Blood glucose responses in humans mirror lactate responses for individual anaerobic threshold and for lactate minimum in track tests

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

The equilibrium point between blood lactate production and removal (La min) and the individual anaerobic threshold (IAT) protocols have been used to evaluate exercise. During progressive exercise, blood lactate [La]b, catecholamine and cortisol concentrations, show exponential increases at upper anaerobic threshold intensities. Since these hormones enhance blood glucose concentrations [Glc]b, this study investigated the [Glc] and [La]b responses during incremental tests and the possibility of considering the individual glucose threshold (IGT) and glucose minimum (Glcmin) in addition to IAT and La min in evaluating exercise. A group of 15 male endurance runners ran in four tests on the track 3000 m run (v 3km); IAT and IGT – 8 × 800 m runs at velocities between 84% and 102% of v 3km; La min and Glcmin– after lactic acidosis induced by a 500-m sprint, the subjects ran 6 × 800 m at intensities between 87% and 97% of v 3km; endurance test (ET) – 30 min at the velocity of IAT. Capillary blood (25 μl) was collected for [La]b and [Glc]b measurements. The IAT and IGT were determined by [La]b and [Glc]b kinetics during the second test. The La min and Glcmin were determined considering the lowest [La] and [Glc]b during the third test. No differences were observed (P < 0.05) and high correlations were obtained between the velocities at IAT [283 (SD 19) and IGT 281 (SD 21) m. · min−1; r = 0.096; P < 0.001] and between La min [285 (SD 21)] and Glcmin [287 (SD 20) m. · min−1 r = 0.77; P < 0.05]. During ET, the [La]b reached 5.0  (SD 1.1) and 5.3 (SD 1.0) mmol · l−1 at 20 and 30 min, respectively (P > 0.05). We concluded that for these subjects it was possible to evaluate the aerobic capacity by IGT and Glcmin as well as by IAT and La min.

Accepted: 25 January 1999