CORVALLIS, Ore. - A new Oregon State University study has found that postmenopausal women who participate in a long-term fitness regimen that includes jumping and "resistance" exercises using weighted vests can prevent significant bone loss in the hip.
In some cases, the researchers say, the bone density of elderly women who participated in the OSU study actually increased. Results of the five-year study have been accepted for a forthcoming issue of the Journal of Gerontology: Medical Sciences.
The findings are significant because they suggest that exercise can provide a natural alternative to estrogen and other supplements for women seeking to prevent bone loss after menopause, said Christine Snow, director of the Bone Research Laboratory at OSU and principal investigator in the study.
The exercise program developed by Snow already was shown to be effective in helping the elderly reduce their risk of falls by improving their strength and balance. Those improvements, coupled with the new study results on halting bone loss, suggest that the number of hip fractures - estimated at 300,000 annually in the U.S. alone - could be significantly curtailed.
"The evidence is persuasive that the right kind of exercise can play a role in the slowing of bone loss in postmenopausal women," Snow said. "The women themselves are pretty excited about it."
The OSU study, which focused on bone density in the hip, found that the loss of bone by the exercise group was much less in the trochanter region and in total hip measurements than that of the control group, and that bone density actually increased in the femoral neck of the hip. The femoral neck is the site for more than 50 percent of all hip fractures in the U.S.
Overall, the control group lost 3.8 percent of total hip bone mass during the five years of the study while the exercise group lost less than 1 percent. The control group lost 3.4 percent bone mass in the trochanter compared with 0.2 percent for the exercise group. At the femoral neck of the hip, the control group lost 4.4 percent of its bone mass, while the exercisers gained more than 1.5 percent.
"That, of course, is really exciting," Snow said. "These kinds of results from an exercise routine haven't been achieved before and they contradict what the medical community has been saying for years. One important aspect of the study is its longevity. When we checked these women after nine months, the results for bone mass weren't significant.
"After five years, though, the improvement was significant," she added. "Exercise was as good or better than either estrogen or Fosamax for preventing bone loss."
Snow, who is emerging as a leading national authority on the effects of exercise on osteoporosis, has conducted several studies that show the benefits of weight-bearing exercise on bone density in children and younger adults.
No previous studies, however, have extended such benefits to postmenopausal women after this length of time.
In the OSU study, a group of women with an average age of 66 years at the start of the study participated in an exercise program for five years. The program included three sessions a week, which featured a series of "resistance" exercises wearing vests weighted with one to 10 pounds, including squats, lunges, stepping up and down, and getting in and out of a chair.
In addition, they would jump - without weighted vests - about 50 times a day, three days a week. "The key," Snow said, "is to jump comfortably in the air - probably no more than four or five inches - and land flat-footed to distribute the force. The subjects had to have sufficient knee, ankle and hip strength and stability provided by the weighted vest resistance exercise before we would allow them to participate, but no one had any problems."
The results were noticeable to the participants even before they were evaluated.
Barbara Black, a Corvallis resident, was 74 years old when she began the study and has stayed with it ever since. Closing in on her 80th birthday, she is acknowledged as one of the group's most fervent participants. And no wonder - her bone density has actually increased 15 percent with the study.
"Before I started the program, my bone density was below average," Black said. "And, at my age, I certainly expected to be losing more. To actually gain bone is really fantastic. It's been a great motivation. I think you need to keep moving as you age, otherwise you won't be able to.
"You don't have to go downhill," she added with a laugh. "This shows you can go uphill, too." Another study participant is Pat Coolican, 71, who loads a bit of extra weight in her vest for 20 jumps, then goes another 50 to 60 jumps with no weight. She does this three times a week.
"I was never really one for exercise," she said, "but I stayed with it because of the study. And it has made a difference. I've noticed that it has become easy to get out of a chair. And when I go on trips, I walk a lot more; I have the stamina.
"Another big plus," she added, "has been an improvement in my balance. Now when I stumble, I'm able to catch myself without falling."
Another added bonus, Snow said, is that some women in the study who had suffered from arthritis pain reported a decrease in symptoms due to better joint stability.
Snow said more research needs to be done in the field and she is hoping to conduct a larger, multi-center clinical trial of her study to create a model for the prevention of falls and fractures.
The OSU exercise program is being shared with the public through an outreach initiative involving the College of Health and Human Performance and the OSU Extension Service. In addition to offering a series of classes, university researchers and educators have offered instructor training workshops throughout the state.
For more information on the outreach, call 541-737-2713.
The study, initiated by former OSU doctoral student Janet Shaw, was funded by the American Association for Retired Persons Andrus Foundation, the Bone Research Laboratory Clinical Program, and a doctoral dissertation grant from the American Association for University Women.
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Christine Snow, 541-737-6788