– You will soon be able to participate in cutting-edge medical research from the comfort of your iPhone.

At a hotly anticipated event focused on its new smartwatch earlier this month, Apple surprised attendees by unveiling ResearchKit, a new software platform that taps the power of the iPhone for medical research. Researchers can design apps that use the iPhone's accelerometer, microphone, gyroscope and GPS to gather information about a subject's health, and you can start contributing to science by simply downloading the apps.

It remains to be seen whether ResearchKit will revolutionize medical research: Some are concerned about the reliability of information that users self-report on their iPhones, and others note that people who own pricey Apple gadgets don't exactly mirror the rest of the population. And while Apple stresses that the data will be secure, users may still need to think twice before sharing sensitive medical information with an app in an age of incessant breaches.

Nevertheless, with iPhones flying off the shelves, ResearchKit opens up a new frontier for medical researchers, who have long struggled to find enough participants for their studies and keep them on board. MyHeart Counts — an app developed at the Stanford University School of Medicine that evaluates how patients' activity levels influence cardiovascular health — had been downloaded 52,900 times in the United States and Canada as of Friday morning, just four days after its release, according to the university. More than 22,000 users who downloaded the app consented to the study.

Stanford cardiologist Mike McConnell, the principal investigator on the MyHeart Counts, said such reach is critical for a study on cardiovascular health.

"Cardiologists have a little bit of an odd perspective on all this because we know heart disease and stroke is still the No. 1 killer," he said. "We tend to think of everybody we see as our prevention patient."

After downloading MyHeart Counts and reviewing the consent information, participants are asked to carry their phones with them as much as possible to track their activity, in addition to taking a six-minute walking test. Over the next few months, researchers plan to expand the study to measure how effectively different techniques encourage people to become more active, McConnell said. The app works with the iPhone 5s, 6 and 6 Plus.

Participants are not compensated for their time, but Stanford tries to repay them with information about their heart health, McConnell said. The app gives participants a score that measures their risk for heart disease or a stroke, which they can compare to the ideal score for their age range.

"If you're asking people to donate data, we certainly want to give feedback on how they're doing relative to the different guidelines," McConnell said.

MyHeart Counts was part of an initial batch of five apps that Apple released last week, after announcing ResearchKit. The other apps study asthma, breast cancer, diabetes and Parkinson's disease. Apple says an open source framework will debut next month.