Effect of test interruptions on blood lactate during constant workload testing

Abstract

Objective: 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). Methods: Nineteen males participated in this study. In experiment A, 1.0 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. Results: 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 (ΔBLC10-30, 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 ΔBLC10-30, and 70% of the variance of P-MLSS and Int-MLSS were explained by TI duration (P < 0.001). Conclusions: TI decreased BLC30 and ΔBLC 10-30 but has no effect on MLSS. Consequently, with TI, the MLSS is achieve(at higher P-MLSS and Int-MLSS.