Comparison of lactate measurements from earlobe and fingertip capillary blood using Biosen S-Line and lactate scout analyzers.

Purpose: This study aimed to compare variations between the earlobe and fingertip sampling sites in exercises dominated by upper body muscle exertion. It also sought to investigate capillary blood lactate differences between Lactate Scout 4 (LS4) and a bench-top analyzer (Biosen S-Line analyzer, BSL) during Double Poling.

Methods: Blood samples were collected from the earlobe and fingertip immediately before exercise, at the end of each of five stages, and at 1-, 3-, 5-, and 7-min post-exercise. Forty healthy university students participated as volunteers. During the study, they performed double poling on a ski ergometer with progressively increasing load. Lactate levels were measured using both the BSL and LS4 analyzers.

Results: Fingertip Bla values were significantly higher than earlobe values, with a mean bias of -0.66 mmol/L, reaching -0.86 mmol/L in the 4-8 mmol/L range. At the earlobe, the highest CCC between BSL and LS4-a was 0.84 (> 8 mmol/L), and for BSL and LS4-b, it was 0.85 (> 8 mmol/L). At the fingertip, the highest CCC between BSL and LS4-c was 0.68 (> 8 mmol/L), and for BSL and LS4-d, it was 0.52 (> 8 mmol/L). Comparing LS4-a and LS4-b at the earlobe, the highest CCC was 0.83 (0-4 mmol/L). At the fingertip, comparing LS4-c and LS4-d, the highest CCC was 0.68 (> 8 mmol/L).

Conclusions: Blood lactate concentrations are higher at the fingertip than the earlobe during SkiErg double poling. The LS4 is less reliable, especially at the fingertip, so using the earlobe with the BSL analyzer is recommended for accurate measurements.