Abstract
We studied 11 healthy untrained volunteers (aged 28.9±4.6 years) during 60 minutes
of aerobic ergometric exercise with constant heart rates of 130 to 140 beats/minute.
We found a continuous and significant decrease in systolic and diastolic pressure
from 175±18/77±7 mmHg in the 5th minute to 144±14/68±6 mmHg in the 60th minute of
exercise. Cardiac function and structure were assessed by M-mode echocardiography
before exercise, after 5 minutes and after 60 minutes of exercise at comparable heart
rates. The results demonstrated significant decreases in cardiac Output, ejection
fraction, and diastolic posterior wall velocity and an increase in total peripheral
resistance after 60 minutes of exercise. We conclude that the decrease in blood pressure
during long-term aerobic exercise in healthy untrained subjects might be at least
influenced by a decrease in left ventricular filling and contractility, possibly indicating
cardiac fatigue.
Key words
Cardiac fatigue - cardiac function - aerobic exercise - blood pressure
