Twenty-five sedentary female volunteers, 18-30 years of age, were studied to determine the effects of an endurance running program on leg strength gains from a weight training program. Subjects were randomly assigned to one of three groups: a weight training group (W), a weight training plus running group (RW), or a control group (C). The subjects trained three days per week, approximately one hour per day, for nine weeks. The RW group ran for 25 min then weight trained for 30 min, whereas the W group weight trained for one hour. Subjects were tested for one-repetition maximum (l-RM) pre-training, at two week intervals during training, and post-training. Thigh girth (midpoint [MG] and 1.18 cm above the patella [AP]) and percent body fat were measured pre- and post-training, only weekly on a calibrated scale. Body weight was measured. Significant improvements in isotonic leg strength of 56% for W and 66% for RW were observed, with no difference between the groups. W and RW also achieved a significantly greater isotonic leg strength than the C group. The experimental groups had a significantly greater posttest AP as compared to the C group. No significant differences were observed over the experimental period in MG, percent body fat and body weight of any of the groups. In conclusion, the running program used in the present study did not interfere with leg strength or girth gains achieved through weight training. These results are in contrast to those reported in other studies which found that aerobic training impaired strength gains. / Master of Science