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The Pregnant Woman’s Guide to Running

Prepare your body to run all the way to the delivery room.

While it's safe for women to continue chasing mileage while pregnant, there's not much research on what to expect as a runner who's expecting. “With sports traumas, we have really good guidelines for returning to play. With childbirth, there’s nothing,” says Jessica Zendler, Ph.D., adjunct research assistant professor at the University of Michigan’s School of Kinesiology in Ann Arbor, where she studies pregnancy’s effects on running. “We view childbirth as you would any other major trauma.”

Luckily, the field of pre- and post-natal exercise is gaining more attention. Here, the minds on the front lines share insight on how pregnancy impacts the sport and what women can do to stay on their feet all nine months and beyond.

In the first trimester:

Even the most dedicated athletes often feel significant fatigue starting six to 11 weeks after conception, which can make them choose their beds over the road, explains Samantha Kempner, MD, an assistant professor at the University of Michigan Medical School. 

One physical change that occurs early on is looseness in the pelvic region, or feeling unstable in the hips. That’s due to the hormone relaxin, explains Carolyn Appel, CSCS, New York City-based author of The Little Book for Big Bellies. “Your body produces this chemical right after conception to relax your ligaments,” she says. Down the road, this gives the baby the space it needs to pass through. 

Strength training causes connective tissues to stiffen and counteracts the laxity caused by relaxin,” Appel explains. In the first trimester, prioritize strengthening the legs and core with squats, lunges, bridges, Turkish get-ups, and rows on top of running. These moves can also prevent alignment issues that often come with weight gain.

“To run pain free, you have to be strong enough not only to push off and spring forward, but more importantly, to absorb the forces generated during impact,” she says. (With each step, landing on the ground places four to six times your body weight on your feet.) 

With extra blood pumping to the fetus, heart rate (and the amount of blood that’s pumped with each beat) also increases. This can actually make for a faster runner, “much like blood doping,” Appel says. The benefits of increased blood volume continue throughout pregnancy. In the midst of all the setbacks, athletes can at least bask in this boost.

In the second trimester:
The pelvis tips forward as the belly grows, shifting the center of gravity and changing how the hips move and rotate, Zendler explains. Running will feel physically harder, so women shouldn’t be surprised if they have to cut back on distance.

The impact of running coupled with weight gain can further weaken the pelvic floor muscles, Appel says, leading to another glamorous side effect: Incontinence. It can make postpartum recovery longer and more difficult if it continues, she notes. 

Leaking while running is a sign to stop and focus instead on safe exercises like bird dogs, bridges, and carries to build pelvic floor strength. Holding your breath increases abdominal pressure and the likelihood of developing abdominal separation (a common condition called diastasis recti) and pelvic floor dysfunction, Appel explains. “Exhale during exertion to relieve that pressure.” Avoid crunches, sit-ups, planks, and backbends, which put too much pressure on the pelvic floor.

In the third trimester: 
Some women run all the way to the delivery room, but one study of 110 athletes found that only 31 percent of them continue running in the final leg of pregnancy. 

As the fetus grows, it demands more real estate. That means the lungs don’t have the room to expand as easily, Appel says, so taking deep breaths may feel more challenging. 

The effects of relaxin go into overdrive now, too. The pelvis widens even more and so do the feet. Walking will look more like waddling and women will have to take shorter steps to stay stable, Appel explains. And because the hormone loosens the ligaments, their arches might drop, impacting their gaits. 

“This places a high demand on the legs, especially on the hip abductors,” she says. (The first trimester’s leg training will come in handy here.) 

Focus on maintaining a neutral spine by keeping your ears and shoulders in line with your hips when sitting, standing, and running to combat these changes, Appel says. Gaining the recommended 25 to 35 pounds can also help keep discomfort at bay, she notes. 

If running feels painful, lift instead or opt for low-impact activities like biking, swimming, and yoga. Women can continue doing squats and deadlifts as they get bigger, but they should avoid single-leg moves if they have pelvic pain. It may signal that they don’t have enough strength to stabilize the joint in this position, Appel says. 

Otherwise, single-leg exercises will improve running performance. “It’s a single-leg activity,” she says, and athletes’ training should prepare them for the demands of the sport as much as possible. 

Postpartum: 
“Tissues require plenty of time to heal from childbirth before you stress them again,” Appel says. Start with slow walks as soon as it feels doable. Wait until all vaginal bleeding has stopped, usually after four to six weeks, before returning to any activity of moderate intensity, like strength training, says Appel.

“In order to run again, you have to build up the muscles in your lower body and pelvic floor,” she adds. Try this post-pregnancy workout. A pelvic floor physical therapist can create an individualized plan to help combat diastasis recti or a weak core or pelvic floor.  

She strongly suggests waiting until three months postpartum before lacing up: During this time, hormones are still coursing through the body, the joints are still lax, the uterus has to shrink, skin has to heal, and the pelvic floor needs to recover from labor. It’s a beautiful and traumatizing experience, so it’s important to give the body time to heal.

When running is back on the schedule, women should consider a gait analysis and a new set of sneakers, since their arches may forever be changed, Zendler notes.