Exercise is good for you, this we know. Too much of a good thing is no good, this we also know. So what’s the rule for exercise during pregnancy? Most of you have heard that it’s safe to continue to do whatever you were doing beforehand, modifying as needed. Some of you may have heard to keep your heart rates below 80% of your heart rate max (HR max).
Exercise during pregnancy helps prevent gestational diabetes, helps with weight management of the mother, and enhances psychological well-being. There are studies that show it can also benefit the fetus both in the short and long term.1
That’s all well and good for the average pregnant woman, but what about the well-trained female athlete?
Female athletes are often pushing 70-100 miles of running, 150+ miles of cycling, 3-4 grueling strength training sessions per week plus drills and core work daily. Call me crazy, but in my personal and professional opinion, that sounds like a bit much for my pregnant clients.
And it is.
The American College of Obstetrics and Gynecologists put out a Committee Opinion in 2015, and was reaffirmed in 2017, that says pregnant women should be encouraged, or work up to, exercising 20-30 minutes of moderate intensity exercise on “most or all days of the week”.2 PREACH ACOG! The statement also includes that few cases of high risk pregnancies require strict bed rest and women should be encouraged to ambulate to tolerance in most cases.
Again, what’s a well-trained athlete to do?
Well, most every woman who has been pregnant will tell you that during the first trimester, they feel like crap. Most well-trained athletes can tell that they’re pregnant simply by how they feel during a workout. I knew I was pregnant before the test turned positive because, very suddenly, my 5 mile runs felt like 15 miles and my easy run pace felt like a death march. I was two weeks pregnant.
It was one week after that I was supposed to run a marathon but ran the half instead.
So, reducing volume and intensity in the first trimester often happens by self-selection. Good! Your body is making more blood cells, a human, a placenta, and blood vessels. Slowing down would be a good call right about now.
But when you hit the second trimester and are feeling energetic, what’s off limits?
Short of scuba or sky diving, hot yoga/pilates, hot tubs, and sports where you might fall or be kicked in the stomach, NOTHING is off limits. Healthy pregnant women can run, do yoga, lift, cycle, swim, dance, or do any other safe form of exercise. But athletes accustomed to high volumes of exercise need to reduce the volume and intensity.
Prolonged and/or chronic dehydration, for one. Dehydration can lead to a decrease in amniotic fluid, overheating, pre-term labor, or even birth defects. Women experiencing Braxton-Hicks contractions may be due to dehydration or overexertion. And that can lead to for-real labor way too early.
The other reason to reduce the volume and intensity of exercise is because is might divert blood flow from the placenta and/or change the flow of blood in the uterine blood vessels. Studies have shown no significant difference in uterine blood flow during 30 minuets of vigorous exercise3, but no one has tested 90+ minutes of vigorous exercise. And most of the scholarly papers I read agreed women training at high levels of sports should be closely monitored during their pregnancy if they intend on training above and beyond the recommended levels of exercise.
Because well-trained athletes are accustomed to training at an extreme level, they must also decreased their volume and intensity exponentially as compared to the average pregnant woman. A reduction by 25% is massive for someone running 70 miles a week (-17.5 miles) versus someone running 25 miles a week. (-6.25 miles).
For the well-trained athlete, it’s fine to keep exercising, even occasionally at a high intensity. But you will never hear me tell a woman I think it’s ok to run a marathon while pregnant. There are too many things that can go wrong during a pregnancy, why risk it? Run those easy 5, keep up with your favorite indoor cycling class, go to your favorite strength training class and modify the moves as your belly grows or situation dictates. Hit up your pelvic floor PT for modifications, strength-building routines, and recommendations for safe classes near you. By all means, KEEP MOVING!
But maybe lay off the IronMan training and back-to-back marathons until you’re fully healed from birth and have been cleared by your friendly women’s health PT. That’s my professional opinion.
- Hopkins, Sarah A.; Cutfield, Wayne S. Exercise in Pregnancy: Weighing Up the Long-Term Impact on the Next Generation. Exercise & Sport Sciences Reviews. July 2011. Vol 39, Issue 3(120-127). doi: 10.1097/JES.0b013e31821a5527
- Physical Activity and Exercise During Pregnancy and the Postpartum Period. Replaces ACOG Committee Opinion No. 650. Obstet Gynecol. 2015 (reaffirmed 2017); 99:171–173. [PubMed: 26595585]
- Szymanski LM, Satin AJ. Exercise during pregnancy: fetal responses to current public health guidelines. Obstet Gynecol 2012;119:603–10.