Cross-training between cycling and running in untrained females

Objective. The purpose of the study was to evaluate the cross-training response between running and cycling in untrained females. Experimental design. The following study involved a pretest, post-test, 3 x 3 factorial design. Setting. Training (4 days-week^-1, 10 weeks, 70-80% heart rate reserve) occurred at the Center for Exercise and Applied Human Physiology. Exercise testing occurred at the Veterans Hospital, Exercise Laboratory. Patients and participants. Subjects included healthy, untrained females aged 18-25 years, (N = 18). Intervention. Subjects were assigned to one of three (n = 6) training groups (run = R, cycle = C, both run and cycle = RC) matched on pre-training CE V̇O₂max results. Measures. Graded treadmill run (TR) and cycle ergometer (CE) tests were performed on each subject to determine a mode specific V̇O₂max and the lactate threshold (LT). Graded arm ergometer (AE) was performed to determine V̇O₂max and heart rate and blood lactate at 20 and 40 Watts (W). Testing occurred prior to (0T), after 5 (5T) and after 10 weeks of training (10T). Body fat testing (hydrodensitometry at residual lung volume) was performed at 0T and 10T. Results. TR and CE V̇O₂max as well as TR and CE V̇O₂ at the LT improved throughout the 10 weeks, regardless of training group. Although there were no changes in V̇O₂max or blood lactate levels during AE, submaximal heart rates were significantly reduced over the 10 weeks, regardless of training group. Conclusions. These results indicate that the aerobic benefits of either run, cycle or combined run and cycle training are similar in untrained females. The LT and AE heart rate data demonstrate that improvements in V̇Omax due to ten weeks of training are a result of pronounced peripheral and moderate central adaptations.