Blood sampling during continuous running and 30‐second intervals on a treadmill

The aim of the study was to investigate whether results from lactate threshold tests on a treadmill would be influenced by collecting blood during 30‐s intervals (INT) as compared to sampling during continuous running (CONT). Ten well‐trained middle‐ and long‐distance runners ran the two protocols randomly on separate days, with the same speed both times. Values of blood lactate, heart rate and ratings of perceived exertion (RPE) were compared. The results showed no significant difference in any of the variables comparing the two regimens. During CONT and INT, running speed at 4.0 mmol · l−1 was 18.6 (±1.2) and 18.7 (±1.2) km · h−1, HR 182 (±10.7) and 183 (±8.1) beats · min−1, respectively. Also at the 2 and 3 mmol · l−1 level there were no significant differences in running speed or heart rate. RPE values of legs and breathing at the final speed, just above the 4 mM level, showed no significant difference. It is concluded that, for well‐trained middle‐ and long‐distance runners, any of the two regimens can be chosen without affecting the lactate threshold results.