[Anaerobic threshold: its non-invasive evaluation and relation to exertion tolerance in patients with stenocardia].

The study of changes in gas exchange, lactate and acid-base balance in 36 trained patients with angina pectoris on effort, functional class II and III during spiroergometry has demonstrated that: 1. Ventilation equivalent by oxygen is the most informative and reproducible gas exchange variable during identification of the anaerobic threshold. 2. Anaerobic threshold in patients with low exercise tolerance is reached earlier and at lower oxygen consumption (0.92 +/- 0.02 l/min) than in patients with average exercise tolerance (1.5 +/- 0.06 l/min). 3. In all the cases anaerobic metabolism activation was accompanied by the development of signs of subendocardial myocardial ischemia, which indicates that the basic cause of anaerobic threshold reduction in trained patients was deteriorated cardiac pump function during the onset of myocardial ischemia.