The newest guidelines from the American College of Obstetricians and Gynecologists reaffirmed in 2019 suggest a pregnant woman should use her rate of Perceived Exertion (see image below) or the Talk Test.
A pregnant woman’s heart rate fluctuates throughout gestation, therefore making it difficult for you to determine from a number on a heart rate monitor just how hard your body is actually working. As a woman’s heart rate response changes throughout pregnancy, the past overall recommendation was to keep your heart rate to a maximum of 140 beats per minute (BPM) during exercise. This guideline assumed that all pregnant women with a heart rate of 140 BPM are exerting the same amount of effort during physical activity.
In 1985, ACOG conducted a study that resulted in their recommendation of 140 beats per minute as the maximum heart rate for a pregnant woman who is exercising. In 1996, the ACOG rescinded this guideline. As mentioned above, in 2015 ACOG CO 650 [reaffirmed 2019] determined that perceived exertion is a more effective way to monitor intensity than heart rate monitors. While the talk test is another fantastic way to measure exercise intensity during pregnancy! Fun note: If you have are an avid exerciser, you might recognize you are pregnant because your normal routine has your RPE or heart rate going higher than usual.
A handful of research articles (from Dr. James Clapp and the IOC’s Exercise and Pregnancy in Recreational and Elite Athletes) suggest pregnant athletes should use a heart rate monitor as an additional tool because athletes tend to “push” through.
It’s important to pay attention to how hard you are working during pregnancy exercise, or your rate of perceived exertion. Use the Talk Test, speaking a full sentence while exercising. Or the Borg Scale.
Please note that your doctor’s recommendations always supersede this advice. So, if your OB recommends you stay under 140 BPM, then that is the protocol that you should follow.
ACOG recommends the 20-point scale, while other research recommends a 10-point scale. For moderate intensity exercise you should be between 13-14 or “somewhat hard” on the Borg scale.
Measuring exertion through the talk test is one of the easiest ways to determine what’s too much and what’s too little. As long as you can carry on a conversation while exercising you are likely in the sweet spot and not overexerting yourself.
Takeaway: The use of perceived exertion can be a more effective way to determine intensity during pregnancy, unless you are an athlete with longer training sessions – more on that below.
Please see the Prenatal Exercise Do’s & Don’ts before beginning prenatal exercise.
Download our Prenatal & Postnatal Starter Pack.