Cardiovascular response to cycle exercise during and after pregnancy

Abstract

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)

Maternal Responses to Aerobic Exercise in Pregnancy

“…During submaximal non-weight-bearing exercise, the difference in absolute VO 2 (L/min) between pregnant and nonpregnant women is either unchanged or increased during pregnancy. 12,26,[30][31][32][33][34][35][36][37] In contrast, during weight-bearing exercise the absolute VO 2 (L/min) is elevated further and has been suggested to be related to gestational weight gain. However, when these values are expressed relative to body weight (mL/kg/min) oxygen consumption is lower, similar or slightly higher for a given work rate.…”

Postural effects when cycling in late pregnancy

“…This study also confirmed earlier findings that short duration, moderate intensity cycling is well-tolerated by the mother in either posture. 4,5,16 Most importantly, this is the first report demonstrating that FHR responses to cycling are posture-independent. There were no potentially adverse indicators, such as fetal bradycardia or FHR deceleration to suggest that the babies were at risk.…”

“…Compared with postpartum values, some studies found that cardiac output during pregnancy increases with upright cycling, 3,4 but not with semi-supine cycling. 5 Secondly, does semi-supine exercise have any potential advantages?…”

A study on cardiac autonomic modulation during pregnancy by non-invasive heart rate variability measurement

“…Pregnancy-induced effects on cardiovascular function are increases in heart rate (HR), stroke volume (SV), and cardiac output. [3,4] These changes result from the interactive effects of a primary reduction in peripheral vascular resistance, [5] cardiac autonomic modulation and barorefl ex function that lead to a higher resting heart rate.…”

“…Pregnancy-induced effects on cardiovascular function are increases in heart rate (HR), stroke volume (SV), and cardiac output. [3,4] These changes result from the interactive effects of a primary reduction in peripheral vascular resistance, [5] cardiac autonomic modulation and barorefl ex function that lead to a higher resting heart rate.It is well established that high-frequency (HF) power (0.15-0.40 Hz) of HRV is mediated by parasympathetic nervous system (PNS) modulation and respiratory sinus arrhythmia, [6][7][8] whereas low-frequency (LF) power (0.03-0.15 Hz) refl ects both sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) autonomic infl uences. [8,9] The ratio of low-frequency power to high-frequency power (LF/HF) has been used to refl ect cardiac sympathetic modulation (SNS…”