4-parameter Model To Analyse The Blood Lactate Response To Short-term All-out Exercise

Abstract

After the termination of maximal short-term high intensity exercise (MSE), the blood lactate concentration (BLC) continues to increase before it starts to decreases, a kinetic based on different dynamic physiological processes. Since the early 1980s the only tool for the non-invasive analysis of the latter is a bi-exponential 6-parameter model, which requires subsequent post-exercise BLC measurements for up to 120 min of rest. PURPOSE To analyse a 4-parameter model describing the BLC response to MSE that requires post-exercise BLC measurements for only 20 min with special respect to MSE-duration. METHODS 11 males (24.6 ± 2.3 yrs; 182.4 ± 6.8 cm; 75.1 ± 9.4 kg) performed MSE lasting 10 s (T1), 30 s (T2) and approx. 3 min (T3), respectively, with BLC measurements immediately before and up to 20 minutes post exercise. The model includes the BLC before exercise, a hypothetical exercise induced intra muscular increase of lactate (A), time constants describing the appearance (k1) and the disappearance (k2) of lactate in the blood compartment. Additionally, it enables to calculate the maximum of the BLC post MSE (BLCmax) and the time when BLCmax occurs (TBLCmax). RESULTS The explanation of variance of the BLC was 97 ± 2% (T1), 98 ± 2% (T2) and 99 ± 1% (T3), respectively. The mechanical energy (T1: 100.6 ± 9.8, T2: 248.0 ± 21.5, T3: 905.5 ± 112.5 J kg−1), A (T1: 9.0 ± 2.1, T2: 14.7 ± 2.1, T3: 19.1 ± 3.3 mmol l−1), BLCmax (T1: 8.6 ± 1.8, T2: 14.1 ± 1.8, T3: 15.1 ± 1.3 mmol l−1) and TBLCmax (T1: 4.4 ± 0.9, T2: 6.1 ± 1.0, T3: 8.7 ± 1.5 min) increased (p <0.05) whilst power output (T1: 10.1 ± 1.0, T2: 8.3 ± 0.7, T3: 4.8 ± 0.5 W kg−1) and k1 (T1: 0.733 ± 0.244, T2: 0.614 ± 0.164, T3: 0.313 ± 0.12 min−1) decreased (p <0.05) from T1 to T2 to T3, respectively. k2 was higher (p <0.05) in T1 (4.05 10−2 ± 1.12 10−2 min−1) than in T2 (2.08 10−2 ± 1.64 10−2 min−1). CONCLUSIONS The 4-parameter model appears to be suitable to analyse the dynamic pattern of the BLC response to MSE. All parameters proved to be sensitive with respect to changes in test duration and corresponding modulations in the exercise intensity. The model seems to provide useful information with respect to the lactate concentration in the blood, in the muscle, and the dynamics of the lactate exchange between both compartments.