Comparison of blood lactate concentration between the Biosen C-Line and the Analox GM7 lactate analysers during incremental exercise

Analysis of blood lactate profiles can be used to prescribe training. However, lactate concentration often varies between different lactate analysers, with some analysers measuring higher than others – often dependent on whether the device measures lactate in plasma, whole blood or haemolysed whole blood. This can consequently impact on lactate threshold variables such as onset of blood lactate accumulation (OBLA), the velocity at which could be underestimated or over-estimated, with subsequent training intensities being set too high or low. Therefore, the aim of this study was to determine the level of agreement between two bench-top devices including the Analox GM7 (uses non-haemolysed blood) and the Biosen C-Line (uses haemolysed blood) to determine level of agreement between devices for the measurement of blood lactate concentration and how this impacts running speed at OBLA. Following institutional ethics approval, 10 males and 2 females (mean ± SD: age 21.93 ± 12.30 years, body mass 76.16 ± 8.87 kg, height 79.0 ± 11.08 cm) participated in the study. Each participant performed an incremental treadmill running test using 4-min stages with speed increments of 0.5 km · h−1 . Duplicate capillary blood samples were taken from the fingertip at rest and following each exercise stage for the determination of blood lactate concentration measured using the Biosen C-Line and the Analox GM7; each sample was analysed through each analyser twice. Blood lactate concentration from the two analysers were plotted against running speed for each participant to identify running speed at a fixed blood lactate concentration of 4 mmol · L−1 (OBLA) commonly used in exercise prescription. Although results found a strong linear relationship (Pearson’s correlation) between the lactate concentration (R = 0.901) and speed at OBLA for the two analysers (R = 0.991), a paired t-test showed that the Analox produced significantly lower measures of lactate concentration (P < 0.0001) than the Biosen, and that running speed at OBLA was significantly higher for the Analox compared to the Biosen (mean ± SD: 12.13 1.89 vs. 11.78 1.83 km · h−1 respectively; P < 0.001). The η2 statistic for lactate concentration (0.29) and running speed at OBLA (0.67) indicated a large effect size. In conclusion, the results indicate that the Analox measures blood lactate concentration lower than the Biosen, resulting in OBLA occurring at higher running speeds for the Analox. This has implications on exercise prescription around OBLA – faster (and possibly over-estimated) running speeds would be prescribed from exercise tests that use the Analox GM7 device compared to the Biosen C-line device. Furthermore, the two devices cannot be used interchangeably – the same device should be used for measuring blood lactate in the same athlete