WEDNESDAY, Dec. 14, 2016 (HealthDay News) -- Smartphones might revolutionize cardiac research by giving instant, accurate insight into the physical activity of people using them, a new study finds.

"People check these devices [an average of] 46 times a day," noted study senior author Dr. Euan Ashley, an associate professor of cardiovascular medicine at Stanford University in Palo Alto, Calif.

"From a cardiovascular health standpoint, we can use that personal attachment to measure physical activity, heart rate and more," he said in a university news release.

In the study, Ashley's team enlisted subjects via a free iPhone app called MyHeart Counts.

The researchers enrolled more than 47,000 Americans across all 50 states, and were able to track data about the physical activity of nearly 5,000 participants who took a six-minute walking fitness test.

"The ultimate goals of the MyHeart Counts study are to provide real-world evidence of both the physical activity patterns most beneficial to people and the most effective behavioral motivation approaches to promote healthy activity," said study co-lead author Dr. Michael McConnell. He's a professor of cardiovascular medicine at Stanford.

Why is it beneficial to get numbers from a smartphone? Because people often overestimate how much they exercise when they are simply asked in a survey, the researchers said.

"Traditional research on physical activity and cardiovascular health has been based on people writing down what they remembered doing," McConnell said. "Mobile devices let us measure more directly people's activity patterns throughout the day."

The researchers found that people who were active throughout the day, and not just once for a fairly short session, were healthier on the cardiac front. And those who mostly exercised on the weekend and went to bed early tended to be healthier.

One heart specialist who reviewed the new study believes the smartphone initiative has merit.

"It helps health care providers and patients alike in monitoring physical activity, setting goals, and achieving desired results," said Dr. Satjit Bhusri, a cardiologist at Lenox Hill Hospital in New York City. "As a result, we have up-to-date information on our patients' progress and prevention of heart disease."

Dr. Stacey Rosen is vice president of Northwell Health's Katz Institute for Women's Health in New Hyde Park, N.Y. She believes that tracking people via a smartphone could greatly expand research opportunities.

Right now, she said, "there are challenges to large-scale research initiatives -- cost, staffing and recruitment and retention of subjects."

"Enhancing the ability of the almost ubiquitous smartphone, to help us better understand ways to modify behavior that impact positively on heart disease risk, is a major game-changer," Rosen said.

The study was published Dec. 14 in JAMA Cardiology.

More information

There's more on keeping your heart healthy at the American Heart Association.