Ammonium ion and the anaerobic threshold in man

• Published in: Chest Vol. 99; no. 5; p. 1197
• Main Authors: Systrom, D M, Fragoso, C V, Kanarek, D J, Kazemi, H
• Format: Journal Article
• Language: English
• Published: United States 01-05-1991
• Subjects: Ammonia - blood; Anaerobic Threshold - physiology; Double-Blind Method; Exercise - physiology; Humans; Lactates - blood; Lactic Acid; Sodium Glutamate
• ISSN: 0012-3692
• DOI: 10.1378/chest.99.5.1197

To determine if ammonium ion plays a role in the lactate and ventilatory thresholds of incremental exercise, we investigated the effects on blood lactate and ventilation of NH(4+)-buffering by monosodium glutamate. Six normal volunteers underwent intravenous loading with MSG, 9 g, in a randomized, double-blind, saline placebo controlled crossover study. Four of the six subjects had a greater than 10 percent fall in peak (NH4+) following MSG (37 +/- 2.0 vs 25 +/- 4.3 micrograms/dl p = 0.003, PLB vs MSG). When MSG blunted the rise in venous (NH4+) during exercise, uncoupling of the LT and VT was observed. Specifically, with suppression of peak exercise (NH4+) by MSG, the LT was delayed (r = -0.84, p = 0.03), the VT was earlier (r = 0.86, p = 0.02), and the VO2 difference between the LT and VT widened (r = -0.90, p = 0.02). We conclude that NH4+ plays a role in determining the LT and VT of incremental exercise and that the VT may not be exclusively dependent on blood lactate.