The Use Of Different Anticoagulants In Test Tubes In The Determination Of The Lactate Threshold

Abstract

PURPOSE The first purpose of this study was to investigate the differences among the use of different anticoagulants in test tubes for the analysis of blood lactate concentration. A second purpose was to determine the influence of these agents in the determination of various definitions of the lactate threshold. METHODS Eleven trained collegiate runners and eight well-trained competitive cyclists (age: 26.0 ± 1.8 yrs; height: 177.8 ± 1.6 cm; weight: 70.8 ± 1.6 kg; body fat 8.7 ± 0.9%; Vo2max: 59.6 ± 1.6 ml·kg−1·min−1) completed a single continuous incremental maximal exercise test to determine their individual lactate profile. During the maximal exercise test, oxygen consumption, heart rate, and blood lactate were measured. Blood samples were collected at rest, post-warm-up, at the end of each exercise stage and at maximal exercise through a venous catheter placed in an antecubital vein. Each blood sample drawn was analyzed without any treatment or placed in test vials containing potassium oxalate (PO) or lysing agent. A two-way ANOVA with repeated measures (blood treatment × stages) was used to determine differences among test tubes during each stage of the maximal exercise test. A one-way ANOVA was used to determine statistical differences between different test vials at each lactate threshold definition. RESULTS Blood lactate concentration was significantly increased with increased exercise intensity. At rest and low exercise intensities there was no significant difference among test tubes. However, at higher exercise intensities lactate concentration in tubes containing PO and lysing agent were significantly (p <0.05) higher compared to untreated whole blood. Despite these differences, the exercise intensities associated with the various lactate threshold (LT) definitions (breakpoint, 1 mM above baseline, 2.5 mM, 4.0 mM, Dmax method and log-log transformation model) were not significantly (p >0.05) different among test tubes. CONCLUSIONS These results indicate that the use of potassium oxalate and lysing agent, as anticoagulants in test tubes, does not influence the determination of various lactate threshold definitions. However, significantly higher lactate concentrations indicate the need of using a correction factor especially if blood samples are placed in vials containing anticoagulants for later analysis. Supported by Central Washington University's Seed Grant Program