Schierbauer J; Wolf A; Wachsmuth NB; Maassen N; Schmidt WFJ;

Metabolites [Metabolites] 2023 May 06; Vol. 13 (5).
Date of Electronic Publication: 2023 May 06.

We wanted to determine the influence of total blood volume (BV) and blood lactate quantity on lactate concentrations during incremental exercise. Twenty-six healthy, nonsmoking, heterogeneously trained females (27.5 ± 5.9 ys) performed an incremental cardiopulmonary exercise test on a cycle ergometer during which maximum oxygen uptake (V·O _2max ), lactate concentrations ([La ^– ]) and hemoglobin concentrations ([Hb]) were determined. Hemoglobin mass and blood volume (BV) were determined using an optimised carbon monoxide-rebreathing method. V·O _2max and maximum power (P _max ) ranged between 32 and 62 mL·min ^-1 ·kg ^-1 and 2.3 and 5.5 W·kg ^-1 , respectively. BV ranged between 81 and 121 mL·kg ^-1 of lean body mass and decreased by 280 ± 115 mL (5.7%, p = 0.001) until P _max . At P _max , the [La ^– ] was significantly correlated to the systemic lactate quantity (La ^– , r = 0.84, p < 0.0001) but also significantly negatively correlated to the BV (r = -0.44, p < 0.05). We calculated that the exercise-induced BV shifts significantly reduced the lactate transport capacity by 10.8% ( p < 0.0001). Our results demonstrate that both the total BV and La ^– have a major influence on the resulting [La ^– ] during dynamic exercise. Moreover, the blood La ^– transport capacity might be significantly reduced by the shift in plasma volume. We conclude, that the total BV might be another relevant factor in the interpretation of [La ^– ] during a cardio-pulmonary exercise test.