Hemodynamic Determinants of Maximal Oxygen Intake in Patients with Healed Myocardial Infarction: Influence of Physical Training

Abstract

Fourteen patients with a healed myocardial infarction (no angina pectoris) had maximal oxygen intake (V O O2 max) determinations and hemodynamic studies at submaximal and maximal exercise levels; seven patients were studied two months after an acute myocardial infarction (untrained group) while seven had followed a physical training program for 13.5 months (trained group). At the maximal exercise level, all patients exhibited a fall in stroke volume which was 15% (untrained group) and 18% (trained group) lower than at submaximal exercise level: this decrease in stroke volume, presumably resulting from myocardial ischemia, was the major factor limiting the V o o2 max of the patients. The maximal arteriovenous oxygen (A-V O O2 ) difference of untrained patients was the same (14.4 ml/100 ml) as for healthy subjects. Higher V O O2 max of trained patients (2.50 vs 2.07 liters/min) resulted almost exclusively from greater maximal A-V O O2 difference (16.5 vs 14.4 ml/100 ml); this suggests that long-term physical training increases peripheral extraction of oxygen by the working muscles.