If you think you're too old to reap any benefits from starting an exercise program, think again. A new study finds that women aged 65 and older who were previously physically active or who became physically active during the study had lower mortality rates than women who remained sedentary. The results are published in the Journal of the American Medical Association.

Studying changes in physical activity

Investigators from four research centers around the country studied more than 9,000 white women aged 65 and older who lived in the community (i.e., were not living in nursing homes or other institutions). Using questionnaires, they assessed each woman's level of walking and other physical activities at the study's start and again about six years later.

The women were followed for up to 12½ years to determine how many had died during the study. The researchers wanted to see whether exercise or changes in exercise pattern were associated with the risk of death from heart disease, cancer, or all causes together. They adjusted their analyses for other factors that could influence the mortality risk, including age, smoking, body mass index (BMI), and the presence of illnesses, such as stroke, diabetes, and osteoporosis.

Never too late to get moving

Not surprisingly, they found that women who were always physically active were at a lower risk for dying compared with those who were sedentary. But, perhaps even more remarkable, was the finding that women who were previously sedentary but who became active during the study were also at a significantly lower risk for dying, compared with those who continued to be sedentary.

How exercise influences mortality

The results of this study don't explain exactly why the mortality rate among women who became active was lower. The researchers offer several possible explanations. It could be because their exercise habits lowered their risk of cardiovascular disease, improved their overall cardio-respiratory fitness, and/or lowered their risk of falls, fractures, and concomitant disability.

It's important to note that this study included only white women, so the results are not necessarily applicable to women of other races. In addition, the researchers relied on the participants' own reports of their physical activity levels, which may have been less reliable than if they studied their activity levels in a more controlled environment.

Taking the first step

Nevertheless, these results add to existing evidence that old and young alike can benefit from adding regular physical activity to their lives. If you've been inactive for a while and would like to start a walking or another exercise program, see your doctor first to get the go-ahead and for advice on how to exercise properly to avoid injury. Taking that first step may just add years to your life.