Blood ammonia and ventilation at maximal exercise

This study, intended to evaluate the role of ammonia (NH3) as a ventilatory stimulus, was conducted in three groups of subjects: 14 sedentary individuals, 12 triathletes, 5 patients with a glycolytic deficiency (Mc Ardle disease). All subjects performed maximal exercise tests on a cycle ergometer. Ventilation measured at maximal oxygen consumption (VE 100%) was correlated with lactatemia (lactate 100%) and ammonemia (NH3 100%) in the sedentary group, but only with ammonemia in triathletes, although NH3 100% and lactate 100% were correlated in both groups, which suggests that correlation between VE 100% and NH3 100% is not a false correlation. In patients with Mc Ardle disease, unable to produce lactate during exercise, VE 100% was correlated with NH3 100%. NH3 may act indirectly by increasing the production of lactate in cereberal tissue. Another hypothesis rests on the fact that the catabolism of ammonia leads to an increase in intracerebral glutamate which may act as a ventilatory stimulus.