Fitness and Lean Mass Increases during Combined Training Independent of Loading Order

Purpose: Although the benefits of combined endurance (E) and strength (S) training for the development of physical fitness and health are well known, scientific examination of the effect of loading order when E and S are combined into the same training session (E+S vs S+E) is rare. This study investigated the effects of moderate frequency E+S versus S+E training on physical fitness, body composition, and blood lipids. Methods: Physically active and healthy young men performed E+S (n = 16) or S+E (n = 18) training 2-3 times a week for 24 wk. Endurance (by incremental bike test) and strength (by dynamic leg press) performance as well as body composition (by dual-energy x-ray absorptiometry), muscle cross-sectional area of vastus lateralis (by ultrasound), and blood lipid levels were determined before and after the intervention. Results: Time to exhaustion, aerobic power (W), and one-repetition maximum strength significantly increased in the two groups at week 24 (E+S, 12%-15%, P = 0.003-0.001; S+E, 16%-17%, P < 0.001), but no between-group difference was observed. Similarly, the two groups significantly increased total lean mass (E+S, 3%; S+E, 3%; both P = 0.001) and muscle cross-sectional area (E+S, 14%, P = 0.001; S+E, 16%, P < 0.001) at week 24 to a similar extent. No significant changes in body fat or blood lipid levels were observed in either of the two groups at week 24. Conclusions: These results showed that moderate-frequency (2-3 times per week) combined E+S or S+E training led to significant improvements in physical fitness and lean body mass but did not induce significant changes in body fat or blood lipid levels. Furthermore, because no between-group differences were observed, these results indicate that loading order does not seem to affect training adaptations of healthy moderately active young men.