The influence of exercise training on the ventilatory threshold of patients with coronary heart disease

Out of 156 patients with stable coronary heart disease randomized to either an exercise intervention group or a control group, 41 had complete gas analysis data. Continuous gas exchange data, including the ventilatory threshold, and selected heart rates were determined initially and at 1 year. The mean attendance for the exercise group was 2.2 +/- 0.7 days a week at an intensity of 60 +/- 9% of estimated peak oxygen uptake for 1 year of the study. Statistically significant differences (p less than 0.05) were observed between the exercise group (n = 19) and the control group (n = 22) for peak oxygen uptake (L/min), total treadmill time, and supine rest and submaximal heart rates after 1 year. The most remarkable change was a 16% increase in treadmill time. There was no difference between groups for the ventilatory threshold expressed either as an absolute oxygen uptake or as a percentage of peak oxygen uptake at 1 year. However, there was a significant correlation (r = 0.45; p less than 0.05) between the absolute change in peak oxygen uptake and the absolute change in the ventilatory threshold. These results indicate that a moderate exercise program is inadequate to alter the ventilatory threshold in patients with coronary heart disease and that changes in ventilatory threshold do not explain the increase in treadmill time that usually occurs.