Further Information


MyHeart Counts discussion 

Despite compelling evidence for physical activity, 80% of American adults do not currently meet the weekly exercise recommendations. Not surprisingly, cardiovascular disease is the leading cause of morbidity and mortality worldwide; sadly, this is preventable. 

My Heart Counts (MHC) is one of the original ResearchKit studies with the goal of developing an extensive source of data which will inform future cardiovascular health guidelines while providing participants with information about their heart risk, fitness (through a 6-minute walk test) and a crossover trial to promote physical activity.

In many ways it was a large success with over 60,000 iPhone owners having joined MyHeart Counts since inception in 2015.   Researchers have also benefited; a 6-month data portal has been accessed 25 times to date to study a variety of topics ranging from describing “a normal distribution of physical activity and hours of sleep among participants of the MyHeartCounts study, stratified by demographic information” to studying the "usage and user attrition in mobile apps" to evaluating “the impacts of air pollution and climatic factors on participant's sleep quality, physical activity, and heart health" . Data gathered and analyzed for MyHeart Counts concluded that smartphone-based physical activity coaching interventions could significantly increase daily physical activity of users.

In other ways, MHC has room for improvement:

  1. It was released only on iOS, creating a population bias due to not being on Android

  2. The intervention to promote physical activity only had a modest effect

  3. The fitness measurement active task in the form of a 6 minute walk test is only a submaximal test, not necessarily informative for the bulk of MHC users who need a maximal test

  4. Heart risk calculations have limited population applicability


Rationale for a implementation of a biodesign study: My Fitness Counts

We are interested in addressing each of these concerns; however each present challenges that can be alleviated with an intermediate biodesign study before releasing a new My Heart Counts.  

To bring the MHC onto iOS and Android simultaneously, we are leveraging a platform called MyStudies.  Moving to a new platform represents a large task; testing that study apps are optimal from user experience and technical accuracy perspectives is something we want to prove out before conducting our next randomized controlled trial. 

Since physically active individuals are at lower risk for many conditions, including cardiovascular disease, metabolic syndrome, and depression, it stands to reason the use of smartphones and wearable devices could be harnessed to help motivate an increase in physical activity to ultimately achieve better health. 

There is increasing evidence to suggest a relationship between daily step count and health outcomes. In MyHeart Counts 2.0, we tested the hypothesis that light-touch interventions, delivered entirely 'digitally' via a smart-device, can increase one's step count using a crossover design implementing four one-week interventions.  Our results showed a modest, but significant, increase during the interventions of activity as measured by step count or % time detective in an active state such as walking or running. In years since MyHeart Counts 2.0, consumers have found an interest in fitness programs such as Peloton, Nike Running Club, and Apple Fitness +. At the same time, researchers have made powerful new tools to measure fitness, such as the cardiorespiratory fitness modules from the All of Us Study. The primary objective of this study is to implement and validate cardiorespiratory fitness tests on a digital platform in order to design a randomized controlled clinical trial with the ultimate goal of improving physical fitness in a subjective, measurable way. In doing so, we will model the effectiveness of such programs on a new cross platform that future researchers will be able to build upon. 

The secondary objective of this study is to collect participant self-reported data by way of surveys to calibrate a widely applicable cardiovascular risk score. Previous versions of the MyHeart Counts app used the ASCVD (atherosclerotic cardiovascular disease) risk score for participant feedback. This well established cardiovascular risk score provides the 10-year risk of heart disease and stroke in patients, and is endorsed by the American Heart Association, the American College of Cardiologists, and is most frequently used by cardiologists in the United States.  The limitations of this risk score include age range (only applicable to ages 40-79), sample population (primarily white american, african american), population size (thousands sampled in a country of 330 million), and is thought to underestimate the 10-year risk for some race/ethnic groups, including American Indians, some Asian Americans (e.g., of south Asian ancestry), and some Hispanics (e.g., Puerto Ricans). An alternative risk score utilized in the United Kingdom is called the QRisk 3. This score is based on a larger breadth of risk factors not currently used in the ASCVD including but not limited to rheumatological disease, medications, diabetes and hypertension status.

Because the primary use of these risk estimates is to facilitate the very important discussion regarding risk reduction through lifestyle change, the imprecision introduced is small enough to justify proceeding with lifestyle change counseling informed by these results.

Detailed Description of the Technology 

The previous MyHeart Counts study has been hugely successful, however, it has limitations with regards to operating under a HIPAA carve-out, amassed technical debt since launch and an iOS-dependence that limits unbiased recruitment.  Thus we are proposing the launch of a new cross platform version powered by FDA MyStudies running on Google Cloud Platform (will be referred to “MyStudies” hereafter). 



MyStudies is an open-source platform to author and conduct digital health studies on iOS and Android that was sponsored by the FDA Sentinel Initiative as part of an award that went to Harvard Pilgrim Health Care and was implemented by Boston Technology Corporation. Google Cloud Platform (GCP) has engaged Boston Technology Corporation to modify the original architecture, constrained by dependence on a Labkey server, to run on GCP. Together, GCP, BTC and Stanford University are extending MyStudies functionality to support what is required for the new My Heart Counts.


Smartphone-based Cardiorespiratory Fitness Testing:

One discipline of clinical measurement of interest to us is exercise testing, specifically the measure of cardiorespiratory fitness (CRF).  Traditionally this is measured by VO2max, defined as the maximum rate of oxygen consumption, distribution, and utilization by the body during periods of high intensity exercise where V is the volume of oxygen as a measure of a unit of time. VO2max is a measure of function of pulmonary and cardiovascular systems, systemic circulation, peripheral circulation, blood, neuromuscular units, and muscle metabolism.

VO2max can be proxied by measuring heart rate recovery or distance walked/ran, depending on fitness level and activity limitations.  Previous versions of MyHeart Counts included a 6 minute walk test (6-MWT) only, a test that involves measuring the distance one can walk within 6 minutes.  It is most suitable for participants with limited daily fitness, such as advanced heart or lung disease, but less useful for the general population as the test results will provide submaximal VO2max.  For this biodesign study, we aim to leverage sensory data collected while participants are actively using their smartphones (termed “Active Task(s)” by Apple ReasearchKit) to employ two additional protocols for estimating VO2max. The first is the Cooper Protocol, which consists of a 12-minute run/walk test (12-MRT) where the participant is asked to cover as much distance as possible during 12 minutes on a flat surface. The second test is the Tecumseh protocol, which consists of a 3-minute submaximal step test (3-MST) where individuals step up and down an 8-inch step at a constant rate for 3 minutes. These two tests will be in addition to the baseline 6-MWT. 

The Cooper Protocol and the Tecumseh Protocol as described above were initially defined by the All of Us study, however only the Tecumseh Protocol was tested and validated using sensory data collection on both IOS and Android (renamed “Heart Snapshot”), with open source code available. A sub-aim of this study will to validate the use of both tests for future clinical trials from . Both protocols use heart rate recovery, that can be measured by a camera-based Active Task or from a participant supplied activity monitor. 

Participants will be offered the opportunity to complete the baseline 6-MWT as well as the 12-MRT and/or the 3-MST depending on their comfort and physical activity level. Physical activity level will be determined using the Physical Activity Readiness Questionnaire (2021 PAR-Q+*). This widely-accepted tool is used to assess an individual’s fitness for tests involving cardiovascular exercise.  

Participants will be able to choose which physical activity assessments they want to complete.   For this study, consistency will be the key in order to track changes highlighted in aims - participants will be asked to retake the same test, regardless of test, at every checkpoint.