Low Back Pain in Pregnancy Linked to Muscle Strains
It’s not the way pregnant women walk as much as it is their overworked muscles that lead to ankle and back pain, researchers say.
The researchers’ 3-D motion analysis indicated the additional weight that pregnant women carry leads to the same overuse strains suffered by athletes.
The study did not find evidence that carrying a baby makes a woman in advanced pregnancy waddle, as many doctors believe. The researchers think the women avoided that by working harder to keep the same gait pattern they had before becoming pregnant.
“All of the variables that describe how the body looks during walking were really pretty normal,” said researcher Theresa Foti of the Motion Analysis Laboratory of Shriners Hospitals for Children in Greenville, S.C. “The ones that were different were the ones that estimate muscle work.”
The researchers looked at 15 women in their 35th to 40th weeks. The women walked about 12 yards with reflective markers at points on their hips, knees and feet while six video cameras recorded changes in position of the markers. Thirteen of the women did the same thing at least one year after giving birth; two did the comparison walks before becoming pregnant.
The scientists examined such factors as pelvic tilt and hip, knee, leg and foot motion when the women were pregnant and when they were not. The researchers used formulas to estimate the strain on calf and hip muscles. The results were reported in the Journal of Bone and Joint Surgery.
The women walked with the same motions pregnant and not pregnant, Foti said. However, the strain on their muscles was higher when they were pregnant, she said.
“We found significant increases at the hip and the ankle, in proportion to the amount of weight gained during pregnancy,” Foti said. This led the researchers to think pains that pregnant women complain about may be related to muscle strain, though the study did not look at pain itself. Pregnant women may be having to work harder to maintain the walking style they had when they were not pregnant, said Dr. Jon R. Davids, a coauthor.
Other experts, however, suggested the women were waddling at times when the researchers were not measuring.
“Pregnant women have abnormal gait; however, the reason is that their muscles get fatigued,” said Dr. Joseph A. Bosco III, chief of orthopedics at Jamaica Hospital Medical Center in New York. “It does occur later in the day.”
And pregnant women undergo changes in their feet that can throw off their gait and create pain, said John Pagliano, a podiatrist in Long Beach. The extra weight of pregnancy makes their arches drop, he said. The dropped arch makes their feet turn in, so women turn their entire legs out to try to stabilize themselves, he said.
All of the experts believed that pregnant women can reduce their risk of pain by building their leg muscles before or in the early stages of pregnancy.
“You are going to be better off the more fit and strong you are before pregnancy,” Foti said. Bosco suggested a program of aerobic exercise, such as walking, and strength exercise, such as weight training. And Pagliano called for stretches, as well as good running shoes and possibly arch supports.
