During her first pregnancy ASICS FrontRunner Jani du Toit was advised to keep her heart rate in check when running, ensuring that she doesn’t over do it, which might lead to somehow harming the baby.

Now, with her second pregnancy and some experience and research into the matter she has realised heart rate itself (and alone) is not an accurate measure of effort (and strain).

“Using heart rate as a measure of exertion might be unreliable in pregnancy because of the many physiological changes that happen in order to support a growing baby. When you’re pregnant, your heart rate, blood volume and cardiac output all increases and because of all these changes, your heart rate may not increase in response to exercise in the same way that it did before pregnancy,” she explains. Her advice (and, as mentioned before, this is purely personal input, she is not a medical doctor): Trying to monitor it, can prove to be false information at times.

Jani du Toit

So, how would you then know if you’re pushing too hard?

“According to my house doctor (and a few other articles I’ve read) the best way to know if you’re ever exerting yourself is to use the ‘talk’ test. Basically, as long as you’re breaking a sweat, raising your heart rate and can talk or carry a normal conversation you’re doing fine!” She says.

Jani still glances at her heart rate monitor though. “It’s kind of drilled into me now, and it still does give me an idea of how hard I’m pushing. What is also a fact is that what might be considered an easy run/exercise for a pregnant mom that ran miles everyday before her pregnancy and a mom that barely ever exercised is two completely different things. So, If you were not exercising or regularly running before your pregnancy then it’s probably not the best time to start a fitness routine while you are pregnant.”

“And, for moms who ran regularly before pregnancy, I’m not saying it won’t be hard – believe me your body is changing – but it is still recommended to continue your exercise routine as much as possible while scaling down, of course.”

According to Jani’s experience, running and other exercise is beneficial to both mom and baby. “Not only can it reduce back pain, promote healthy weight gain during pregnancy, and strengthen your heart and blood vessels, but it may also decrease your risk of gestational diabetes, preeclampsia and cesarean delivery. But everybody’s journey is different, so take yours day by day, and remember, when in doubt – call your doctor!

To learn more, and to find out how to adjust your calculated hear rate zones when pregnant. Read Jani’s blog here.

written by

Jani du Toit

Mother, Blogger and Pattern maker from Pretoria

Age group: 30
Club: ASICS FrontRunner

My Disciplines
Half Marathon Trail 10k

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