A New Method of Recording F-waves from the Vastus Lateralis Muscle

Abstract

F-waves are compound muscle action potentials generated by the retrograde activation of alpha motoneuron axons and the backfiring of anterior horn cells upon electrical stimulation. Traditionally, F-waves are recorded from the vastus lateralis muscle by electrical stimulation of the groin, but this method has several limitations. We placed stimulating electrodes at 50–80% of the proximal thigh to investigate better stimulation sites. As a result, most subjects had successful F-wave recordings with electrical stimulation at 70% and 80% of the thigh. However, some participants experienced severe pain from the electrical current. To address this issue, we tested varying the frequency of electrical stimulation while recording F-waves from the vastus lateralis muscle and found that 0.2-Hz stimulation reduced pain more than the conventional 0.5-Hz stimulation. These findings have potential clinical applications in the future, as they may help improve patient comfort and cooperation during F-wave recording procedures.