Plasma lactate concentrations for self-selected maximal effort lasting 1 h

Purpose: We determined the plasma lactate concentrations for 11 well-traine d endurance cyclists or triathletes during a laboratory trial to measure ma ximal distance cycled in 1 h. Methods: Subjects performed three distance tr ials, cycling as far as possible in 1 h. Blood samples were taken from a fo reann vein every 10 min during the third trial (T). Samples were analyzed b y spectrophotometer for plasma lactate concentrations ([La]). Results: Duri ng T, subjects cycled 40.8 +/- 2.2 km at an average of 83 +/- 4% of their p redicted maximum heart rate (HRmax). Minimum and maximum [La] for each subj ect was noted for minutes 10, 20, 30, 40, and 50. Minimum [La] ranged betwe en 2.8 and 10.3 mmol.L-1, and maximum [La] ranged between 5.8 and 13.6 mmol .L-1. The average [La] from minute 10 to 50 was calculated for each subject and ranged from 5.0 to 12.3 mmol.L-1. This did not correlate with performa nce (distance covered in 1 h). Therefore, there was a wide range of individ ual plasma lactate responses to the same laboratory test that simulated an actual race. The overall average [La] for all subjects was 7.6 +/- 2.1 mmol .L-1. Conclusions: These data indicate first that the value of 4 mmol.L-1, commonly referred to as OBLA, may often underestimate the upper limit of to lerance to lactate during a maximal endurance performance rest lasting appr oximately 1 h. Second, during this type of work, intersubject differences i n average plasma lactate concentration do not correlate with performance.