Comparison of maximal lactate steady state with anaerobic threshold determined by various methods based on graded exercise test with 3-minute stages in elite cyclists

BACKGROUND: The maximal lactate steady state (MLSS) is defined as the highest workload that can be maintained for a longer period of time without continued blood lactate (LA) accumulation. MLSS is one of the physiological indicators of aerobic performance. However, determination of MLSS requires the performance of a series of constant-intensity tests during multiple laboratory visits. Therefore, attempts are made to determine MLSS indirectly by means of anaerobic threshold (AT) evaluated during a single graded exercise test (GXT) until volitional exhaustion. The aim of our study was to verify whether AT determined by maximal deviation (D(max)), modified maximal deviation (ModD(max)), baseline LA concentration + 1 mmol/l (+ 1 mmol/l), individual anaerobic threshold (IAT), onset of blood lactate accumulation (OBLA(4mmol/l)) and V-slope methods based on GXT with 3-min stages provide valid estimates of MLSS in elite cyclists. METHODS: Twelve elite male cyclists (71.3 ± 3.6 ml/kg/min) completed GXT (the increase by 40 W every 3 min) to establish the AT (by D(max), ModD(max), + 1 mmol/l, IAT, OBLA(4mmol/l) and V-slope methods). Next, a series of 30-min constant-load tests to determine MLSS was performed. Agreement between the MLSS and workload (WR) at AT was evaluated using the Bland–Altman method. RESULTS: The analysis revealed a very high (r(s) > 0.90, p < 0.001) correlation between WR(MLSS) and WR(Dmax) and WR(IAT). The other AT methods were highly (r(s) > 0.70) correlated with MLSS except for OBLA(4mmol/l) (r(s) = 0.67). The Bland-Altman analysis revealed the highest agreement with MLSS for the D(max), IAT and + 1 mmol/l methods. Mean difference between WR(MLSS) and WR(Dmax), WR(IAT) and WR(+1mmol/l) was 1.7 ± 3.9 W, 4.3 ± 7.9 W and 6.7 ± 17.2 W, respectively. Furthermore, the WR(Dmax) and WR(IAT) had the lowest limits of agreement with the WR(MLSS.) The ModD(max) and OBLA(4mmol/l) methods overestimated MLSS by 31.7 ± 18.5 W and 43.3 ± 17.8 W, respectively. The V-slope method underestimated MLSS by 36.2 ± 10.9 W. CONCLUSIONS: The AT determined by D(max) and IAT methods based on the cycling GXT with 3-min stages provides a high agreement with the MLSS in elite cyclists. Despite the high correlation with MLSS and low mean difference, the AT determined by + 1 mmol/l method may highly overestimate or underestimate MLSS in individual subjects. The individual MLSS cannot be properly estimated by V-slope, ModD(max) and OBLA(4mmol/l) methods.