Have you ever heard the guideline to “keep your heart rate below 140 beats per minute” during pregnancy? If so, you’re certainly not alone. This outdated guideline dates back to 1985 — and while it was officially eliminated in 1994, it somehow still persists today. So if that guideline isn’t accurate, what should you be following instead? How do you gauge a safe level of exertion during pregnancy? And how do you know which sources to trust? This post answers all of those questions, with evidence-based support to back it up.
Read on to learn:
- What the official pregnancy exercise guidelines are, and who sets them
- Why heart rate is not a reliable measure of exertion during pregnancy
- How to use Rate of Perceived Exertion (RPE) to find the right intensity for your body
- What the Talk Test is and when to use it
Quick Answer: The current guideline from the American College of Obstetricians and Gynecologists (ACOG) is to use Rate of Perceived Exertion (or “RPE”). ACOG eliminated the heart rate guideline in 1994 after research showed that it was not an accurate gauge of exertion during pregnancy for several reasons. RPE relies on listening to your body and gauging your exertion based on how you feel. Using a 1 – 10 scale, working within a 6 – 8 range is generally good for pregnancy (those accustomed to high-intensity exercise may be able to work up to an 8.5). Remember that RPE is based entirely on how you feel, and this will vary greatly by individual and by pregnancy stage.
What are the “Official” Guidelines and Who Sets them?
Currently, there is no global consensus on exercise recommendations during pregnancy. Each country generates its own guidelines. In the United States, the American College of Obstetricians and Gynecologists (ACOG) is the body that provides the official medical guidelines for exercise during and after pregnancy.
ACOG published its very first set of guidelines in 1985, when almost no research existed about exercise during pregnancy. In the absence of data, ACOG set a blanket guideline to “keep heart rate below 140 beats per minute during pregnancy.”
In the years that followed, research showed that heart rate is not an accurate gauge of exertion during pregnancy — and in 1994, ACOG eliminated that guideline and replaced it with the Rate of Perceived Exertion (RPE). RPE relies on listening to your body and gauging your exertion based on how you feel, which is a much more accurate method. This guideline continues today, as reflected in the latest version of the ACOG Guidelines, updated in 2020 (reaffirmed in 2023).
Why Heart Rate is Not a Reliable Measure of Exertion During Pregnancy
The reason why ACOG eliminated the heart rate guideline in 1994 was that research confirmed that it was not a reliable gauge of exertion during pregnancy for several reasons:
- Resting heart rate progressively increases throughout pregnancy
- Heart rate response to exercise is variable throughout pregnancy, and from one individual to another
- Blunted, exaggerated, and normal linear responses may all be seen at different stages during the same pregnancy (ACE, 2011)
So, now that you know why RPE replaced the heart rate guideline, let’s talk more about how to use this tool.
How to Use RPE to Gauge Your Exertion
“Rate of Perceived Exertion” (RPE) is an easy-to-use tool because it’s all about how you feel. While there are different RPE scales, we like to use a 1 – 10 scale because it’s the simplest:
- 1 = Extremely Easy: This is minimal-to-no exertion, like gentle walking.
- 10 = Extremely Difficult: This is maximal exertion, like sprinting or lifting something so heavy you could only do 1 repetition.
In general, a good guideline for pregnancy is to work between 6 and 8 on the RPE scale. This means that on a scale of 1 – 10 (with the parameters noted above), you work in what feels like a 6 – 8 range for you. If you are accustomed to higher intensity exercise, you can go up to an 8.5, provided that it feels ok for you. Please note, however, to follow your doctor’s guidance. There is no research to date at RPE levels higher than 8.5.
It’s important to note that RPE will vary highly by individual — and for each individual at different stages of pregnancy. For example, what feels like a 7 to someone used to high-intensity exercise will feel much higher to someone just beginning their fitness journey. Moreover, what feels like a 6 earlier on in your pregnancy will feel much higher later in pregnancy when you are carrying an additional 25 – 35+ lbs of weight. Finally, given the many fluctuations during pregnancy, your RPE can vary day-to-day. That same set of squats that felt like a 7 on Tuesday might feel like an 8 on Friday!
The final thing to note is that there are other considerations to ensuring the cardio exercise you are doing is safe, such as managing intra-abdominal pressure and alignment shifts. Many traditional cardio moves should be modified as pregnancy progresses. To help you with this, check out these Cardio Modifications for Pregnancy. You’ll find several modifications for the most common cardio exercises — from jumping jacks, to burpees, and more.
What the Talk Test is and When to Use it
You may have heard of using the Talk Test. This is another tool that ACOG references as an option for gauging a safe exertion level. This means you can carry on a conversation while exercising. This can be helpful for those newer to exercise, but if you are well-conditioned, you can stick to the same RPE guidance outlined above: 6 – 8 (or up to 8.5). While working at an “8,” you may not be able to carry on a conversation, but this is still within a safe range to work.
The Bottom Line
Understanding how to gauge a safe level of exertion is one of the most important tools you can have for exercising confidently during pregnancy. RPE puts the focus where it belongs: on how your body feels, rather than an arbitrary number on a monitor. Whether you’re navigating pregnancy yourself or guiding clients through it, this simple tool can make a meaningful difference in how you approach every workout.
Sources:
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ACOG Committee on Obstetric Practice (2020, April). Physical Activity and Exercise During Pregnancy and the Postpartum Period. American College of Obstetricians and Gynecologists. Opinion 804.
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American Council on Exercise. (2011). ACE Group Fitness Instructor Manual: A Guide for Fitness Professionals. San Diego, Print.