Research from the University of Alberta shows that high-intensity interval training is safe for expectant mothers and their unborn children, in contrast to the typical advice for exercising during pregnancy.

Jenna Wowdzia, a master's student in the programme for pregnancy and postpartum health, compared the cardiovascular effects of moderate-intensity continuous training to high-intensity interval training on the mother and foetus.

“What was novel about this study is that we were looking at how the baby responded to high-intensity exercise,” says senior author Margie Davenport, a pregnancy researcher in the Faculty of Kinesiology, Sport, and Recreation.

“We looked at responses in terms of the fetus’s heart rate and also the blood flow that was going to the fetus, so we can see if they were getting enough blood flow, oxygen and nutrients.”

According to Davenport, high-intensity interval training is a popular fitness trend, and an increasing number of people are interested in carrying on with this kind of exercise while pregnant.

For the study, high-intensity exercise consisted of 10 one-minute interval exercises performed at 90 per cent of one's maximal effort or higher, followed by one minute of active recovery. Exercise of moderate intensity was assessed using a 30-minute session.

For the Canadian Society for Exercise Physiology and the Society of Obstetricians and Gynaecologists of Canada, Davenport previously served as the project leader for the preparation of the 2019 Canadian Guideline for Physical Activity During Pregnancy.

Davenport reviewed all the material that was available to determine whether exercise during pregnancy is safe and advantageous for both the mother and the unborn child before creating the guidelines.

“With those systematic reviews and with those guidelines we actually found really impactful information,” says Davenport.

“Engaging in physical activity and exercise during pregnancy is associated with a 40 per cent reduction in the risk of developing major pregnancy complications such as gestational diabetes, pre-eclampsia and gestational hypertension, and there is no negative impact on the baby.”

Early small-scale studies that suggested longer-duration progressive exercise to maximal levels had some potential adverse effects led to a broad recommendation not to exceed 90 per cent of maximal exercise at any point during pregnancy, said Davenport.