european college of sport science

Thursday, June 25th, 2009
LACTATE RELEASE IN EXHALED BREATH CONDENSATE AT REST AND DIFFERENT LEVELS OF EXERCISE IN YOUNG AND
HEALTHY SUBJECTS
MAREK, E., VOLKE, J., HAWENER, I., MÜCKENHOFF, K., MAREK, W., PLATEN, P.
RUHR-UNIVERSITY BOCHUM
Background: Traditionally, lactate is measured from arterialized earlobe blood samples. Currently developed micro enzyme detectors
permit a non-invasive measurement of lactate in exhaled breath condensate (EBC). This method might be interesting for the combined
use with spirometric measurements of O2 consumption and CO2 release. In order to get inside into the correlation of lactate concentration
or lactate release in EBC and in lactate blood concentrations, we investigated both parameters at rest and at different levels of exercise
in a group of young and healthy subjects.
Methods: The study group 16 healthy subjects consists of 7 females and 9 males (23.3 ± 1.5 years, 175 ± 8,4 cm height, 68.9 ± 9.2 kg
body weight). During resting conditions as well as at 60%, 75%, and 90% of maximal work capacity (each lasting for 5 minutes) on a cycle
ergometer 100 L exhaled air along with capillary blood samples from the earlobe were collected under stationary load conditions. EBC
was obtained by cooling the exhaled air volume to -20°C. The condensates were analysed using an ECo-Check amperometer (Viasys
Health Care). Lactate measurements were performed using a bi-enzym-sensor after lactate oxidase induced oxidation of lactate to
pyruvate and H2O2. The rates of expiratory release of lactate in nmol/min were calculated from the concentrations of lactate in the EBC,
the EBC volume and the time of collection. A functional relation of lactate release and lactate concentration of arterial blood was computed.
Results: At rest lactate concentration in arterialized blood was 0.92 ± 0.31 mmol/L. At a resting ventilation of 12.0 ± 3.8 L/min, collection
time (Ts) for 100 L exhaled air, was 8.9 ± 2.6 min, and 1.86 ± 0.66 ml EBC were obtained. In EBC lactate concentration was 24.5 ± 9.4
µmol/L, lactate release rate was 4.8 ± 1.8 nmol/min.
At 90% maximal work capacity (external load 200 ± 20 Watt), blood lactate concentration increased to 8.4 ± 1.6 mmol/L and ventilation
increased to 83.8 ± 16.0 L/min. EBC collection time decreased to 4.7 ± 2.1 min (p