Physiological and metabolic responses of late pregnant women to 40 min of steady-state exercise followed by an oral glucose tolerance perturbation.

We examined the physiological and metabolic responses of 24 active late pregnant women to 40 min of vigorous (95% ventilatory threshold) steady-state treadmill exercise followed by a metabolic perturbation [oral glucose tolerance test (OGTT), 75 g] after exercise. Heart rate and respiratory measures were taken throughout exercise, and blood samples were collected during exercise and every 30 min during the 2-h OGTT. Values were compared with those for a group of physically active nonpregnant women (n = 16) in the luteal phase of the menstrual cycle. Although late pregnant women were heavier, they performed the same work rate (182 vs. 208 W, P > 0.05), with the same oxygen pulse, but responded to the exercise with a blunted heart rate and relative oxygen consumption, with less carbon dioxide expired, possibly due to pregnancy-related adaptations in heart efficiency. Resting glucose concentrations were the same between groups, but by 40 min of exercise (3.8 ± 0.1 vs. 4.6 ± 0.1 mmol/l) and into 15 min of recovery (4.3 ± 0.2 vs. 5.0 ± 0.1 mmol/l), glucose concentrations were diminished in late pregnant women (P ≤ 0.05, respectively). The pregnancy-induced delay of glucose uptake was seen in response to the postexercise OGTT compared with the nonpregnant women, but insulin sensitivity (ISI) remained (7.4 ± 0.9 vs. 9.7 ± 1.4 ISI, P > 0.05, respectively), with the preservation of the sensitivity of lipolysis inhibition of nonesterified free fatty acids to insulin. These adaptations may be fetoprotective, because our research suggests that 40 min of continuous treadmill exercise is well tolerated by physically active pregnant women. No adverse effects on birth outcome (3.53 ± 0.08 kg birth weight; 39.6 ± 0.33 wk gestational age) were observed.

Bed-rest exercise, activity restriction, and high-risk pregnancies: a feasibility study.

This feasibility study investigated the response of maternal heart rate, blood pressure, and uterine contractions to a 30-min bed-rest exercise session (while listening to music) in hospitalized women with varying diagnoses of high-risk pregnancy. Eleven antenatal women who were hospitalized for activity restriction were assigned randomly to either a bed-rest exercise and music group (n = 6) or a bed-rest and music group (n = 5) that involved no exercise. The key findings were that there were no changes in maternal blood pressure or in the number of uterine contractions following the exercise intervention. A supervised bed-rest exercise intervention may, therefore, provide minimal risks and help alleviate the physiological effects of hospital activity restriction.

VO2peak prediction and exercise prescription for pregnant women.

PURPOSE: The present study was designed to develop and validate a prediction equation for peak oxygen consumption VO2peak) using a progressive treadmill test and to refine the current target HR exercise guidelines for pregnancy (PARmed-X for Pregnancy). METHODS: One hundred fifty-six women between 16 and 22 wk of gestation performed the test to volitional fatigue (peak exercise test). Data from every fourth subject were used to form the cross-validation group. The women were separated into two age groups; 20-29 (N = 60) and 30-39 (N = 96) yr of age and then further separated into fit (VO2peak at the top 25th percentile), unfit (VO2peak at the bottom 25th percentile), and active (between these two ranges). HR and VO2peak values were used in the regression equation to predict target HR ranges at 60 and 80% VO2peak. RESULTS: The prediction equation (R2 = 0.72, R2adjusted = 0.71 and SEE = 2.7) was compared with cross validation (N = 39; P = 0.78). Fit women had a VO2peak > or = 27.2 mL.kg(-1).min(-1) and > or = 26.1 mL.kg.min for ages 20-29 and 30-39 yr, respectively, representing the top 25th percentile. Unfit women had a VO2peak of < or = 21.0 mL.kg(-1).min(-1) and < or = 19.6 mL.kg(-1).min(-1), respectively, representing the bottom 25th percentile. HR/VO2peak regression lines for each fitness level were used to generate the target HR zones in each age group. CONCLUSION: This is the first study to provide a validated prediction equation of VO2peak for pregnant women using a progressive treadmill exercise test. The defined target HR zones based on age and the appropriate fitness levels can be used for exercise prescription in healthy pregnant women.