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Riding for Two: How to Cycle Safely Through Pregnancy

How much exercise is appropriate during pregnancy? Here are some tips for pregnant cyclists.

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It’s happened—you’ve taken not one, but maybe two or three pregnancy tests and all signs point to yes! After it registers that there’s a teeny-tiny baby forming inside of you, you may start thinking, “I’m an athlete, can I keep doing my sport? How much is too much?”

I’ve been there. I’m a professional mountain biker and I saw the “+ YES” pop up on my pregnancy test last summer.

Here I’ll share the general advice I found to be useful and give you some resources specific to athletes. And I’ll also share what I struggled with, and some tips to make things easier.

Spoiler alert: I was able to mountain bike until the day before my son was born and I was also able to get back on the bike (albeit, riding short and easy) a week after he was born.

General Guidelines—and Do They Apply to Me?

It’s recommended that pregnant women exercise a minimum of three days per week at a moderate intensity for 150 minutes total, or at least 75 minutes of vigorous activity once per week. Exercise during pregnancy is healthy: It can reduce the risk of pregnancy-related illnesses such as depression by at least 25%, and the risk of developing gestational diabetes, high blood pressure, and preeclampsia by 40%. You’ll also hear that you should not start a new activity if you weren’t doing it before you were pregnant. Even medical opinions differ, but my midwife told me she was confident that I knew my body best and if I was doing it before pregnancy, it was probably fine as long as there was no bleeding or big changes to my body.

I was frustrated because I wanted to do the right thing, but I had questions like, how many hours are too many hours of training? Is mountain biking safe while pregnant? Should I avoid exercising outdoors if it’s hot, and how hot is too hot? Is there a max allowable heart rate? How am I supposed to know how hard I can go? As an athlete, you want to continue to do what you love and no one cares more about the developing fetus more than the mother!

Here are four books I recommend for expecting moms:

What I Noticed About Riding While Pregnant

I noticed an increased respiration rate. I knew I was pregnant before even taking the pregnancy test because I was breathing really hard at lower heart rates compared to my normal. Why is that? Increased progesterone makes you need to breathe up to 40-50% more! That doesn’t mean you have to ride at an intensity where you aren’t breathing hard. You will know where you should be. Your body has its own built-in governor that will make it so you simply can’t go harder. I didn’t have the power to get up steep stuff and I would have to walk. I never felt “out of balance.”

I chose not to race because I didn’t feel strong on my bike or like I could access my race pace. Some women have raced while pregnant. You have to use your judgement and do what feels best for you.

Sonya Looney and partner announcing her pregnancy on their mountain bikes in the woods
Photo: Sonya Looney

A Few Myth-Busting Points

1. You don’t have to keep your heart rate under 140. Heart rates vary by individual. For one person, a 140 heart rate may be a basic endurance pace and for another, it could be closer to threshold. Blanket statements about heart rate do not work because a well-trained endurance athlete will have a much different effort level at the same heart rate as an untrained person.

What I did: My body simply wouldn’t let me push too hard when I tried to ride. It’s like when you are fatigued and you just can’t access your top-end turbo. For me, that heart rate was around 150-160, which is at the top of zone 2/low zone 3. I rode where I felt comfortable but I was breathing hard due to progesterone levels. I actually felt the best on my bike during my third trimester.

2. Keep your body temperature lower than 103F. It’s particularly important during the first trimester to avoid hyperthermia and overheating. However, according to Dr. James Clapp, there are some physiological changes that make it harder for you to overheat as your pregnancy progresses. You sweat sooner, dissipate heat easier due to your blood volume, and your body’s setpoint for normal body temperature decreases after the first trimester. “Pregnancy reduces the risk of a mother’s temperature rising high enough to bother the baby by improving her ability to get rid of heat through her skin and lungs,” Clapp says, adding that “a woman who exercises regularly can deal more effectively with heat stress when she is pregnant than when she is not.”

How Hard Can I Go?

