Thirty physically active healthy men (20.1 +/- 1.6 yr) were randomly assigned to participate for 10 wk in one of the following training groups: endurance trained (ET; 3 days/wk jogging and/or running), resistance trained (RT; 3 days/wk resistance training), or combined endurance and resistance trained (CT). Before and after training, basal metabolic rate (BMR), percent body fat (BF), maximal aerobic power, and one-repetition maximum for bench press and parallel squat were determined for each subject. Urinary urea nitrogen was determined pre-, mid-, and posttraining. BMR increased significantly from pre- to posttraining for RT (7,613 +/- 968 to 8,090 +/- 951 kJ/day) and CT (7,455 +/- 964 to 7,802 +/- 981 kJ/day) but not for ET (7,231 +/- 554 to 7,029 +/- 666 kJ/day). BF for CT (12.2 +/- 3.5 to 8.7 +/- 1.7%) was significantly reduced compared with RT (15.4 +/- 2.7 to 14.0 +/- 2.7%) and ET (11.8 +/- 2.9 to 9.5 +/- 1.7%). Maximal aerobic power increased significantly for ET (13%) but not RT (-0.2%) or CT (7%), whereas the improvements in one-repetition maximum bench press and parallel squat were greater in RT (24 and 23%, respectively) compared with CT (19 and 12%, respectively). Urinary urea nitrogen loss was greater in ET (14.6 +/- 0.9 g/24 h) than in RT (11.7 +/- 1.0 g/24 h) and CT (11.5 +/- 1.0 g/24 h) at the end of 10 wk of training. These data indicate that, although RT alone will increase BMR and muscular strength, and ET alone will increase aerobic power and decrease BF, CT will provide all of these benefits but to a lesser magnitude than RT and ET after 10 wk of training.