Excitability of Spinal Neurons during Relaxation Imagery for 2 Minutes

We investigated spinal neuron function during relaxation imagery by analyzing F-waves generated from the left thenar muscles in response to stimulation of the left median nerve at the wrist in 10 healthy subjects. F-waves were recorded in a resting position and during, immediately after, and at 5, 10, and 15 min after a 2-min relaxation imagery period. Persistence, F/M amplitude ratio, and latency were analyzed from the recorded F-waves. The F/M amplitude ratio was lower in the relaxation imagery condition than in the resting condition, whereas it either recovered or continued to decrease after relaxation imagery. There were no significant differences in persistence and latency before, during, and after relaxation imagery. These results suggested that 2-min relaxation imagery can decrease spinal neural function in healthy subjects and may be useful as a new type of physical therapy for patients suffering from impaired motor control.