Six males and seven females trained 3 d per wk (30 min at 80 to 85% heart rate reserve) for 20 wk on a leg press apparatus. A progressive exercise test was administered on a cycle ergometer, leg press apparatus, and treadmill before and after training. Before training, peak oxygen consumption (VO2, ml X kg-1 X min-1) during the leg press test was higher for the males (23.9 +/- 1.60, mean +/- SE) compared to the females (19.5 +/- 2.40, P less than or equal to 0.05). Peak VO2 during the cycling (males = 36.6 +/- 2.65, females = 28.5 +/- 2.35) and treadmill (males = 39.8 +/- 2.04, females = 33.2 +/- 2.64) tests was also different between the sexes, and 30 to 40% higher than during the leg press test (P less than or equal to 0.05). Peak heart rate (beats X min-1) was not different between the sexes (P greater than 0.05), yet was 11% lower during the leg press test (165 +/- 3.5) compared to the cycling (184 +/- 2.8) and treadmill (187 +/- 1.3) tests (P less than or equal to 0.05). After training, peak VO2 during the cycling and treadmill tests increased 10 to 15%, compared to 35% during the leg press test (P less than or equal to 0.05). The only change in peak heart rate was a 6% increase during the leg press test (P less than or equal to 0.05). Although peak VO2 on the leg press apparatus was lower than on the cycle ergometer and treadmill, leg press exercise elicited a sufficient stimulus for increasing peak VO2 on the three testing modes.