Pregnant Women Can Workout Without Monitoring Their Heart Rate (Seriously!)

It’s frightening how many so-called certified professionals in the fitness space are unaware of the latest research when it comes to pregnant women and exercise. And that goes double for OBGYNs! For decades women were told to carefully monitor their heart rate while exercising. The underlining idea was that vigorously exercising could potentially cause a miscarriage. Next time someone tells you that remind them that Serena Williams won a record-breaking Grand Slam title while pregnant.

It turns out that the latest research shows that if you exercised regularly before pregnancy, there’s no need to focus on your heart rate. That said, you always want to make sure you get the OK from your doctor – just make sure that your doctor is up-to-date on the latest research.

To find out more about heart rate during pregnancy and intense workouts, we spoke with Nancy Anderson, the CEO and founder of Nancy Anderson Fit and Move Your Bump.

Momtastic: Is it important to monitor your heart rate when pregnant? 

Nancy Anderson: No, normal pregnant women don’t have to keep their heart rate below 140 beats per minute during exercise. There’s really no data to back up this long-standing myth, which likely had its origins in a time when doctors and scientists—knowing very little about pregnancy exercise—erred on the side of caution when it came to physical activity recommendations for pregnant women.

These days we DO know more about pregnancy exercise and based on decades of research the ACOG explicitly advises expecting women to perform at least 20 to 30 minutes of moderately intense exercise every day. Because the benefits for mom and baby FAR outweigh the risks in normal pregnancies. ACOG also says that women who are already fit and used to vigorous exercise are free to continue exercising this hard, up to an hour per day.

Now, if one is a staying below 140 BPMs naturally in your moderately intense exercise… that’s totally ok. But to arbitrarily keep women out of the 140+ heart rate zone is unnecessary and scientifically unfounded. If anything, we think it’s detrimental because it may deter some women from working out hard enough or at all, out of fear of getting their heart rate up too much.

It’s also quite possible that short bouts of vigorously intense exercise is safe and beneficial for most pregnant women regardless of their prior fitness level.  We just don’t have enough data yet to make this kind of general recommendation, so in the meantime we here at MYB will stick to ACOG’s recommendations.

The ACOG, expecting women with normal low-risk pregnancies, regardless of their fitness level, should workout almost every day, at least at a moderately intense level. This includes aerobic exercise and strength training. If an OB/GYN advises otherwise, it’s either because exercise is contraindicated for that individual woman OR because the OB isn’t aware of the updated ACOG protocols, which we have seen in research to be over 50% of them.

Momtastic: If heart rate is no longer considered relevant, what do you suggest instead?

Nancy Anderson: The ACOG recommends an exercise program that leads to an eventual goal of moderate-intensity exercise for at least 20–30 minutes per day on most or all days of the week. Moderate-intensity exercise, ratings of perceived exertion should be 13–14 (somewhat hard) on the Borg ratings of perceived exertion scale. For athletes, vigorous-intensity exercise completed throughout and into the third trimester appears to be safe for most healthy pregnancies.

Some patients, OBGYNs and other obstetric care providers are concerned that regular physical activity during pregnancy may cause miscarriage, poor fetal growth, musculoskeletal injury or premature delivery. For uncomplicated pregnancies, these concerns have not been substantiated. 

Momtastic: What about women worried about exercise causing ab separation?

Nancy Anderson: Diastasis recti is a normal occurrence in pregnancies, the reason why it does not spontaneously heal for everyone can be based off of many factors: movement patterns, previous dysfunction, muscle imbalances, motor skill issues, genetics, posture, scar tissue and more. The separation of the abs is not what we want to focus on, the integrity of the linea alba is and how functional mom is. You can “close your gap” all day long very easily, but that does not mean you have corrected the dysfunction.  This is why every mom should work with qualified experts that can customize a post-natal core and pelvic floor healing program for each body to give mom what her body needs to achieve full healing, that goes way, way beyond measuring her “gap” or ab separation.

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