Relationships between postcompetition blood lactate concentration and average running velocity over 100-m and 200-m races.

The relationships between anaerobic glycolysis and average velocity (v) sustained during sprint running were studied in 12 national level male sprinters. A blood sample was obtained within 3 min of the completion of semi-finals and finals in the 100-m and 200-m Cameroon national championships and blood lactate concentration ([la-]b) was measured. The 35-m times were video-recorded. The 100-m and 200-m [la-]b were 8.5 (SD 0.8) and 10.3 (SD 0.8) mmol.l-1, respectively. These were not correlated with the performances. Over 200 m [la-]b was correlated with the v sustained over the last 165 m (r = 0.65, P < 0.05). In the 9 athletes who participated in both the 100-m and 200-m races, the difference between the [la-]b measured at the end of the two races was negatively correlated to the difference in v sustained over the two races (r = 0.76, P > 0.02). Energy expenditure during sprint running was estimated from the [la-]b values. This estimate was mainly based on the assumption that a 1 mmol.l-1 increase in [la-]b corresponds to the energy produced by the utilization of 3.30 ml O2.kg-1. The energy cost of running was estimated at 0.275 (SD 0.02) ml O2.kg-1.m-1 over 200-m and 0.433 (SD 0.03) ml O2.kg-1.m-1 over 100-m races. These results would suggest that at the velocities studied anaerobic glycolysis contributes to at least 55% of the energy expenditure related to spring running. However, the influence of both mechanical factors and the contribution of other energy processes obscure the relationship between [la-]b and performance.