Previously we’ve discussed women who ran marathons while pregnant, including a 27-year-old who ran the Chicago Marathon at 39 weeks pregnant, and a 44-year old who ran the Tenzing Hillary Everest Marathon—and won—while three months pregnant with her fourth child.
Doctors said women who were already endurance training before pregnancy may continue as long as it’s not uncomfortable. Even non-marathoners are encouraged to get cardio exercise in, walking at least 30 minutes, five times a week.
But while doctors generally give the same advice about weight lifting—that a woman may continue her pre-pregnancy regimen, as long as it’s not uncomfortable—there is one additional concern.
“The concern is the Valsalva of when you’re holding your breath and you’re really grunting and pushing,” says Dr. James Pivarnik, Director of the Center for Physical Activity and Health at Michigan State University. The Valsalva maneuver is performed by trying to exhale forcefully against a closed airway, like when attempting to equalize ear pressure by closing the mouth, pinching off the nose, then blowing out. Weight lifters often do the same thing, holding their breath to lift heavy objects.
The Valsalva maneuver reduces the heart’s output, briefly reducing blood flow to the body. “It’s not good at any time, but particularly during pregnancy,” Pivarnik says. “When you’re lifting a lot, even if you try not to hold your breath, you almost can’t help it. The concern is it could temporarily impede the blood flow to the fetus, or the blood flow to the mom and she could faint.”
That said, weight lifting is not completely off the table. In fact, there’s some anecdotal evidence that women who lift weights may have an easier time in delivery. “People who lift weights won’t get as tired, and they understand what it feels like to be pushing,” Pivarnik says.
Like with cardiovascular exercise, researchers are a long way off from prescribing acceptable weight training practices during pregnancy because of ethical concerns; they can’t make several thousand pregnant women lift heavy weights to see what it does to their babies.
You’ve surely read about Lee-Ann Ellison. The 35-year old former bodybuilder stirred up national controversy after posting photos of herself lifting heavy weights at a CrossFit gym while eight months pregnant. It’s possible Ellison’s regimen works for her and her baby, because proper pregnancy training can only be determined between each woman and her doctor.
The bottom line: The main concern about weight training while pregnant is breath holding. If you must hold your breath to lift a weight, it’s probably a good idea to back off the poundage until you can breathe easily.