Left ventricular response to submaximal exercise in endurance-trained athletes and sedentary adults.
This investigation examines the hypothesis that athletes increase stroke volume with submaximal exercise through an augmentation of left ventricular (LV) end-diastolic volume and a reduction of LV end-systolic volume, whereas sedentary adults only increase stroke volume modestly, because LV end-diastolic volume does not increase. Upright bicycle exercise was performed by 17 endurance-trained male athletes and 15 sedentary men. M-mode echocardiograms were obtained during submaximal exercise at predetermined heart rates. Athletes, at a heart rate of 130 beats/min, increased their stroke volume 67% from 72 +/- 18 ml to 120 +/- 26 ml (p less than 0.001). This resulted from an increase of LV end-diastolic volume from 119 +/- 23 to 152 +/- 28 ml (p less than 0.001) and a reduction in LV end-systolic volume from 46 +/- 14 to 31 +/- 9 ml (p less than 0.001). Sedentary men at the same heart rate increased stroke volume 22% from 63 +/- 15 to 77 +/- 21 ml (p less than 0.05). LV end-diastolic volume did not change (96 +/- 20 vs 97 +/- 28 ml) (p = not significant), but LV end-systolic volume decreased (33 +/- 11 vs 20 +/- 9 ml) (p less than 0.001). In conclusion, athletes increased cardiac output through a more prominent augmentation of stroke volume than sedentary subjects at submaximal exercise. This was accomplished through an augmentation of LV end-diastolic volume. This may have a conserving effect on myocardial oxygen consumption at these levels of exercise.
Schairer
J R
JR
Henry Ford Heart and Vascular Institute, Detroit, Michigan 48202.
Stein
P D
PD
Keteyian
S
S
Fedel
F
F
Ehrman
J
J
Alam
M
M
Henry
J W
JW
Shaw
T
T
D000328:Adult; D002302:Cardiac Output; D002306:Cardiac Volume; D004452:Echocardiography; D015444:Exercise; D006339:Heart Rate; D006801:Humans; D008297:Male; D010807:Physical Endurance; D013177:Sports; D013318:Stroke Volume; D016277:Ventricular Function, Left