Maximum exercise tests on "postcoronary" patients.

The maximum oxygen intake has been measured directly (uphill treadmill walking) in 36 patients following recovery from myocardial infarction. These were selected as follows: 15 consecutive new entrants to an exercise program that is currently accepting about one-sixth of the total reported myocardial infarction hospital admissions in metropolitan Toronto (group A), 12 patients not responding well to training (group B), and 9 patients now running substantial distances (group C). The only clinical complications were two episodes of ventricular tachycardia. Twenty patients reached an oxygen plateau, and in group C, the maximum heart rate (170/min) reached Scandinavian norms, with a maximum oxygen intake (2.63 +/- 0.35 1/min STPD, 36.9 +/- 4.8 ml/kg-min STPD) as in healthy men of the same age. The rate of adaptation to a progressive submaximum test was such that comparable Astrand nomogram predictions of VO2max were obtained from data in the 3rd and 5th min at the third load. Predictions generally agreed closely with directly measured values. It may be concluded that in patients who have recovered sufficiently to enter an exercise rehabilitation program 1) predictions of VO2max have about the same accuracy (+/-10) as in healthy subjects, and 2) direct measurements can often be pursued to an "oxygen plateau" without due risk.