There isn’t a lot of information. In Dr. Clapp’s book, it was reported that they did not see fetal distress in fit women who exercised at or above 85% of maximum capacity, but it also did not say how long the women were at that intensity level. Generally, lower intensity is recommended to be around 70% of maximal aerobic power or below. Note that your FTP will likely drop while pregnant (mine did!), so pay attention to RPE (rating of perceived exertion). The guidelines for vigorous activity also seem to vary depending on country.

What About Balance on the Bike and Riding with a Large Baby Bump?

Your body slowly adapts to pregnancy and your increasing size. It’s possible that you’ll feel out of balance. However, for me, I kept mountain biking. The slow change of size did not affect my balance on the bike. I felt more out of balance after having my baby because you suddenly change size and weight.

Falling is not good, so ride within your ability level. Everyone’s technical ability is different and some people had critical commentary about the trails I chose to ride while pregnant. I rode 50-70% slower on the descents and never rode new lines. I only rode down features that I felt very, very confident on. I had no crashes on my bike and didn’t have one close call. I felt more nervous riding the road to the trailhead than on the trail itself.

Riding indoors is safer than riding outdoors, but use your common sense.

Sonya Looney riding her mountain bike while pregnant

Riding Pregnant Might Not Feel Amazing, but It Will Probably Make You Feel Good

I did not feel good or strong when I rode compared to not being pregnant. It’s hard, but I enjoy doing hard things. It’s important to examine your expectations. My expectation was to show up. Show up has always been one of my mantras. Whether you are pregnant or not, there are many days where you’d rather just sit on the couch. Getting started is the hardest part. I’ve always committed to getting started (provided you’re not sick, injured, overtrained, or have pregnancy contraindications.)

Motivation follows action: it’s called behavioral acquisition in psychology, and is often used to treat depression. If I got started and still felt like I wanted to go back to the couch after 15 to 20 minutes of riding, I’d go home. But more times than not, I wanted to keep riding and I just had to get over the activation energy to get started. Sometimes just getting some fresh air in the forest and moving your body makes you feel better, gives you more energy despite feeling lethargic before you started, and helps you maintain a sense of self and control during a time when many things about your body are changing.

Mental Health

Cycling while pregnant or doing whatever sports you love will help you feel more like yourself during a time of uncertainty and many things changing. Avoid comparing yourself to what others are doing. Do what is best for you.

Some women struggle with body image as they gain weight. Try to be excited about healthy weight gain because it means you’re growing a healthy baby.

Losing Fitness with Reduced Volume and Intensity?

I trained 9-10 hours a week while pregnant. I don’t have any data to prove my hypothesis, but I think that training while pregnant strengthens your respiratory system. You have to breathe faster so your muscles get stronger. I also think that your heart is strengthened because it has to increase the stroke volume by at least 10% by the end of the first trimester. That means it has to push more blood out.

According to James Clapp, “Women who continue regular exercise throughout pregnancy and resume it postpartum experience about a 10% increase in their maximal aerobic capacity, even though their exercise volume is uniformly reduced by the added responsibilities of childcare.”

Some Things to Watch Out For

Pubic Symphysis Dysfunction (PSD): I got this from shoveling heavy snow in my driveway and it was really painful for months. Your ligaments get extra stretchy from the hormone Relaxin. When you get PSD, you have pain in your pelvis when your pelvis is not stabilized (pushing a drawer shut with one leg, getting in and out of bed, walking, hiking, etc.).

Diastasis Recti: This happens to a lot of women, so don’t worry or beat yourself up if it does happen. It’s when your abdominals separate down the midline. I didn’t know that I wasn’t supposed to sit straight up in bed to get up. It’s best to roll to your side to get up. It felt like a really painful bruise on the midline of my core. I freaked out and was reading all the worst-case scenarios of the aftermath. I still had it for about a month postpartum and it still felt like a bad bruise. It went away on its own and I haven’t had any problems (for more on this, check out this pelvic floor physio YouTube channel).

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