In April 2015, Apple launched ResearchKit, an open-source framework to help researchers collect data collection. The framework included MyHeart Counts, a cardiovascular health study administered via a smartphone-based app.

New research shows that the app was successful at tracking participants’ physical activity and that mobile-based studies could be feasible.

Lead researcher Michael V. McConnell, MD, of Stanford University, and colleagues published their results online Dec. 14 in JAMA Cardiology.

“Traditional research on physical activity and cardiovascular health has been based on people writing down what they remembered doing,” McConnell said in a news release. “Mobile devices let us measure more directly people’s activity patterns throughout the day.”

Stanford made the MyHeart Counts app available for free in March 2015. The app includes direct sensor-based measurements of physical activity and fitness.

For this study, 48,968 adults consented to participate and downloaded the app from March 2015 through October 2015. They were from all 50 states and the District of Columbia and had a median age of 36 years old. In addition, 82.2 percent of the participants were male.

The researchers found that clusters of activity levels were significantly correlated with self-reported cardiovascular health. Participants who had the least activity had an elevated risk for chest pain, type 2 diabetes, heart disease and joint pain. Conversely, participants who were more active during the weekend than during the weekdays and those who went from stationary to active more often had a significantly lower risk for those conditions.

The researchers also evaluated 4,990 of the participants who downloaded the app, filled out health questionnaires and completed a six-minute walk test using the phone’s built-in motion sensors at the end of a week. The median age of those participants was 42 years old.

Participants who completed the 6-minute walk test had a mean of 693 steps and a mean distance walked of 455 minutes. They were active during a mean of 15.1 percent of their total recorded time compared with a mean of 14.5 percent for the full group of participants.

Further, more than 34,000 participants reported their mean sleep time, which was 7.8 hours per night. Females slept 0.3 more hours per night than males. The researchers mentioned that participants who went to bed the earliest in the evening had a higher overall life satisfaction compared with those who stayed awake the latest.

"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," McConnell said.

The study had a few limitations, according to the researchers, including that there was an overrepresentation of young males. They also noted that some people do not carry their smartphones with them all the time, so the results might not include all of their physical activity. The motion trackers could not distinguish the cause of periods of lack of motion, either. In addition, they speculated that most participants were likely more active than usual during the first weeks of the study. In future studies, they plan on tracking individuals for multiple weeks.

“To realize the promise of this novel approach to population health research, participant engagement needs to be optimized to maximize full participation of those who have expressed at least enough interest to download the app and consent to join the study,” the researchers wrote.