Method: Sciatic nerve of seventy rats was compressed with haemostatic forceps. The experimental group was divided into 4 subgroups according to the intensity and duration of injury: group 1, first degree compression for 5 seconds; group 2, first degree for 30 seconds; group 3, third degree for 5 seconds; and group 4, third degree for 30 seconds. Treadmill exercise was done for either 30 minutes or 2 hours a day, 5 days a week for 4 weeks. Histochemical study of soleus was done before nerve compression and 1 week, 4 weeks after compression.

Results: The fiber diameter of soleus was larger in the experimental group at 4 weeks (p＜0.05). The intensity of injury had greater impact on the recovery of fiber diameter than the duration. Thirty minute exercise was seen to have a earlier recovery of fiber diameter than 2 hours.

Conclusion: These results may provide the basic data to clarify the neurological recovery in relation to the severity of injury, and to help establishing adequate duration of exercise after nerve damage.

Objective: To investigate the effects of treadmill running and swimming exercise for the functional and electrophysiological recovery in rats with sciatic nerve damage, and to evaluate the patterns of recovery according to various degree of intensity and duration of injury.

Method: Sixty male Sprague-Dawley rats (200∼250 g) were used, and divided into the control and the experimental groups. Crushing injuries to the sciatic nerve at the sciatic notch was manipulated using a hemostatic forcep, treadmill and swimming exercise programs were performed for 30 minutes on a daily basis, 5 days a week during the 4 week period. The experimental group was divided into 2 sub-groups in correlation with the intensity of injury, and into 5 and 30 seconds group in correlation with the duration of injury. The test results were analysed by sciatic nerve functional index (SFI) that was obtained through walking tract analysis, and by the amplitude of compound muscle action potentials in calf muscles through the sciatic motor nerve conduction study.

Results: 1) After 4 weeks following sciatic nerve injuries, the SFI were ⁣21.8⁑10.8, ⁣23.1⁑7.0, ⁣32.5⁑9.1 in treadmill, swimming, and control groups, respectively. Treadmill and swimming groups showed markedly improved function compared to the control group. Amplitudes of sciatic nerve compound muscle action potentials in calf muscle were 21.2⁑6.5, 15.9⁑5.8, 12.5⁑2.0 mV in treadmill, swimming, and control groups respectively, and revealed marked electrophysiological improvement in treadmill group. 2) The results concerning the intensity and the duration of injury, nerve recovery patterns showed the most significant improvement in the first degree-5 seconds group in both treadmill and swimming exercise programs.

Conclusion: These findings suggest that the treadmill and swimming exercises have significantly better effect in the regeneration of damaged sciatic nerve than that of control, and the intensity of injury was a more important factor in the recovery of nerves compared to the duration of injury.