DETERMINATION OF LACTATE INFLUX RATES INTO ERYTHROCYTES AFTER MAXIMAL EXERCISE
Patrick Wahl1,2,3, Sebastian Frese2, Christoph Zinner1, Edward Lenzen2, Joachim Mester1,3, Wilhelm Bloch2,3 1
Institute of Training Science and Sport Informatics, German Sport University Cologne, Germany Department of Cellular and Molecular Sport Medicine, Institute of Cardiovascular Research and Sport Medicine, German Sport University Cologne, Germany 3 German Research Center of Elite Sport, German Sport University Cologne, Germany 2
Abstract Aim: The purpose of the study was to investigate the maximal lactate influx rate of erythrocytes (RBC) under physiological conditions. Methods: The effects of short term maximal cycling exercise on lactate distribution between plasma and RBC during recovery were investigated. Twelve elite cyclists performed a 30 s lasting maximal‐effort exercise on a cycle ergometer adjusted to an isokinetic mode. Blood samples were taken before exercise, directly after and in minute‐intervals during recovery to determine lactate concentrations [La] in whole blood, plasma and RBC. Results: The congestion of lactate per time unit in plasma exceeded the lactate influx capacity of RBC causing a significant decrease in the RBC‐to‐plasma lactate concentration ratio ([La]RBC/[La]plasma) from 0.54 ± 0.04 before exercise to 0.32 ± 0.03 directly after exercise. The maximal lactate influx rate of RBC was 1.64 ± 0.45 mmol*L‐1 in 30 s. If we assume a linear development of RBC [La] in the first minute we get an increase of 3.28 ± 0.45 mmol*L‐1*min‐1. Discussion: The decrease in ratio is the consequence of a delayed and limited lactate transport across the RBC membrane. The influx rate of RBC is dependent on the plasma‐to‐RBC lactate concentration gradient, the RBC/plasma lactate concentration ratio and the permeability of the membrane (density of lactate transporters). Conclusion: Especially in competitive sports with maximal effort and short duration lactate/H+ flux rates of different tissues might set a limit for performance. Thus, the knowledge about lactate flux rates during and after exercise is essential. The measurement of the RBC influx rate and the RBC/plasma [La] ratio after a maximal exercise test might by a simplified method to determine changes in the lactate transport across the RBC membrane in vivo. However, further comparative studies and experiments in vitro are needed to verify this approach.
Keywords: Lactate transport rate, Blood compartments, Erythrocytes, Maximal cycling exercise, Elite athletes
© German Research Center of Elite Sport Cologne 2010