This study examined simultaneous training for strength and endurance during a 13-week, 3-day a week program of hydraulic resistive circuit training and running. Eighteen college males (U.S. Army ROTC) were placed into low resistance (LR; n = 10) or high resistance (HR; n = 8) groups, and 10 college males were controls and did not train. There were 20 exercise stations (7 upper and lower body, and 6 supplementary). LR and HR performed 2 circuits with a work/rest ratio of 20 to 40 s during the 40 min workout. LR trained at two low resistances (approximately 100 cm.s-1), while HR trained at a higher resistance (approximately 50 cm.s-1). Following the workout, subjects ran 2 miles. Pre and post tests included strength, physical fitness, and anthropometry. Strength was assessed with (1) hydraulic resistance dynamometry for 4 exercises at 2 speeds using a computerized dynamometer (Hydra-Fitness, Belton, TX); (2) isokinetic and isotonic upright squat and supine bench press using the Ariel Exerciser (Trabuco Canyon, CA); (3) concentric and eccentric arm flexion/extension at 60 and 120 degrees.s-1 on the Biodex dynamometer (Shirley, NY), and (4) 1-RM free weight concentric and eccentric arm flexion and extension. The fitness tests included 2-mile run, sit-ups, and push-ups. Anthropometry included 3 fatfolds, 6 girths, and arm and leg volume. There were no significant changes in body composition or interactions between the fitness test measures and the 2 training groups (p greater than 0.05). Improvements averaged 15% (run time), 30% (push-ups), and 19% (sit-ups; p less than 0.05). Significant improvements also occurred in 3 of 8 measures for hydraulic testing (overall change 8.8%), in 3 of 4 1-RM tests (9.4%), and in 2 of 8 Biodex tests (6%), but no significant changes for isokinetic and isotonic squat and bench press (1.9%). The change in overall strength averaged 6.5% compared to 16% in a prior study that used hydraulic resistive training without concomitant running. We conclude that gains in strength were somewhat compromised by the simultaneous run training, and that improvements in strength and run performance were independent of LR and HR training intensity.