Post-competition blood lactate concentrations as indicators of anaerobic energy expenditure during 400-m and 800-m races

Summary The relationships between anaerobic glycolysis and the average velocity (\(\bar \upsilon\)) sustained during running were studied in 17 top level athletes (11 males and 6 females). A blood sample was obtained within 10 min of the completion of major competitions over 400 m, 800 m and 1500 m and the blood lactate concentration [1a]_b was measured. In both male and female athletes [1a]_b was related to the relative performance, as expressed as a percentage of the athlete's best \(\bar \upsilon\) of the season. Over 400m, r=0.85 (P<0.01) and r=0.80 (P<0.05) in males and females, respectively. Over 800 m, the corresponding values were r=0.76 (P<0.01) and r=0.91 (P<0.01). In male runners [1a]_b was correlated to \(\bar \upsilon\): r=0.89 (P<0.01) and r=0.71 (P<0.02) over 400 m and 800 m, respectively. No relationship to relative performance or \(\bar \upsilon\) was obtained over 1500 m. Energy expenditure during competition running was estimated in male runners from the [1a]_b values. This estimate was based mainly on the assumption that a 1 mmol ·l⁻¹ increase in [1a]_b corresponded to the energy produced by the utilization of 3.30 ml·O_kg ⁻¹. The energy cost of running was estimated, by dividing the estimated total energy expenditure by the race distance, at 0.211 ml·kg⁻¹·m⁻¹ over 800 m and 0.274 ml·kg⁻¹·m⁻¹ over 400m. These results suggested that [1a]_b values obtained after the completion of actual competitions can provide an insight into the anaerobic capacity of athletes and data from which the relative contribution of anaerobic metabolism to performance might be inferred, this being more accurate that any laboratory test.