Blood ammonia response during incremental and steady-state exercise in military staff

Although in the last few years it has been possible to determine blood ammonia, its application in coaching practice has not yet been fully established. This study was designed to evaluate the blood ammonia response to a laboratory incremental exercise test and three steady-state field tests.

There were 26 military personnel who performed a submaximal and maximal exercise test on a treadmill, and a field test which included three different constant velocity stages. Gas exchange parameters were monitored throughout the maximal test. Capillary blood samples were obtained from fingertips during the submaximal and field tests for the determination of ammonia and lactate.

The ammonia threshold was detected in 23 subjects (88.5%) during the submaximal test. No significant differences were found between the ammonia and lactate thresholds which were shown to be significantly correlated. Blood ammonia levels showed a progressive increase during the last two stages of the field test while lactate levels remained stable at less than 4 mmol x L(-1).

The steady increase in blood ammonia concentration recorded in the field test suggests the possibility of using blood ammonia levels to monitor the duration of exercise although further investigation is required to explore this possibility. Moreover, the assessment of blood ammonia levels during incremental exercise protocols confirms the existence of an ammonia threshold, defined as the intensity of exercise at which ammonia shows a progressive increase.