Objective
To examine the effects of unilateral leg exercise on the contralateral leg and the cross training effect according to the training intensity.

Method
Nineteen healthy males volunteered to be subjects for this investigation and were divided into a training group (N=13) and a control group (N=6). One leg of each subject in the training group was randomly assigned to a six week, three day/week isokinetic strengthening training program for concentric knee extension-flexion performed at 60 degrees/second (group A, N=6) and 180 degrees/second (group B, N=7). The control group did not train for six weeks. The strength of the knee extensor and flexor was tested before and after the six week period training by Cybex 770 dynamometer.

Results
In both groups A and B, the training resulted in significant increase of knee extensor strength in trained limb compared to control group. However, the strength increment of untrained limb was not significant compared to control group.

Conclusion
There was no significant cross training effect following unilateral leg strength exercise.