Influence of physical exercise on baroreceptor sensitivity during pregnancy.
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.


OBJECTIVE
To determine whether supervised weekly exercise influences BRS, and to determine if posture and calculation method are important in antenatal BRS measurement.


METHODS
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.


METHODS
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.
a College of Engineering, Swansea University , Swansea , UK.
R E
RE
Carpenter
b Department of Gynaecology , Singleton Hospital , Swansea , UK.
S J
SJ
Emery
c Department of Paediatric Cardiology , University Hospital of Wales , Cardiff , UK , and.
O
O
Uzun
d College of Health and Human Sciences, Swansea University , Swansea , UK.
D
D
Rassi
a College of Engineering, Swansea University , Swansea , UK.
M J
MJ
Lewis
D000328:Adult; D000704:Analysis of Variance; D001794:Blood Pressure / Q000502:physiology*; D016022:Case-Control Studies; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D049590:Postpartum Period / Q000502:physiology; D011247:Pregnancy; D011311:Pressoreceptors / Q000502:physiology*; D055815:Young Adult
Baroreceptor sensitivity; exercise; heart rate variability; pregnancy