Just like our muscles, our bones are living tissue that we can strengthen through exercise. Peak bone mass, a measure of how dense and strong bones are, is usually the highest when we’re in our twenties; after that, we begin to slowly lose bone.
After age 50, about one-half of all women will have a fracture of the hip, wrist, or spine at some point during their lifetime, according to the National Institute of Health.
But maybe there’s a way to prevent some of those fractures.
A large new study of women ages 50 to 79 years old published October 25, 2019, in JAMA Network Open suggested that women who spend more time being active — even if the exercise is light to moderate or just walking — can reduce their risk of hip fracture compared with less active women. Investigators found that even light activity, like doing laundry or slow dancing, was associated with fewer fractures.
This study provides new insights into how physical activity can impact fracture risk, says Kurt A. Kennel, MD, an endocrinologist at the Mayo Clinic in Rochester, Minnesota, who was not involved in the research.
“In addition to having very robust analysis of the light exercise group, researchers were able to capture quantity of activity as well as what type of activity,” says Dr. Kennel. “These results show that long-term active lifestyles make a meaningful difference in fracture risk over long periods of time.”
Household Chores and Light Exercise Reduce Hip Fracture Risk
To find out if the intensity and amount of exercise make a difference in preventing fracture, researchers followed 77,206 postmenopausal women for an average of 14 years. The women were all part of the continuing Women’s Health Initiative Study, a long-term national health study that provides that data for research about heart disease, breast and colon cancer, and osteoporosis fractures in postmenopausal women.
Physical activity was tracked by questionnaires that the women answered, which asked how much and how long they engaged in activities that were classified as mild, moderate, or strenuous physical activity (PA).
Strenuous PA was activity that resulted in sweating and a fast heartbeat and included aerobics, aerobic dancing, jogging, tennis, or swimming laps.
Moderate PA was defined as less exhausting; biking outdoors, using an exercise machine like an elliptical, calisthenics, easy swimming, and popular or folk dancing were all considered moderate PA.
Mild PA included things like slow dancing, bowling, or golf.
Women also answered questions about how much they walked for more than 10 minutes at a time, and how fast they walked. Time spent on physically oriented household chores, like scrubbing floors, sweeping, and vacuuming; and yard work, like mowing, raking, and shoveling snow, were also recorded.
The women also reported sedentary time: how much time they spent sitting at work, while eating, riding in a car or bus, as well as how much time they spent sitting or lying down watching television or resting but not sleeping.
Participants were tracked for different types of fracture, including hip, knee, wrist, forearm, or spine. During the follow-up period, 25,516 women, or about 1 in 3, experienced a bone fracture.
After controlling for factors like medical history, diet, smoking, household income, education, and body mass index (BMI), investigators found that women with higher levels of all kinds of physical activity were associated with an 18 percent reduction in risk of hip fracture compared with women with the least activity.
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Focus on ‘Normal’ Activities Sets Study Apart From Previous Research
These findings are unique because although there has been research that shows that exercise has a role in reducing fracture risk, this study was able to follow the risk of fracture prospectively over a long period of time, says Jean Wactawski-Wende, PhD, a distinguished professor in the department of epidemiology and environmental health at the University at Buffalo in New York, and coauthor of the study.
“Typically, studies have looked at vigorous activity, which we were able to do, but we were also able to access and consider light to moderate activity, particularly regular walking,” says Dr. Wactawski-Wende. Regular walking is critically important in the population of older women, many of whom may be reluctant to start vigorous activity, according to Wactawski-Wende. “Walking is an activity that most everyone can do and showed a reduction in total hip fractures. That’s really important,” she says.
Walking, mild activity, moderate-to-vigorous activity, and yard work and household chores were also associated with a lower risk of hip fracture.
“We had an assessment of household chores, which are activities that many women this age do, that we found to also be associated with reduction in fractures,” she says.
Sedentary time greater than 9.5 hours per day — regardless of your other physical activity — was associated increased risk of fracture, adds Wactawski-Wende.
