Caracterização da curva do lactato sanguíneo e aplicabilidade do modelo Dmax durante protocolo progressivo em esteira rolante

Abstract

Purpose: To characterize the blood lactate ([La]) behavior along a progressive protocol on treadmill, and to investigate the applicability of the Dmax model in detecting the lactate threshold (LT) and the sportive performance. Methods: Twenty-seven male athletes of regional level performed the Heck et al. protocol (1985) incremented every 3 minutes. The sportive output was attained by the mean velocity of the 10 km-test. The first and second LT were determined through visual analysis of the [La] (LTv1 and LTv2) curve, and by interpolation of the velocity related to the 2.0 and 3.5 mmol.l-1 concentrations (LT2.0 and LT3.5). The Dmax model has identified the LT in measured values (DmaxMED), and was predicted by the polynomial functions (DmaxPOL), the 2-segment linear (DmaxSEG) and the continuous exponential (DmaxEXP). The characteristic of the blood lactate along the incremental test was checked through 2-segment linear adjustments and continuous exponential. Results: There was no significant difference between the sums of the square residues of the curve adjustments, but there was a trend for a better continuous exponential adjustment at 70.4% of the sampling. Although there was no significant difference between the Dmax MED, DmaxPOL, DmaxSEG, and DmaxEXP, the Dmax methods were higher than the LTv1, lower than the LT3.5, and were not different of the LT2.0. Every Dmax criteria were significantly lower than the mean velocity of the 10 km-test. Conclusions: While the [La] trended to an exponential increase along the progressive protocols on treadmill, the Dmax model presented evidences of its applicability to detect the LT, but not for the sportive output.