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This study investigated the effect of 10 W*min(-1) (Slow ramp, SR), 30 W*min(-1) (Medium ramp, MR) and 50 W*min(-1) (Fast ramp, FR) exercise protocols on assessments of the first (VT1) and second (VT2) ventilation thresholds and peak oxygen uptake (VO(2)peak) in 12 highly-trained male cyclists (mean +/- SD age = 26 +/- 6 yr). Expired gas sampled from a mixing chamber was analyzed on-line and VT1 and VT2 were defined as two break-points in 20-s-average plots of pulmonary ventilation (V(E)), ventilatory equivalents for O(2) (V(E)/VO(2)) and CO(2) (V(E)/VCO(2)), and fractions of expired O(2) (F(E)O(2)) and CO(2) (F(E)CO(2)). Arterialized-venous blood samples were analyzed for blood-gas and acid-base status. VO(2)peak was significantly lower (p < 0.05) for SR (4.65 +/- 0.53 l small middle dot min(-1)) compared to MR (4.89 +/- 0.56 l *min(-1)) and FR (4.88 +/- 0.57 l *min(-1)) protocols. CO(2) output and blood PCO(2) were lower (p < 0.05), and V(E)/VCO(2) was higher (p < 0.05), above VT1 for SR compared to MR and FR protocols. No significant differences were observed among the protocols for VO(2), % VO(2)peak, V(E), plasma lactate ([La(-)]) and blood hydrogen ion concentration ([H(+)]), and heart rate (HR) values at VT1 or VT2. The work rate (WR) measured at VT1, VT2 and VO(2)peak increased (p < 0.05) with steeper ramp slopes. It was concluded that, in highly-trained cyclists, assessments of VT1 and VT2 are independent of ramp rate (10, 30, 50 W*min(-1)) when expressed as VO(2), % VO(2)peak, V(E), plasma [La(-)], blood [H(+)] and HR values, whereas VO(2)peak is lower during 10 W*min(-1) compared to 30 and 50 W*min(-1) ramp protocols. In addition, the WR measured at VT1, VT2 and VO(2)peak varies with the ramp slope and should be utilized cautiously when prescribing training or evaluating performance.

Maximal oxygen uptake (VO2max) and the ventilatory threshold (Tvent) were measured during cycle ergometry (CE) and treadmill running (TR) in a group of 10 highly trained female triathletes. Tvent was defined as the VO2 at which the ventilatory equivalent for oxygen increased without a marked rise in the ventilatory equivalent for carbon dioxide. Female triathletes achieved a significantly higher mean (+/- SE) relative VO2max for running (63.6 +/- 1.2 ml.kg-1.min-1) than for cycling (59.9 +/- 1.3 ml.kg-1.min-1). When oxygen uptake measured at the ventilatory threshold was expressed as a percent of VO2max, the mean value obtained for TR (74.0 +/- 2.0% of VO2max) was significantly greater than the value obtained for CE (62.7 +/- 2.1% of VO2max). This occurred even though the total training time and intensity were similar for the two modes of exercise. Female triathletes had average running and cycling VO2max values that compared favorably with maximal oxygen uptake values previously reported for elite female runners and cyclists, respectively. However, mean running and cycling Tvent values (VO2 Tvent as%VO2max) were lower than recently reported values for single-sport athletes. The physiological variability between the triathletes studied and single-sport athletes may be attributed in part to differences in training distance or intensity, and/or to variations in the number of years of intense training in a specific mode of exercise. It was concluded that these triathletes were well-trained in both running and cycling, but not to the same extent as female athletes who only train and compete in running or cycling.

Gender differences in maximal accumulated oxygen deficit (MAOD) were examined before and after 4 and 8 wk of high-intensity interval training. Untrained men (n = 7) and women (n = 7) cycled at 120% of pretraining peak oxygen uptake (VO2 peak) to exhaustion (MAOD test) pre-, mid-, and posttraining. A posttraining timed test was also completed at the MAOD test power output, but this test was stopped at the time to exhaustion achieved during the pretraining MAOD test. The 14.3 +/- 5.2% increase in MAOD observed in men after 4 wk of training was not different from the 14.0 +/- 3.0% increase seen in women (P > 0.05). MAOD increased by a further 6.6 +/- 1.9% in men, and this change was not different from the additional 5.1 +/- 2.3% increase observed in women after the final 4 wk of training. VO2 peak measured during incremental cycling increased significantly (P < 0.01) in male but not in female subjects after 8 wk of training. Moreover, the accumulated oxygen (AO2) uptake was higher in men during the posttraining timed test compared with the pretraining MAOD test (P < 0.01). In contrast, the AO2 uptake was unchanged from pre- to posttraining in female subjects. The increase in MAOD with training was not different between men and women, suggesting an enhanced ability to produce ATP anaerobically in both groups. However, the increase in VO2 peak and AO2 uptake obtained in male subjects after training indicates improved oxidative metabolism in men but not in women. We conclude that there are basic gender differences that may predispose men and women to specific metabolic adaptations after a period of intense interval training.