Modelling the lactate response to short-term all out exercise.

Abstract

Background: The maximum post exercise blood lactate concentration (BLCmax) has been positively correlated with maximal short-term exercise (MSE) performance. However, the moment when BLCmax occurs (TBLCmax) is rather unpredictable and interpretation of BLC response to MSE is therefore difficult.

Methods: We compared a 3- and a 4-parameter model for the analysis of the dynamics of BLC response to MSEs lasting 10 (MSE10) and 30 s (MSE30) in eleven males (24.6 +/- 2.3 yrs; 182.4 +/- 6.8 cm; 75.1 +/- 9.4 kg). The 3-parameter model uses BLC at MSE-start, extra-vascular increase (A) and rate constants of BLC appearance (k1) and disappearance (k2). The 4-parameter model includes BLC at MSE termination and amplitudes and rate constants of increase (A1, y1) and decrease (A2, y2) of post MSE-BLC.

Results: Both models consistently explained 93.69 % or more of the variance of individual BLC responses. Reduction of the number of parameters decreased (p < 0.05) the goodness of the fit in every MSE10 and in 3 MSE30. A (9.1 +/- 2.1 vs. 15.3 +/- 2.1 mmol l-1) and A1 (7.1 +/- 1.6 vs. 10.9 +/- 2.0 mmol l-1) were lower (p < 0.05) in MSE10 than in MSE30. k1 (0.610 +/- 0.119 vs. 0.505 +/- 0.107 min-1), k2 (4.21 10-2 +/- 1.06 10-2 vs. 2.45 10-2 +/- 1.04 10-2 min-1), and A2 (-563.8 +/- 370.8 vs. -1412.6 +/- 868.8 mmol l-1), and y1 (0.579 +/- 0.137 vs. 0.489 +/- 0.076 min-1) were higher (p < 0.05) in MSE10 than in MSE30. No corresponding difference in y2 (0.41 10-2 +/- 0.82 10-2 vs. 0.15 10-2 +/- 0.42 10-2 min-1) was found.

Conclusion: The 3-parameter model estimates of lactate appearance and disappearance were sensitive to differences in test duration and support an interrelation between BLC level and halftime of lactate elimination previously found. The 4-parameter model results support the 3-parameter model findings about lactate appearance; however, parameter estimates for lactate disappearance were unrealistic in the 4-parameter model. The 3-parameter model provides useful information about the dynamics of the lactate response to MSE.