Fitness, Strength Bounce Back After Pregnancy

May 11, 2005 -- Women lose a bit of their fitness and strength during pregnancy and immediately after giving birth. But less than seven months later, they tend to bounce back.

That isn't just true for women who were super fit before pregnancy, say researchers in May's issue of Medicine & Science in Sports & Exercise. The finding was seen in women with lean, average, and heavier prepregnancy bodies.

"Our major findings include decreases in both maximal oxygen consumption (a measure of fitness) and leg strength from pre-pregnancy to six weeks post-partum, with some of these observed decreases recovering by 27 weeks post-partum," write Margarita Treuth, PhD, and colleagues.

Fitness Before Pregnancy

Treuth's study included 17 women with low body mass index (BMI), 34 with normal BMI, and 12 with high BMI before pregnancy. The women were around 30 years old, on average.

They took fitness and strength tests before pregnancy and again at six and 27 weeks after giving birth. The women rode stationary bikes and hit the weight machines, lifting as much weight as possible with their legs and arms.

The group had a wide range of fitness levels before pregnancy, say the researchers.

Pregnancy Changes

Even the strongest, leanest women lost some ground in aerobic fitness and muscle strength during pregnancy and shortly after giving birth. The dip is understandable, given the challenges of pregnancy and early motherhood, say the researchers.

It's not clear when the changes took place, say the researchers. They didn't test any women during pregnancy, for safety's sake.

The decline in fitness and strength wasn't the end of the story. Less than seven months after giving birth, the women had recovered some of the ground they'd lost, the study shows.

It's not that motherhood made anyone buff. Rather, the data showed that pregnancy-related losses in fitness and strength were reversible.

New Priorities

Overall, the women were equally active before and after pregnancy, but their activities changed.

After pregnancy, they walked more and were more active around the house. Meanwhile, they backed off conditioning exercises and water-based activities.

"The reasons for these post-partum changes in activity, fitness, and strength are probably a reflection of the changes in the mother's responsibilities when becoming a parent," write researchers.

Staying Active During Pregnancy

Past generations may have shied away from activity during pregnancy, but that's no longer standard medical advice.

"Experts recommend that pregnant women who have no obstetric or medical problems exercise at least 30 minutes a day," says researcher Margarita Treuth, PhD, in a news release.

"Moderate activity, like brisk walking, will help maintain health and fitness of the changing pregnant body," says Treuth, who works at the Center for Human Nutrition at Johns Hopkins Bloomberg School of Public Health.

"Participation in a wide range of activities appears to be safe; participation in sports with high contact or with an increased risk of falling should be avoided," write researchers. When in doubt, ask a doctor for guidance.

SOURCES: Treuth, M. Medicine & Science in Sports & Exercise, May 2005; vol 37: pp 832-837. News release, American College of Sports Medicine.