Cardiovascular response to cycle exercise during and after pregnancy.
Our purpose was to determine if pregnancy alters the cardiovascular response to exercise. Thirty-nine women [29 +/- 4 (SD) yr], performed submaximal and maximal exercise cycle ergometry during pregnancy (antepartum, AP, 26 +/- 3 wk of gestation) and postpartum (PP, 8 +/- 2 wk). Neither maximal O2 uptake (VO2max) nor maximal heart rate (HR) was different AP and PP (VO2 = 1.91 +/- 0.32 and 1.83 +/- 0.31 l/min; HR = 182 +/- 8 and 184 +/- 7 beats/min, P greater than 0.05 for both). Cardiac output (Q, acetylene rebreathing technique) averaged 2.2 to 2.8 l/min higher AP (P less than 0.01) at rest and at each exercise work load. Increases in both HR and stroke volume (SV) contributed to the elevated Q at the lower exercise work loads, whereas an increased SV was primarily responsible for the higher Q at higher levels. The slope of the Q vs. VO2 relationship was not different AP and PP (6.15 +/- 1.32 and 6.18 +/- 1.34 l/min Q/l/min VO2, P greater than 0.05). In contrast, the arteriovenous O2 difference (a-vO2 difference) was lower at each exercise work load AP, suggesting that the higher Q AP was distributed to nonexercising vascular beds. We conclude that Q is greater and a-vO2 difference is less at all levels of exercise in pregnant subjects than in the same women postpartum but that the coupling of the increase in Q to the increase in systemic O2 demand (VO2) is not different.(ABSTRACT TRUNCATED AT 250 WORDS)
Sady
S P
SP
Department of Medicine, Miriam Hospital, Providence, Rhode Island.
Carpenter
M W
MW
Thompson
P D
PD
Sady
M A
MA
Haydon
B
B
Coustan
D R
DR
D000328:Adult; D001642:Bicycling; D002302:Cardiac Output; D002320:Cardiovascular Physiological Phenomena; D005260:Female; D006339:Heart Rate; D006801:Humans; D010101:Oxygen Consumption; D049590:Postpartum Period / Q000502:physiology; D011247:Pregnancy / Q000502:physiology*; D013177:Sports; D013318:Stroke Volume; D014655:Vascular Resistance