Blood ammonia and lactate concentrations during endurance exercise of differing intensities

Axel Urhausen*, Wilfried Kindermann

*Corresponding author for this work

Research output: Contribution to journalArticleResearchpeer-review

16 Citations (Scopus)


The purpose of this study was to examine the changes of blood ammonia concentration ([NH3]b) during endurance exercise of differing intensities on the cycle ergometer and to compare [NH3]b to the changes observed in the simultaneously monitored blood lactate acid concentrations ([la-]b) measurements. A group of 16 endurance-trained athletes participated in the first part of the study and performed exercise of 30 min duration in a randomized order at intensities of 85%, 95%, 100% and 105% of their individual anaerobic threshold (Than,ind; E85-E105) which had been determined beforehand by a cycle exercise test with stepwise increments in intensity. In the second part, 18 average endurance-trained sports students underwent exhausting intensive endurance exercise (IEE) with an intensity of 95% of Than,ind. An extensive endurance exercise (EEE) of the same duration at 85% of the Than,ind was carried out 2 days later. The [NH3]b increased constantly with increasing duration of all exercise. However, [la-]b only increased during exercise with intensities above the Than,ind (E105). The increase of [NH3]b was higher with higher exercise intensities. At IEE, [NH3]b was significantly higher from the 30th min than at EEE, whereas [la-]b increased from the 5th min. In conclusion, [la-]b responded more sensitively to the intensity of exercise than [NH3]b, but it is conceivable that in the future measurements of [NH3]b could be used to advise on the duration of endurance training. At present, however, the lack of experience and lack of appropriate values still hinders the systematic use of [NH3]b measurements in the physiological monitoring of sports training.

Original languageEnglish
Pages (from-to)209-214
Number of pages6
JournalEuropean Journal of Applied Physiology and Occupational Physiology
Issue number3
Publication statusPublished - May 1992
Externally publishedYes


  • Ammonia
  • Endurance training
  • Individual anaerobic threshold
  • Lactate


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