Kinetics of VO(2) in professional cyclists.

PURPOSE: To analyze the kinetics of oxygen uptake (VO(2)) in professional road cyclists during a ramp cycle ergometer test and to compare the results with those derived from well-trained amateur cyclists.

METHODS

Twelve professional cyclists (P group; 25 +/- 1 yr; maximal power output (W(max)), 508.3 +/- 9.3 watts) and 10 amateur cyclists (A group; 22 +/- 1 y; W(max), 429.9 +/- 8.6 watts) performed a ramp test until exhaustion (power output increases of 25 watts x min(-1)). The regression lines of the VO(2):power output (W) relationship were calculated for the following three phases: phase I (below the lactate threshold (LT)), phase II (between LT and the respiratory compensation point (RCP)), and phase III (above RCP).

RESULTS

In group P, the mean slope (Delta VO(2):Delta W) of the VO(2):W relationship decreased significantly (P < 0.01) across the three phases (9.9 +/- 0.1, 8.9 +/- 0.2, and 3.8 +/- 0.6 mL O(2) x watts(-1) x min(-1) for phases I, II, and III, respectively). No significant differences (P > 0.05) were found between phases I and II (P > 0.05) in group A, whereas Delta VO(2):Delta W significantly increased in phase III (P < 0.01), compared with phase II (10.2 +/- 0.3, 9.2 +/- 0.4, and 10.1 +/- 1.1 mL O(2) x watts(-1) x min(-1) in phases I, II, and III, respectively). The mean value of Delta VO(2):Delta W for phase III was significantly lower in group P than in group A (P < 0.01).

CONCLUSION

Contrary to the case in amateur riders, the rise in VO(2) in professional cyclists is attenuated at moderate to high workloads. This is possibly an adaptation to the higher demands of their training/competition schedule.