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By Dan Nonte, University Relations
Contact: (336) 334-4314
Posted 9-29-09
GREENSBORO, N.C. — Nursing mothers can reduce their bone density loss through exercise, a finding that one day could help protect mothers from osteoporosis later in life, according to researchers at UNCG.
A team led by Cheryl Lovelady, Ph.D., and Laurie Wideman, Ph.D., found that lactating women who exercised during a 16-week span lost 4.8 percent of bone density in their lower spines, while women who didn’t exercise lost 7 percent. The results of the study are published in the October issue of Medicine & Science in Sports & Exercise, the journal of the American College of Sports Medicine.
“To see such a dramatic difference in such a short time was surprising,” said Lovelady, a professor of nutrition. “We are repeating the study with more women and measuring their bone density a year after they give birth.”
Mothers normally lose bone density during lactation, when they are transferring about 200 milligrams of calcium per day from their own stores to breast milk. They typically regain that density when breastfeeding ends.
Lovelady and Wideman want to know whether mothers who reduce density loss through exercise still gain as much density after weaning their babies as women who don’t exercise. If so, exercise could offer a way for mothers to actually increase their bone density from pre-delivery levels and reduce their risk of osteoporosis after menopause. UNCG is enrolling women in a larger follow-up study.
Funded by the N.C. Agricultural Research Service, the study tracked 20 women – 10 who exercised and 10 who did not – during the period from four to 20 weeks after delivery. The women in the exercise group did both resistance and cardiovascular exercises three times per week.
The researchers attributed the reduced density loss to the resistance training, which targeted the lower back during 20-25 minute sessions in the women’s homes with exercise balls, elastic bands and hand weights.
“Obviously if you've just had a baby, you can’t work out the way that you would without a baby,” said Laurie Wideman, an associate professor of kinesiology. “This was training anyone can do in their house, and we still found these significant changes. It was a great finding.”
The research team included nutrition graduate students Melanie Bopp, Heather Mackie and Heather Colleran. Bopp has since earned her doctorate, and Mackie has received her master’s degree. Colleran plans to graduate with her Ph.D. in May.
The follow-up study is recruiting overweight women who plan to breastfeed their babies for at least six months. Those interested in taking part are asked to call (336) 256-1090.
Not surprisingly, the study found other benefits of exercise for new moms. The women who exercised increased their strength and improved their body composition, lowering body fat and increasing muscle mass, even without changes in diet.