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My Heart Counts Cardiovascular Health Study: Next Gen

My Heart Counts Cardiovascular Health Study

Status
Not yet recruiting
Phases
Unknown
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT07428122
Acronym
MHC
Enrollment
15000
Registered
2026-02-23
Start date
2026-04-30
Completion date
2035-12-31
Last updated
2026-02-23

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Cardiovascular Health, Physical Activity

Keywords

physical activity, fitness, heart health, mobile health, digital health, cardiovascular risk, behavioral interventions

Brief summary

The My Heart Counts Cardiovascular Health Study will utilize mobile health capabilities of smartphones to assess daily activity measures and compare these to measures of cardiovascular health risk factors and fitness. The study aims to collect cardiovascular health data on a diverse population by making the application available on both iOS and Android platforms. Using smartphone sensors and connected devices, the study will collect physical activity metrics, heart rate data, and responses to health questionnaires. The study includes a randomized crossover trial component examining the effectiveness of personalized activity coaching prompts generated by a language model compared to generic prompts.

Detailed description

My Heart Counts is a smartphone-based mobile cardiovascular health research study designed to collect data on physical activity and heart health across a broad population. This new version expands on the original study (IRB-31409) with several key improvements: inclusion of Android users alongside iOS, creation of a Spanish-language version, and, for future versions of the app, development of a platform architecture that can host multiple sub-studies. The study will utilize smartphone sensors and connected devices to measure physical activity patterns, fitness levels through standardized tests (6-minute walk test, 12-minute run/walk test), and cardiovascular risk factors reported through health questionnaires. All data collection occurs remotely through participants' smartphones without requiring clinical visits. A key component of the study is a 14-day randomized crossover trial evaluating the effectiveness of different physical activity coaching approaches. Participants will experience both personalized coaching messages generated by a large language model and standard activity prompts, each for 7 days, in a randomly assigned order. The primary outcome will be the change in physical activity levels between intervention periods. The study will serve as a digital biobank, with data made available to qualified researchers after appropriate de-identification. This platform approach will enable efficient recruitment for future cardiovascular health sub-studies without requiring development of new applications.

Interventions

BEHAVIORALPersonalized LLM Coaching

Participants receive daily text messages containing exercise coaching prompts generated by a large language model (LLM) that are personalized to the user's demographic information for a period of 7 days.

BEHAVIORALGeneric Activity Prompts

Participants receive generic daily activity prompts for a period of 7 days (e.g., "Push yourself! Reach 10,000 steps today.")

Sponsors

Stanford University
Lead SponsorOTHER
Imperial College London
CollaboratorOTHER
University of Washington
CollaboratorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
PREVENTION
Masking
NONE

Eligibility

Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes

Inclusion criteria

* 18 years of age or older * Resident of the United States * Able to read, understand and consent to study

Exclusion criteria

• Not owning a compatible iOS or Android smartphone

Design outcomes

Primary

MeasureTime frameDescription
Change in Physical Activity levelsTime Frame: 14 days (7 days in each intervention period)Change in daily physical activity levels as measured by step count smartphone sensors and connected health devices.

Contacts

CONTACTAnders Johnson
acjohn@stanford.edu8016984141
CONTACTDaniel Seung Kim,, MD, PhD, MPH
myheartcounts@stanford.edu(206) 465-5858

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Feb 24, 2026