Influence of physical exercise on baroreceptor sensitivity during pregnancy

Abstract

BACKGROUND: Baroreceptor sensitivity (BRS) refers to the magnitude of change in the heart rate in response to change in blood pressure (e.g. upon standing). The impact of regular antenatal exercise on maternal BRS is unclear. AIMS: To determine whether supervised weekly exercise influences BRS, and to determine if posture and calculation method are important in antenatal BRS measurement. STUDY DESIGN AND SUBJECTS: Eighty-one healthy pregnant women were randomly assigned to an exercise or control group. The exercise group attended weekly classes from the 20th week of pregnancy onwards. OUTCOME MEASURES: Cardiovascular assessments (beat-to-beat blood pressure, heart rate) were performed at 12-16, 26-28, 34-36 weeks and 12 weeks following birth. BRS was calculated using two methods ("sequence" and "beat-to-beat"). RESULTS: Fifty-one women (63%) completed the study. Mean BRS reduced progressively in all women (p < 0.025) and was lowest in those who exercised (0.046 < p < 0.002). Postnatal increases in BRS were independent of posture. Training-induced BRS (beat-to-beat) reduction occurred earlier than BRS (sequence), and only BRS (sequence) was affected by posture. Heart rate variability reduced with advancing gestation (p < 0.002) and was more pronounced in the exercise group (p < 0.029). CONCLUSIONS: Weekly exercise exaggerated the reductions in BRS and HRV during pregnancy and is likely linked to diminished parasympathetic activity.