Is a decrease in arterial pressure during long-term aerobic exercise caused by a fall in cardiac pump function?
Ten healthy normotensive volunteers demonstrated a progressive decrease (p < 0.01) in systolic and diastolic pressures during 1 hour of aerobic exercise. Cardiac function and structure were assessed by M-mode echocardiography before exercise and, at the same heart rate, after 5 minutes of exercise and after 60 minutes of exercise. After 5 minutes of exercise, heart rate, cardiac output, ejection fraction, fractional fiber shortening, and contractility index significantly increased (p < 0.01, p < 0.05, respectively) and total peripheral resistance decreased (p < 0.01) compared with resting values. When compared with the values at minute 5, there was a decrease (p < 0.01) in cardiac output, ejection fraction, fractional fiber shortening, and contractility index (p < 0.05) and an increase (p < 0.05) in total peripheral resistance after 60 minutes of exercise. We conclude that the gradual decrease in arterial pressure seen with prolonged aerobic exercise is the result of a fall in cardiac pump function (as measured by cardiac output, ejection fraction, fractional fiber shortening, and contractility index), possibly indicating cardiac fatigue.)
Ketelhut
R
R
Department of Internal Medicine, Ochsner Clinic, New Orleans, LA 70121.
Losem
C J
CJ
Messerli
F H
FH
D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D002302:Cardiac Output / Q000502:physiology; D004452:Echocardiography; D015444:Exercise / Q000502:physiology*; D005260:Female; D006321:Heart / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D009200:Myocardial Contraction / Q000502:physiology; D013318:Stroke Volume / Q000502:physiology; D014655:Vascular Resistance / Q000502:physiology