Differences in Cycling Performance at the Same Blood Lactate Concentration

Abstract

0829 Purpose: The purpose of this study was to investigate the possibility that the same blood lactate (La) concentration can represent different absolute and relative work intensities between recreational cyclists and elite cyclists. A 4 mmol/L blood La was used as the blood lactate concentration marker for both groups. Methods: Nine recreational cyclists and 9 elite cyclists volunteered. Two cycling tests were performed. The first test was an incremental maximal test (electrically-braked cycle ergometer) to determine physiological parameters, specially, heart rate, V02, VE, and blood lactate, and the workload (watts) of the two groups at a blood La of 4 mmol/L. For the second test, both recreational and elite athletes cycled at a fixed workload corresponding to the blood La of 4mmol/L obtained from the first test. This second test was performed to exhaustion by both groups and the time to exhaustion between the two groups determined. Results: During the maximal cycling test, elite cyclists had a significantly higher V02 and power output at both maximal exercise and at the exercise intensity resulting in 4 mmol/L La than did recreational cyclists. The percentage of VO2max at 4 mmol/L blood lactate was significantly greater in elite cyclists compared to recreational cyclists (81 ± 3 vs. 77 ± 6 %; P <0.05). Percentage of maximal power output values at 4 mmol/L blood La was also significantly greater for the elite group compared to the recreational group (80.7% ± 2.8 vs. 75.8% ± 4.4; P = 0.017). In the second test, time to exhaustion obtained at an intensity corresponding to 4 mmol/L La concentration was significantly shorter in the elite group compared to recreational cyclists (15.4 + − 3.2 min vs. 21.3 +- 8.6 min;P = 0.043). This represented a 38 % less time to exhaustion compared to the recreational group (P<0.05). Conclusion: The same blood lactate concentration did not represent the same absolute and relative intensities in elite and recreational cyclists. At the same blood La, recreational athletes were exercising at a lower relative intensity and could sustain work for longer periods of time compared to well-trained elite cyclists. Thus, in the elite group, the same blood lactate concentration represented a higher metabolic stress. This could be due to differences in muscle metabolism with lower lactate exportation to the blood because of more developed oxidative mechanisms, as well as, more developed lactate shuttle mechanisms in the elite cyclists. These results should help coaches and physiologists who prescribe training programs according to blood lactate values.