New study shows physical activity is top predictor of when you might die

If you need one more reason to follow through on your New Year's resolution to get more exercise next year, consider this headline from a recent study in the journal Medicine & Science in Sports & Exercise: "Objective Physical Activity is the Strongest Predictor of All-Cause Mortality."

Translated into layman's terms, the best way to predict how soon you'll die is how much physical activity you do. Move, or maybe die, in other words.

That's the conclusion of work conducted by researchers from the University of Colorado and Johns Hopkins University, along with a young biostatistician from the University of Minnesota named Erjia Cui.

Cui and his colleagues crunched a bunch of data extracted from a large ongoing survey run by the Centers for Disease Control that involved 3,653 Americans ages 50 to 80 who were asked to wear a research-grade wrist accelerometer for a week.

The devices are similar to a Fitbit or other commercial fitness tracker, only more accurate. The physical activity data was gathered between 2011 and 2014. Then the researchers compared the results of the test subjects who were still living in 2019 and the 416 test subjects who had died by that time.

The surprising result: The level of physical activity measured by the wearable devices is a better predictor of whether you're going to die soon than whether you're obese, have diabetes or smoke or have heart disease.

Objectively measured physical activity beats your own opinion of your physical health on telling whether the end is near. It's even a bit better than age as a predictor of your impending doom.

"We know age is a strong predictor, but here we show that physical activity measures are an even better, stronger predictor," said Cui, an assistant professor at the U School of Public Health. "This makes them one of the strongest predictors of all-cause mortality."

The study found that the amount of physical activity you get in your 10 most active hours is especially good at predicting mortality risk, indicating periods of higher intensity activity is associated with lower risk of dying.

"Those individuals who are very active in the 10 most active hours will have a lower risk than those with a consistently moderate physical activity throughout the entire day," Cui said.

The study only shows the association between physical activity and lower death risk, not the causation. Maybe it isn't physical activity that makes people live longer. Maybe it's bad health that makes some people less active.

But with the wealth of other research showing the health benefits of exercise, it's hard not to conclude we should keep moving.

"Physical activity is a modifiable risk factor, which means we can encourage ourselves to do more exercise," Cui said.

Cui said he's continuing research on wearable devices and physical activity, including a study that will measure whether "gamification" of physical activity involving competing groups of people wearing fitness devices will result in better outcomes.

Cui himself wears an Apple Watch, but he said almost all of us carry around a smart phone that can be set up to track our physical activity.

"The important message is, try to do more exercise, especially during the daytime. That's good for you," Cui said. "If you have a wearable device, look at the numbers. Our study tells you that these numbers actually matter."