Gender Differences in Blood Ammonia Response during Exercise

Abstract

In order to test for possible gender differences in blood ammonia accumulation during exercise, groups of young, physically active women (n = 8) and men (n = 8) performed an incremental load (until exhaustion) and a constant load (30 min at 75% V̇O₂ peak) treadmill exercise test. The groups were matched for physical activity habits. V̇O₂ peak was significantly higher in males (55.8 ± 2.6 ml/kg/min) than in females (44.5 ± 2.8 ml/kg/min). During the incremental exercise test to exhaustion blood ammonia concentration progressively increased with increasing workload in both groups. Blood ammonia concentration was significantly higher in males at 70, 80 and 90% of V̇O₂ peak. Peak blood ammonia concentration was higher in males than in females (155 ± 35 vs 136 ± 67 µmol/l, respectively), but the difference did not reach the level of statistical significance. During the constant load exercise test blood ammonia concentration increased in both groups. At the end of the exercise blood ammonia concentration was significantly higher in males than in females (137 ± 42 vs 91 ± 24 µmol/l, respectively). In conclusion, the blood ammonia concentration during submaximal exercise is dependent on gender, the males showing higher ammonia concentrations compared to females at the same relative workload (percent of V̇O₂ peak).