The specificity of training principle predicts that combining resistance and endurance training (concurrent training) could interfere with the maximum development of strength and endurance capacity that results from either type of training alone.
Purpose: To determine whether endurance and resistance training performed concurrently produces different performance and physiologic responses compared with each type of training alone.
Methods: Untrained male volunteers were randomly assigned to one of three groups: endurance training (ET, N = 12); resistance training (RT, N = 13); and concurrent training (CT, N = 16). The following measurements were made on all subjects before and after 12 wk of training: weight, percent body fat, peak oxygen consumption (V̇O2peak), isokinetic peak torque and average power produced during single-leg flexion and extension at 60 and 180°·s−1, one-repetition maximum (1RM) leg press, 1RM bench press, vertical jump height, and calculated jump power.
Results: Weight and lean body mass (LBM) increased significantly in the RT and CT groups (P < 0.05). Percent body fat was significantly decreased in the ET and CT groups. V̇O2peak was significantly improved only in the ET group. Peak torque during flexion and extension at 180°·s−1 increased in the RT group. Improvements in 1RM leg press and bench press were significant in all groups, but were significantly greater in the RT and CT compared to the ET group. Jump power improved significantly only in the RT group, and no group showed a significant change in vertical jump height.
Conclusions: Concurrent training performed by young, healthy men does not interfere with strength development, but may hinder development of maximal aerobic capacity.