Pain reduction method in recording F-waves from the vastus lateralis muscle.

Abstract

Conventional recording of F-waves from the vastus lateralis muscle causes severe pain in some subjects. Thus, we aimed to investigate the effects of the stimulation frequency on pain and F-wave parameters when recording F-waves from this muscle and to develop a method for recording F-waves from the vastus lateralis muscle that causes minimal pain. The subject's femoral nerve was electrically stimulated at 0.5 or 0.2Hz 30 times, while F-waves were recorded from the vastus lateralis muscle. Pain intensity was measured immediately using a visual analog scale. In addition, the visual analog scale, F-wave persistence, F-wave latency, and F/M amplitude ratio were compared between F-wave recordings with 0.5-Hz electrical stimulation and those with 0.2-Hz electrical stimulation. Eleven healthy men participated in this study. The visual analog scale and F-wave persistence decreased when electrical stimulation at 0.2Hz was applied compared with electrical stimulation at 0.5Hz. Electrical stimulation at 0.5Hz increased pain due to temporal summation. However, electrical stimulation at 0.2Hz did not cause temporal summation, suggesting reduced pain and excitability of the alpha motor neuron pool.