
Keywords: Vibratory stimulation; antagonist vibratory response; post-stroke rehabilitation; surface electromyography.