Effects of High Intensity Interval Training on Pregnant Rats, and the Placenta, Heart and Liver of Their Fetuses

Nils Thomas Songstad,Knut-Helge Frostmo Kaspersen,Ganesh Acharya,Anne Dragøy Hafstad,Kirsti Ytrehus,Purusotam Basnet,Michael Bader

doi:10.1371/journal.pone.0143095

Nils Thomas Songstad, Knut-Helge Frostmo Kaspersen + Show 5 more

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https://doi.org/10.1371/journal.pone.0143095

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Abstract

ObjectiveTo investigate the effects of high intensity interval training (HIIT) on the maternal heart, fetuses and placentas of pregnant rats.MethodsFemale Sprague-Dawley rats were randomly assigned to HIIT or sedentary control groups. The HIIT group was trained for 6 weeks with 10 bouts of high intensity uphill running on a treadmill for four minutes (at 85–90% of maximal oxygen consumption) for five days/week. After three weeks of HIIT, rats were mated. After six weeks (gestational day 20 in pregnant rats), echocardiography was performed to evaluate maternal cardiac function. Real-time PCR was performed for the quantification of gene expression, and oxidative stress and total antioxidant capacity was assessed in the tissue samples.ResultsMaternal heart weight and systolic function were not affected by HIIT or pregnancy. In the maternal heart, expression of 11 of 22 genes related to cardiac remodeling was influenced by pregnancy but none by HIIT. Litter size, fetal weight and placental weight were not affected by HIIT. Total antioxidant capacity, malondialdehyde content, peroxidase and superoxide dismutase activity measured in the placenta, fetal heart and liver were not influenced by HIIT. HIIT reduced the expression of eNOS (p = 0.03), hypoxia-inducible factor 1α (p = 0.04) and glutathione peroxidase 4.2 (p = 0.02) in the fetal liver and increased the expression of vascular endothelial growth factor-β (p = 0.014), superoxide dismutase 1 (p = 0.001) and tissue inhibitor of metallopeptidase 3 (p = 0.049) in the fetal heart.ConclusionsMaternal cardiac function and gene expression was not affected by HIIT. Although HIIT did not affect fetal growth, level of oxidative stress and total antioxidant capacity in the fetal tissues, some genes related to oxidative stress were altered in the fetal heart and liver indicating that protective mechanisms may be activated.

Highlights

Clinical guidelines encourage moderate exercise in pregnancy due to its multiple beneficial effects for both the mother and her offspring [1,2,3]
Expression of 11 of 22 genes related to cardiac remodeling was influenced by pregnancy but none by high intensity interval training (HIIT)
Malondialdehyde content, peroxidase and superoxide dismutase activity measured in the placenta, fetal heart and liver were not influenced by HIIT

Summary

Introduction

Clinical guidelines encourage moderate exercise in pregnancy due to its multiple beneficial effects for both the mother and her offspring [1,2,3]. There is some evidence that physical exercise during pregnancy might mitigate the effects of placental insufficiency or the angiogenic imbalance associated with preeclampsia [5,6]. Regular exercise during pregnancy reduces the risk of having a large for gestation newborn, without a change in risk of having a small for gestation newborn [7], does not negatively affect physical growth or neurodevelopmental outcome at five years and may reduce subcutaneous fat mass in offspring [8]. In pregnant well-trained athletes, exercising for 8 hours per week (range, 3 to 13.5) does not appear to pose any health risk and maximal oxygen consumption (V_ O2max) is maintained throughout pregnancy and post-partum [9]. There remains some concern regarding high intensity training because of possible adverse effect on placental blood flow [10], and guidelines on high intensity training during pregnancy are conflicting [11]

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