Modelling the lactate response to short-term all out exercise

BACKGROUND: The maximum post exercise blood lactate concentration (BLC(max)) has been positively correlated with maximal short-term exercise (MSE) performance. However, the moment when BLC(max )occurs (TBLC(max)) 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 (k(1)) and disappearance (k(2)). The 4-parameter model includes BLC at MSE termination and amplitudes and rate constants of increase (A(1), y(1)) and decrease (A(2), y(2)) 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 A(1 )(7.1 ± 1.6 vs. 10.9 ± 2.0 mmol l(-1)) were lower (p < 0.05) in MSE10 than in MSE30. k(1 )(0.610 ± 0.119 vs. 0.505 ± 0.107 min(-1)), k(2 )(4.21 10(-2 )± 1.06 10(-2 )vs. 2.45 10(-2 )± 1.04 10(-2 )min(-1)), and A(2 )(-563.8 ± 370.8 vs. -1412.6 ± 868.8 mmol l(-1)), and y(1 )(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 y(2 )(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.