Effect of ramp slope on ventilation thresholds and VO2peak in male cyclists.

Abstract

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.