3 Prenatal Fitness Myths Busted
Prenatal fitness myths are everywhere these days. And I hear ya - pregnancy information is confusing! Many of the clients I work with share a similar story. You were in a great exercise routine and then - boom you find out you’re pregnant. Suddenly everything feels like it’s changed.
You’re unsure how to modify your workouts safely. Hell, is working out safe at all?
Pregnancy exercise myths are pervasive because this stuff is actually hella confusing!
In this blog post I am going to debunk 3 of the most common myths I hear about exercising during pregnancy,
So let’s get RIGHT to them. Here are my top 3 myths debunked regarding how to exercise safely during pregnancy.
Prenatal Fitness Myth #1: If you haven’t already been exercising don’t start anything new.
This is probably the most common myth that I hear when discussing how to exercise safely during pregnancy. Just the other week I had a new client reach out to me. She wanted to get started on a strength training program because her and her partner were hoping to start trying for a second child in the new year and she knew “she couldn’t start any new exercise routines once she was pregnant”.
In the past few weeks alone I’ve had two new clients express this same concern to me. What happens if I find out I’m pregnant? Can I start exercising?
And while I am a huge advocate for starting an exercise routine at any point (especially if you are planning on getting pregnant anytime soon) if you find out you are pregnant and you don’t have a consistent exercise practice, the second best time to start is now!
Don’t believe me?
In 2019, Canada put out a new set of consensus guidelines for exercising during pregnnacy and one of their top recommendations was that pregnant people should aim to get 150 minutes of moderate intensity exercise per week. Within the population they studied, they looked at a subgroup of folks who were not previously exercising, and the consensus? Still a STRONG recommendation for them to start exercising. Even if they hadn’t been before.
This is because it’s now very much understood that exercise is an incredibly health promoting activity, especially during pregnancy. The benefits are extensive and range from lower chance of metabolic conditions like gestational diabetes and hypertension, lower levels of anxiety and prenatal depression without causing any increase in risk of miscarriage.
Now before we get carried away, like anything you’re going to need to meet yourself where you’re at. If you’ve never strength trained before you’re not going to start by deadlifting 100 lbs regardless on if you’re pregnant or not. Start gradually and progress slowly, listening to the cues your body is giving you. When in doubt, work with a prenatal and postpartum exercise specialist to make sure you’re off to a good start.
Prenatal Fitness Myth #2: Don’t let your heart rate go above x amount (usually 140 bpm)
To understand this one we can go back to its origin which is a 1988 paper looking at fetal heart rate response to maternal exertion. This study found that when a pregnant person raised their heart rate to what they considered maximal levels, fetal heart rate was temporarily affected. When they raised it to submaximal levels (148 bpm or below) fetal heart rate wasn’t impacted. They concluded from this study that raising your heart rate above 148 bpm may result in inadequate fetal gas exchange.
What they didn’t find were any negative effects from this temporary change of heart rate and by 30 minutes later the fetal heart rate was normal again! So it was a temporary, explainable change in fetal heart rate, that didn’t show any negative long term effects on the infant.
But this is where that 140 ish number emerged from.
Since then some research has found the opposite to be true (fetal heart rate elevates as a response to maternal exercise) but in all the research the one consistency is that they have never found that this temporary change in heart rate had any negative effect on the baby.
And not only that, but there might even be some evidence that regular aerobic activity can have a beneficial effect on long term health of baby (review here). You can decide if the evidence seems robust enough to keep you working in a sub-maximal intensity but to me, this evidence doesn’t seem strong enough for a sweeping statement that you should never let your heart rate elevate above 140 bpm.
That all being said, heart rate isn’t actually very reliable way of measuring intensity during pregnancy. During pregnancy, many compounding factors are affecting your heart rate - because every single system in your body is affected by pregnancy. Resting heart rate alone typically increases by 10-15 bpm.
Instead, I recommend using ‘rate of perceived exertion’ as a way to gauge effort level. This is a measurement of how hard you feel like you’re working. And while this sounds incredibly wishy washy, it’s somewhat reliable. It goes something like this: On a scale from 1-10 how hard do you feel like you’re working? Keeping your effort level under 8/10 will keep you in that more ‘sub-maximal’ level.
Prenatal Fitness Myth #3: Avoid any core exercises when you’re pregnant
To be honest, I do feel this myth slowly disappearing which I am so happy to see. Mostly what I hear is just plain old confusion about what is ‘safe’ core work during pregnancy and what is ‘unsafe’ core work during pregnancy.
Here’s my short answer. The amount and specific ways that you’ll have to modify your core work during pregnancy is person specific and has more to do with body readiness, than anything else. Sorry - I know that probably wasn’t what you wanted to hear.
But I won’t leave you hanging. Let’s dig into this a bit more
The main hesitation around core work during pregnancy has to do with the fear that it will cause or worsen pelvic floor symptoms / function OR diastasis recti.
People get really freaked out about diastasis recti - which is a very natural and very brilliant adaptation the body makes to allow the two rectus abdominis muscles (often referred to as the 6 pack muscles) to separate away from each other to make space for the growing baby. This results in the fascia that runs between the two sides to the muscle to spread apart and thin.
You may feel (or maybe see) your abdominals spreading apart and then when you do movements that put pressure on the abdominal wall, get freaked out and worried. So you just avoid doing any core movements at all.
Yes, it’s true that pregnancy causes pressure changes in the body and it can be really useful and helpful to learn good pressure management skills. And this probably requires a few one on one sessions with a professional (psst. HI!). In my opinion, we don’t really have any convincing evidence that bulging or coning in small amounts does long term damage to the core canister system.
For most people, the abdominals will come back together after a few months, for others they will stay slightly separated and this is determined - honestly - primarily by genetics. But if they do remain slightly apart and you’re not having any symptoms or issues then it’s probably fine and you can continue living life as normal. For some, there isn’t enough tension in the tissue between the rectus muscles so creating more tension by strengthening that tissue along with learning good pressure management skills will be really helpful.
Either way core work is during pregnancy will help keep the abdominal wall as strong as possible. You will also want to address your pelvic floor which is part of the entire core system. I really recommended that you see a physiotherapist who specializes in pelvic health. If anyone is looking for one reach out to me, I have a bunch of recommendations for work in person (In Toronto) or virtual.
Core work will likely need to be modified - your capacity to activate your core is going to likely decrease as you move through your pregnancy. But how that happens is very person specific.
Prenatal fitness doesn’t have to be confusing or intimidating. But I get it… it often is!
I have great understanding for how these myths emerge - usually because for every myth there is a grain of truth. And when it comes to pregnancy, we all just want to do what’s best and healthiest for our baby and ourselves.
My intention is to bring an evidence based approach to prenatal fitness and let you decide how you want to run with this information. Remember, your body is resilient and adaptable. If you’re unsure about where to start or how to tailor your workouts, don’t hesitate to seek guidance from a prenatal fitness specialist who can help you move confidently through this wild and wacky time. I’d love to walk with you down this road.
If you’re looking for more individualized fitness support during your pregnancy consider 1:1 personal training.
Click HERE to learn more and apply to work together in person or virtually!
