I’ve been a runner for several years, mostly training for and competing in distance events (my favorites being 15ks and half marathons). When I became pregnant with my first daughter, I knew I wanted to continue running, but wasn’t sure of any risks or benefits that would be associated with it. I had friends who ran up to their 40th week of pregnancy, and I was hoping that could be a goal of mine as well.
There are quite a few myths out there about exercising while pregnant. I’ve heard many (older) fitness instructors say pregnant women should not get their heart rate above 140 (not true). I’ve also heard that abdominal exercise should be avoided and that running can be too jarring for the baby (both also not true). The American College of Sports Medicine recommends exercising while pregnant because there are so many proven benefits. Of course, it’s important to be safe. The safe level of exercise depends on the fitness level of the mama.
Right before I became pregnant with Carli I ran my fastest marathon to that date. I had been training hard all fall, and already had a 15k and half-marathon under my belt (both were PRs for me at the time). I’m a prime example that strenuous training does NOT make you infertile, and I found out I was pregnant with her 3 weeks after the marathon. My body was already in great shape from all the training I had done that fall, so I was able to continue running at about the same speed and distances. Instead of keeping a watchful eye on my heart rate monitor, I exercised at the intensity I felt comfortable at. Some days that was a 7:30 min/mile pace. Other days it was closer to a 9 min/mile pace. Some days I had to stop and take walking breaks, other days I could run 8 miles continuously. The bigger my belly grew, the slower my pace and distances became. Once I hit about 25 weeks I started using a belly support band during runs. This not only kept my belly more comfortable but it also lifted some of the strain off my back.
By the time I was 35 weeks pregnant with Carli I was still running 4-5 days per week, with 5-6 miles being the longest distance I could cover. My last week of pregnancy I was able to run 3-4 miles maximum, and ended up running 3 miles the day I went into labor with her.
As a runner, one of the best benefits to maintain my running while pregnant was the effects it had on my fitness level post-partum. Even though I was training at much shorter distances and speeds, my body had to learn to be more efficient at transporting oxygen to my working muscles and the baby. Studies have shown that a person’s VO2 max can actually increase when exercising while pregnant, and this definitely proved to be true once I was able to start running again post-partum. I ran my fastest 5k when she was only 3 months old (I didn’t start running again until she was about 7 weeks old). I ran a personal best half-marathon when she was nine months old and beat my marathon time by 5 minutes when she was 19 months old. The crazy thing was, I wasn’t training as hard as I was before I got pregnant- I didn’t have the time to! I really think that my fitness level just improved over the course of my pregnancy, and I was able to maintain that once I started running again.
With this pregnancy, I’ve been incorporating more strength training. I’m horrible about resistance exercises, in fact, I HATE them. I can run all day long but I hate picking up a dumbbell. Because I wasn’t weight lifting much before I got pregnant, I don’t push myself in this area. There are a few total body conditioning type classes at my gym, which focuses mainly on light weights and a lot of repetition. One class I absolutely love and plan on sticking with it until the baby comes. I’m not overly straining myself, but I’m also building muscle in areas other than just my legs which feels nice.
Something else I’m doing that I didn’t with my first pregnancy is more abdominal exercises. I’m not trying to have a six-pack form immediately after she’s born, but mainly to build strength in my core which can be beneficial for labor and recovery. If there is core work in a fitness class I’m attending, I do have to modify it at times. Doing a full sit up (from laying to sitting position) can put too much strain on the ab muscles and cause them to tear.
Here’s some encouraging evidence about exercising while pregnant from the IOC, based on a systemic review of studies:
- There is little risk of abnormal response in the baby’s heart rate when exercising at <90% of maximal heart rates in the second and third trimesters.
- Baby’s birthweight is less likely to be excessively high, but also not a greater risk for being at a low birth weight
- Exercise does not increase the risk of preterm birth.
- Exercise during pregnancy does not increase the risk of induction of labour, epidural anesthesia, episiotomy or perineal tears, forceps or vacuum deliveries.
- There is some evidence that the first stage of labor (before full dilatation) is shorter in exercising women.
- Exercise throughout pregnancy may reduce the need for caesarean section.
- Exercising while pregnant can decrease risk of developing gestational diabetes or preeclampsia
- Exercise can reduce maternal weight gain
- Exercise enhances psychological well-being (something that has been crucial for me this pregnancy- those hormones have been extra crazy this time around!)
So yes, exercise (in elite athletes, even strenuous exercise) is safe during pregnancy. I have gotten some disapproving looks or looks of shock from some when I’m out running with my big ol’ belly. I know it probably seems weird to some people. But as long as I’m listening to my body, I know both me and my baby are safe.