Intensity-dependent corticospinal facilitation by repetitive peripheral magnetic stimulation: evidence for a major contribution of group I afferents

Repetitive peripheral magnetic stimulation (PMS) facilitates corticospinal excitability in an intensity-dependent manner and requires suprathreshold intensities. High-intensity PMS acts faster than lower-intensity suprathreshold stimulation, whereas subthreshold stimulation does not significantly modulate corticospinal excitability. This facilitation is abolished by ischemia and linked to short-latency motor unit responses, supporting a major contribution of large-diameter group I afferent input with a substantial Ia component. These findings inform optimization of PMS protocols for neurorehabilitation.