2004 Volume 31 Issue 1 Pages 70-75
Electrical stimulated muscle activity was evaluated using MRI. Two types of electrical stimulation, low and medium frequencies, were used and compared.
Subjects were eleven healthy males. The electrical stimulation was applied to the rectus femoris, vastus medialis, and vastus lateralis muscles. MRI was performed before and immediately after the stimulation. Each muscle was identified, and ROI was determined. T2 value was deduced from each ROI, and increase ratios of T2 value in each ROI were compared between medium and low frequencies.
Increase ratios of T2 value (IRT2) of the surface and the deep layers of rectus femoris, vastus medialis, and vastus lateralis muscles were compared between the two electrical stimulations. IRT2 of the deep layers were decreased in all the muscles, however there were no statistical significances. In addition, no difference was observed between the two stimulations in each muscle.
Threshold of the nerve is much lower than that of the muscle, and the nerve of the motor point is stimulated and activated even by using medium frequency electrical stimulation. Impedance deteriorates with increasing stimulation frequency, and skin discomfort should therefore be decreased by using a medium frequency.
