Effect of test interruptions on blood lactate during constant workload testing.

Abstract

To determine whether repetitive test interruptions (TI) during constant load testing influence blood lactate concentration (BLC), maximal lactate steady state (MLSS), MLSS workload (P-MLSS), and relative MLSS intensity (Int-MLSS). Nineteen males participated in this study. In experiment A, 10 subjects (27.5 +/- 2.9 yr; 183.7 +/- 5.2 cm; 77.4 +/- 3.7 kg) performed 30-min constant load tests: one without TI, one with TI of 30 s, and one with TI of 90 s after every 5 min of cycling at a given workload. In experiment B, nine subjects (28.0 +/- 2.7 yr; 182.9 +/- 6.8 cm; 76.2 +/- 4.5 kg) performed 30-min constant load tests at different workloads until MLSS had been determined for all three TI protocols. In experiment A, the BLC after 30 min net working time (BLC30) was higher (P < 0.001) without TI (6.0 +/- 1.3 mmol.l(-1)) than with TI of 30 s (4.9 +/- 1.4 mmol.l(-1)) or 90 s (4.5 +/- 1.1 mmol.l(-1)). The change in BLC during the final 20 min (DeltaBLC10-30) was greater (P < 0.01) without TI (1.2 +/- 1.0 mmol.l(-1)) than with TI of 30 s (0.2 +/- 0.7 mmol.l(-1)) or 90 s (-0.3 +/- 0.7 mmol.l(-1)). In experiment B, the MLSS was not affected, but P-MLSS and Int-MLSS were lower (P < 0.01) without TI (277.8 +/- 24.4W and 73.7 +/- 7.6%) than with TI of 30 s (300.4 +/- 30.4W and 79.2 +/- 8.0%) or 90 s (310.0 +/- 31.2W and 81.5 +/- 7.1%). Approximately 35% of the variance of BLC30 and DeltaBLC10-30, and 70% of the variance of P-MLSS and Int-MLSS were explained by TI duration (P < 0.001). TI decreased BLC30 and DeltaBLC10-30 but has no effect on MLSS. Consequently, with TI, the MLSS is achieved at higher P-MLSS and Int-MLSS.