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)

Method: Seventeen paraplegic men were enrolled for the study. Isometirc and isotonic strength and dynamic endurance levels for wheelchair propulsion were measured using BTE work simulator. Neurological and demographical characteristics of patients were collected by personal interviews and direct examinations.

Results: The spinal cord injured level showed a significant correlation with dynamic endurance (r=0.503, p＜0.05) but not with the isometric and isotonic strength. The total duration of wheelchair use showed a significant correlation with the isotonic strength (r=0.497, p＜0.05), but not with the isometric strength and dynamic endurance. The age and outdoor activities or exercise time during one week showed no significant correlation.

Conclusion: Spinal cord injured level positively correlated with dynamic endurance. Both cardiorespiratory effect and trunk balance may influence this correlation. The total duration of wheelchair use wasn't correlate with dynamic endurnace. It seems to be more advisable trunk balance training goes with dynamic endurance training in rehabilitation program. (J Korean Acad Rehab Med 2003; 27: 215-219)

Objective: The purpose of this study is to compare muscle strength, endurance and the change of myosin heavy chain isoform after sprint training(ST) and heavy resistance training(HRT).

Method: Fourteen young athletes were enrolled and were randomly assigned into each training group. Before and after training for 8 weeks, the strength and the endurance were evaluated using isokinetic exercise system(Cybex 6000). The specimens of muscle biopsy were obtained from vastus lateralis muscle and were analysed for muscle fiber type using one dimensional electrophoresis.

Results: Peak torque, total work and mean power were increased significantly in both groups, but endurance ratio increased only in the sprint training group(P＜0.05).

The proportions of myosin heavy chain(MHC) IIa fibers were increased in both groups and those of MHC IIb fibers were decreased in both groups(P＜0.05). MHC I fibers were significantly increased in ST group, but decresed in HRT group(P＞0.05).

Conclusion: This study shows that it is possible to increase muscle strength and to achieve fiber type transformation with the sprint training and the high resistance training.

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.