Exercising more and at a higher intensity could dramatically lower the risk of death in older women, a new study shows.

The study, published Monday in Circulation, is one of the first to investigate physical activity — measured using a wearable device called a triaxial accelerometer — and a clinical outcome. The device measures activity up and down, front to back and side to side, allowing for more precise exercise measurements.

“We used devices to better measure not only higher-intensity physical activities, but also lower-intensity activities and sedentary behavior, which has become of great interest in the last few years,” the study’s lead author I-Min Lee, Sc.D., said in a news release.

Researchers found that more moderate- to vigorous-intensity exercise, such as brisk walking, was associated with a 60 percent to 70 percent lower risk of death at the end of the four-year study among the most active women compared to the least active.

The roughly 17,000 women participating in the study were 72 years old on average. Researchers chose this population for a specific reason.

“Younger people in their 20s and 30s generally can participate in vigorous intensity activities, such as running or playing basketball,” said Lee, a professor of medicine and epidemiology at Harvard University’s medical and public health schools in Boston.

“But for older people, vigorous intensity activity may be impossible, and moderate intensity activity may not even be achievable. So, we were interested in studying potential health benefits associated with light intensity activities that most older people can do,” she said.

Doing more light-intensity activity, such as housework and window shopping in a mall, or more sedentary behavior did not appear to impact the risk of death. However, the finding does not mean light activity isn’t beneficial for other health outcomes not looked at in the study, the researchers stressed.

“We hope to continue this study in the future to examine other health outcomes, and particularly to investigate the details of how much and what kinds of activity are healthful. What is irrefutable is the fact that physical activity is good for your health,” Lee said.

If you have questions or comments about this story, please email