Influence of age on the hemodynamic response to exercise.

oxygen consumption (VO2), diminished with age. Older subjects had a lower resting cardiac output (Q) than normal subjects, but an identical increase in Q with Vo,. There was no evidence of flattening of this curve as the older subjects approached highest exercise loads. Consequently, the arteriovenous oxygen difference did not increase abnormally on high loads, and the cardiac response to exercise in older subjects appeared to be adequate. The relationship between inspired air volume and heart rate with Vo2 at submaximal loads was not influenced by age. Systolic pressure increased progressively with exercise and showed a greater change in older subjects. Total peripheral resistance at rest increased with age; but with increasing exercise, this difference progressively diminished.