Method: Fifteen rabbits were experimentally spinal cord injured at the T10 or T11 spinal cord level. Three kinds of stimulation frequency (10, 20, 40 Hz) and sham control stimulation were applied to the tibialis anterior muscle of each four group for 1 hour per day, for 2 weeks. Muscle fatigue index and peak torque were measured during electrical stimulation, and proportion of the type I muscle fiber was measured at ATPase (pH 9.4) staining.

Results: Complete paraplegia was obtained in all 12 rabbits. Muscle fatigue index and peak torque were not changed after 2 weeks of electrical stimulation in all four groups. The proportion of the type I muscle fiber was reduced in all four groups after 2 weeks. However, 40 Hz stimulation group showed less decline in proportion of type I muscle fiber than control or 10 Hz group.

Conclusion: High frequency electrical stimulation applied at an early stage of spinal cord injury is more effective in preserving muscle endurance than low frequency stimulation. (J Korean Acad Rehab Med 2003; 27: 410-417)

Muscle functions are limited in patients with osteoarthritis of knees. In patients with osteoarthritis, isokinetic testing of knee musculature reveals decreased peak torque and increased walking time(50-ft). The purpose of this study was to demonstrate deficiency in muscular performance of knee, and the relationship between walking time and isokinetic parameters of muscular strength, endurance and pain of knee in patients with osteoarthritis of knees. The subjects were divided into a control group and the study group. The control group consisted of 40 persons without a knee pain, and the study group consisted of 30 patients with osteoarthritis of knees. The peak torque of patients in the study group was decreased by 16∼21%, compared to that the control group. There was a negative relationship between the walking time and the endurance of knee extensors(r=⁣0.7195). These findings suggest that exercises to increase the strength and endurance of extensors and flexors of knees should be emphasized in the rehabilitation program for the osteoarthritis of knees.