Researchers at Stanford University School of Medicine studied the effect rapid, large-scale and real-time measurements of a person's physical activity in relation to cardiovascular research.

In  March 2015, researchers launched a free iPhone app called MyHeart Counts, which gave users the ability to participate a first-of-its-kind cardiovascular research study which has been published in JAMA Cardiology.

The app, which uses Apple's ResearchKit framework, gives users a simple way to consent to participate, measure daily activities, complete tasks and answer surveys through their iPhones. Researchers had enrolled 47,109 participants from all 50 states within six months of the app launching.

In previous studies, researchers had to rely on participants estimating the time they spent on physical activity in the preceding days, with participants consistently overestimating their activity levels.

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," Dr. Michael McConnell, a professor of cardiovascular medicine at Stanford currently serving as head of cardiovascular health innovations at Verily Life Sciences, said in a press release.

The importance of physical activity, fitness, sleep and diet have already been established in maintaining cardiovascular health with low fitness levels being a key risk factor for heart disease. Studies have shown insufficient physical activity accounts for 5.3 million deaths per year worldwide.

Participants were asked to keep their phones with them as much as possible and to provide basic health information such as age, weight, blood pressure, cholesterol levels and risk factors. All of the information was kept confidential.

Results showed participant groups with similar activity levels, those who were active throughout the day versus short intervals of activity, reported better levels of cardiovascular health with lower rates of chest pain, heart attacks and atrial fibrillation.