Effects of magnetic stimulation compared to electrical stimulation on muscle contraction in quadriceps femoris muscle of healthy subjects: A pilot study

Background/Aims: This study investigated whether pulsed magnetic stimulation contracts superficial and/or deep muscles compared with those induced by electrical stimulations, i.e., low- and kilohertzfrequency currents. Methods: Eight healthy subjects were recruited and measured the quadriceps femoris muscle thickness using ultrasound imaging, and Visual Analog Scale (VAS) for stimulation-induced pain during the same stimulation intensity. Results: Pulsed magnetic stimulation increased the thickness of rectus femoris muscle similar to other electrical stimulations, but not the vastus intermedius muscle. Meanwhile, the pain score of VAS caused by pulsed magnetic stimulation was lower than that by those electrical stimulations. Conclusions: These results suggest that pulsed magnetic stimulation is effective for the contraction of superficial layer muscles without stimulation-induced pain but not for contraction of deep layer muscles. Keywords: pulsed magnetic stimulation; electrical stimulation; stimulation-induced pain; muscle contraction.