Understanding physical activity in the elderly

Use of accelerometer and questionnaire for accurate information

"We all know it is good for people to be active. The question is, what amount of activity is really necessary for older people to maintain their health and mobility? With this study, we hope to find out," said LaCroix, a co-investigator of the Women’s Health Initiative. The WHI Clinical Coordinating Center is housed at the Hutchinson Center.

The WHI is a rich information resource when it comes to octogenarian health. "We now have more than 30,000 women enrolled in WHI who are over 80," LaCroix said. "We couldn’t do this kind of research without them. Lots of these women are still very active. It’s no longer the case that you’re ‘old’ when you get to be 80. Eighty is the new 60."

This $5.2 million study, funded by the National Heart, Lung and Blood Institute, will involve researchers at seven WHI study sites nationwide. It is the first study of its kind among very elderly women to objectively measure physical activity without solely relying on self-reporting via questionnaires, LaCroix said.

Questionnaires about physical activity don’t provide a completely accurate picture for two reasons.  "First, most people overestimate their activity and underestimate their sedentary time. Most people tend to live very sedentary lifestyles and would be shocked if they actually knew how little they really moved each day," she said. "Second, questionnaires used to measure physical activity don’t capture a lot of the things that older people do. They don’t ask about folding the laundry or playing with the grandchildren, and so those things don’t get measured."

This new study should provide more accurate data because, in addition to using the accelerometer to get an objective picture of everyday activity, LaCroix will use an expanded questionnaire that will include realistic examples of the types of activities that seniors actually do, she said.

It is estimated that 40 percent of older Americans meet physical-activity guidelines according to their self-reported activity. However, only 2.4 percent actually meet these guidelines based on objective accelerometer data, LaCroix said.

Understanding link between activity and disease risk

This endeavor is particularly relevant because the "oldest old" have been neglected when it comes to assessing the role of physical activity in healthy aging. There's also little known about how sedentary behavior affects a variety of diseases in the elderly, including cancer, heart disease and dementia. The importance of this study is underscored further by the expanding population of older women in the U.S. and worldwide. Baby boomers will start turning 80 in 2026, and by 2040, nearly 10 percent of the U.S. female population will be octogenarians. "Women who survive to age 85 have a life expectancy of 7.2 years," LaCroix said, "so getting information relevant to this age group is really important."

To conduct the study, during the next four years, trained WHI personnel will make 8,000 home visits in 40 metropolitan areas nationwide, starting in Seattle, Houston, San Antonio, Phoenix and Tucson. During these visits, the study participants will be given an accelerometer to wear for a week at all times (except while bathing) as they go about their normal activities. The women also will be asked to perform a series of baseline physical-performance tests and fill out a physical-activity questionnaire and keep a record of falls. Two hundred of the women also will undergo treadmill testing at two of the study sites to establish thresholds of light, moderate and vigorous activity.

"Establishing definitions of light, moderate and vigorous activity for this older age group has not been done before," LaCroix said. "Riding your bike for 30 miles when you’re 18 might be a vigorous activity, but when you’re 80 it might be walking for three blocks."

The focus of this study is the impact of physical activity on heart disease and risk of falling. Ultimately, the data will be used to support future research on how much total physical activity is needed to reduce the risk of a variety of diseases, including breast and colon cancer, type 2 diabetes and dementia/Alzheimer disease, as well as physical disability.

"Ultimately we want to connect the dots between how physical activity and sedentary lifestyle impact these endpoints among the very elderly," LaCroix said. "A lot of older adults—probably the vast majority—don’t do the kinds of exercises classified as vigorous for middle-aged people. We ultimately want to be able to advise people on the value of everyday kinds of activity and how much is needed to prevent disease. We’ll be interested in light and total physical activity—incremental activity," LaCroix said.

The American Cancer Society physical activity guidelines for cancer prevention, for example, call for at least 150 minutes per week of moderate-intensity activity or 75 minutes per week of vigorous exercise—a recommendation that aligns with federal government recommendations as well. The ACS also recommends limiting time spent sitting, as excessive sitting is associated with an increased risk of obesity, heart disease, diabetes and various types of cancer.

Stanford University, University of Alabama-Birmingham, University of North Carolina at Chapel Hill, Brigham and Women’s Hospital at Harvard University, the University of Illinois and the State University of New York-Buffalo are collaborating sites on the study.