Postural effects when cycling in late pregnancy.
OBJECTIVE
This study assessed if upright cycling is preferable to semi-recumbent cycling during pregnancy.


METHODS
Healthy women with low risk singleton pregnancies were tested at 34-38 weeks gestation. They cycled for 12 min, either semi-recumbent (45 degrees, n = 27) or upright (n = 23), at 135-145 beats min(-1).


RESULTS
When semi-recumbent, minute ventilation was greater (p<0.03) at rest and systolic blood pressure and pulse pressure were greater during exercise (p<0.05). Exercise maternal heart rate, oxygen consumption, oxygen consumption per kilogram, minute ventilation, cardiac output, stroke volume, mean and diastolic blood pressures and arterio-venous oxygen difference were posture-independent. All increased with exercise (p<0.01), except stroke volume when semi-recumbent (p>0.05). Small post-exercise fetal heart rate increases (by 8 beats min(-1), p<0.05) were similar in both postures (n = 11 in each sub-group), with no adverse changes. Fetal heart rate accelerations and uterine activity (n = 11 in each sub-group) were not influenced by posture or exercise.


CONCLUSIONS
(1) Neither posture had a distinct advantage. (2) Both postures were safe for short duration cycling. (3) The same target maternal heart rates are suitable for both postures because they resulted in similar oxygen consumptions and fetal heart rates.
O'Neill
Maureen E
ME
Cardiovascular Research Department, Royal North Shore Hospital, Pacific Highway, St. Leonards, NSW 2065, Australia.
Cooper
Karen A
KA
Boyce
E Stewart
ES
Hunyor
Stephen N
SN
D001642:Bicycling / Q000502:physiology*; D015444:Exercise / Q000502:physiology; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006340:Heart Rate, Fetal / Q000502:physiology*; D006801:Humans; D008176:Lung Volume Measurements; D010101:Oxygen Consumption; D011187:Posture; D011247:Pregnancy / Q000502:physiology; D011263:Pregnancy Trimester, Third / Q000502:physiology*; D012007:Rectum