Exercise levels predict lifespan better than smoking, medical history

Wearable activity trackers may pave the way for a better method to predict short term death risk, suggests a new study, which found that exercise data was more accurate than other risk factors, such as smoking and medical history.

Being able to make an accurate prediction about a person's risk of death can help them prolong their lives. Usually, doctors base these estimates on lifestyle choices, such as smoking and alcohol consumption, and health factors, such as cancer or heart disease history.

But new findings published in The Journal of Gerontology: 

Researchers at John Hopkins Medicine in Baltimore, MD, studied the association between physical activity and risk of death.

"We've been interested in studying physical activity and how accumulating it in spurts throughout the day could predict mortality because activity is a factor that can be changed, unlike age or genetics," says professor Ciprian Crainiceanu, Ph.D., from the Johns Hopkins Bloomberg School of Public Health.

Their work is not the first to find such a link, but, according to the team, the results might be some of the first to offer concrete proof that wearable technology works better for predicting a person's risk of mortality than other means.
Using technology to measure exercise

The study's data set came from the National Health and Nutrition Examination Survey (NHANES) carried out in 2003–2004 and 2005–2006.

• Involving almost 3,000 U.S. adults between the ages of 50 and 84, it examined more than 30 predictors of 5-year all-cause mortality, using survey responses, medical records, and laboratory test results.
• Physical activity made up 20 of these predictors, including total activity, time spent doing moderate to vigorous activity, and time spent not moving at all.
• To measure such activity, participants — 51% of whom were men — were asked to wear a wearable activity tracker on their hip for 7 days in a row. They were told only to remove the device when showering, swimming, or sleeping.
• The research team was able to use the data to categorize which factors best predicted death risk within the next 5 years. However, they were unable to tell when people were sleeping or whether they had removed the tracker for other reasons.
• Physical activity's link to lifespan
• Wearable trackers predicted the risk of death more accurately than surveys and other methods that doctors commonly use.
• "The most surprising finding," says lead author Ekaterina Smirnova, M.S., Ph.D., "was that a simple summary of measures of activity derived from a hip-worn accelerometer over a week outperformed well-established mortality risk factors, such as age, cancer, diabetes, and smoking."

Smirnova is an assistant professor of biostatistics at Virginia Commonwealth University, VA.

The wearable trackers designated death risk 30% better than smoking-related information did, and was 40% more accurate than using data involving stroke or cancer history.


The researchers found that total daily physical activity was the strongest mortality predictor. Age came second, followed by time spent performing moderate to vigorous physical exercise.

Specifically, examining the amount of physical activity that a person performed between noon and 2 p.m. proved to be a better indicator of death risk than more established risk factors, such as alcohol consumption and diabetes.
No guarantees just yet

Andrew Leroux, co-author and Ph.D. candidate at John Hopkins, says the study confirms "a link between physical activity and short term mortality risk in an older population."

But, he adds, "the data [do not] guarantee that one's risk of mortality is going to be lower with more physical activity."

This does not take away from the fact that wearable tracker measurements, rather than self-reported data, may help doctors "intervene" more appropriately and therefore improve patient health.

Assistant professor of medicine at the John Hopkins University School of Medicine, Jacek Urbanek, Ph.D., notes that "the technology is readily available and relatively inexpensive, so it seems feasible to be able to incorporate recommendations for its use into a physician's practice."

But it does mean that further study is necessary. Researchers are hoping to use their findings in clinical trials designed to strengthen the link between physical activity and lifespan.