“Although the real risk for fracture for women may come a decade or so later than the average woman in this study, these findings validate the idea that women in their fifties and sixties really should be exercising with a mind toward wellness as they age,” says Kennel. This data shows how important that physical activity is as part of that plan, he adds.
"These results also confirm what we’ve already learned in earlier studies, which is that there’s clearly value in moderate to more intense physical activity,” says Kennel. “As we get older, we tend to fall away from those activities and regress to mostly just light activity,” he says. Moderate to intense activity is important when it comes to reducing the risk of fracture, probably by keeping people fitter as they get older, says Kennel.
Higher Levels of Activity Can Increase the Risk of Knee, Wrist, and Forearm Fracture
All the associations between activity and fracture risk were not positive, however. More total activity was associated with a greater risk of knee fracture, and women who engaged in more moderate to vigorous activity had a higher risk of fracturing their wrist or forearm.
The study authors suggest that women capable of doing moderate to vigorous activity may be more functional and more likely to break a fall with outstretched hands.
“I think it’s a valid point that people who are more active may be engaged in activities that may result in falls and they may respond to those falls as most of us do — by putting our hands out and breaking our wrists,” says Kennel. “People do different things at different ages that put them at risk of breaking bones,” he adds.
Even though some activity increased risk for knee or wrist fracture, it’s reassuring and important to note that all forms of exercise and intensities of activity were beneficial in preventing the more serious fractures of aging, like hip fractures, because those are the fractures that are more debilitating, says Kennel. “It’s not fun to break your wrist, but the real value of osteoporosis management is trying to prevent those fractures that result in physical function and loss of independence, such as a hip fracture,” he says.
The study controlled for other things in people’s lives that would make it less likely for them to break bones that are also associated with high levels of physical activity, such as better nutrition and less smoking — things that in and of themselves might make people’s bones healthier and less likely to break, says Kennel. “Even when they controlled for these variables, across all those different types of groups, physical activity still seemed to make a difference, which suggests it must be providing some benefit beyond being part of a healthy lifestyle,” he says.
One possible factor that could account for the reduced risk is that falling is a big part of fractures, says Kennel. “If you have two people with the same bone density and one is falling and one’s not falling, the person who is falling is more likely to have fractures. It could be that people who are more active also have a balance benefit or a strength benefit, or even an overall higher resistance to becoming frail with aging,” says Kennel.
A limitation of the study is that most of the participants of the Women’s Health Initiative are white (85 percent) and many are highly educated, says Kennel. “The study population is a still a relevant population because this is a group that tends to have osteoporosis and fractures, but in terms of generalizing these findings to other groups or populations there, could be some disparities there,” he says. That can be a limitation of this type of observational study because the people who volunteer don’t always represent a cross section of all different types of people in the American population, adds Kennel.
Tips for Reducing Your Fracture Risk
These results validate the idea that everyone can be active, says Kennel. “Anyone, regardless of their health situation, has some potential to improve their activity level,” he says. That includes people who are starting from a very deconditioned state or haven’t been exercisers traditionally, he adds.
Kennel offers a few tips for being active to help prevent hip fracture:
- Try spending less time being sedentary and walking more, even if it’s just moderate walking.
- If you’re already doing a lot of light to moderate physical activity, try expanding to incorporate some more intense types of activity, such as swimming or resistance training.
- You don’t have to go to the gym to increase the amount or intensity of your exercise. “Improving your fitness can involve simple things like using one’s own body weight, like a chair stand exercise or squatting against the wall. Exercising with resistance bands can also build strength,” says Kennel.
- Explore activities you’ve been traditionally interested in, if possible, because you’re more likely to keep it up. “If you have no direction or inclination at all, try going to the local community center or fitness center and see a wellness coach. It’s helpful to get advice from someone who can work with you from where you’re at and offer suggestions,” says Kennel.
Increasing your activity may not make a big difference in your bone density test, Kennel cautions. “The real benefit from exercise is better fitness and balance, increased strength and avoidance of becoming frail. That may be why exercise makes such a difference in helping prevent fractures,” says Kennel.