Cardiovascular HealthMHCNCT07428122
My Heart Counts Cardiovascular Health Study: Next Gen
A study testing Personalized LLM Coaching and Generic Activity Prompts in people with Cardiovascular Health and Physical Activity, run by Stanford University.
Trial 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. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Cardiovascular Health, Physical Activity
- What is being tested?
- Personalized LLM Coaching and Generic Activity Prompts
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 15,000 participants
- Where
- No sites listed yet
- Study dates
- 30 Apr 2026to 31 Dec 2035
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- 18 years of age or older
- Resident of the United States
- Able to read, understand and consent to study
Who cannot join
- Not owning a compatible iOS or Android smartphone
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: My Heart Counts Cardiovascular Health Study
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.
Read the 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.
- Conditions
- Cardiovascular Health, Physical Activity
- Being tested
- Personalized LLM Coaching, Generic Activity Prompts
- Keywords
- physical activity, fitness, heart health, mobile health, digital health, cardiovascular risk, behavioral interventions
- Medical subject headings
- Motor Activity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Personalized LLM CoachingBehavioural
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.
Generic Activity PromptsBehavioural
Participants receive generic daily activity prompts for a period of 7 days (e.g., "Push yourself! Reach 10,000 steps today.")
| Study group | Role | What they receive |
|---|---|---|
| Personalized LLM Coaching | Active comparator | Not described Receives: Behavioral: Personalized LLM Coaching |
| Generic Activity Prompts | Placebo comparator | Not described Receives: Behavioral: Generic Activity Prompts |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Physical Activity levels
Change in daily physical activity levels as measured by step count smartphone sensors and connected health devices.
Measured: Time Frame: 14 days (7 days in each intervention period)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted23 Feb 2026
- Study start30 Apr 2026 (estimated)
- Primary completion31 Dec 2035 (estimated)
- Study completion31 Dec 2035 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Cardiovascular HealthStudies of the same condition, open and under way.
- More trials run by Stanford UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Enrolment
- 15,000 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Stanford University
- Sponsor type
- University, hospital or other
- Collaborators
- Imperial College London, University of Washington
- Responsible party
- Principal investigator, Euan Ashley, Stanford University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07428122
- Sponsor's protocol ID
- 78735
- Acronym
- MHC
- Status last verified
- Feb 2026
- First submitted
- 13 Jun 2025
- Last updated
- 23 Feb 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 23 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- My Heart Counts Cardiovascular Health Study
- ClinicalTrials.gov ID
- NCT07428122
- Acronym / sponsor ID
- MHC / 78735
- Conditions
- Cardiovascular Health, Physical Activity
- Keywords
- physical activity, fitness, heart health, mobile health, digital health, cardiovascular risk, behavioral interventions
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 15,000 participants (estimated)
- Lead sponsor
- Stanford UniversityUniversity, hospital or other
- Collaborators
- Imperial College London, University of Washington
- Study start
- 30 Apr 2026 (estimated)
- Primary completion
- 31 Dec 2035 (estimated)
- Study completion
- 31 Dec 2035 (estimated)
- First posted
- 23 Feb 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Personalized LLM Coaching | Active comparator | Behavioral: Personalized LLM Coaching |
| Generic Activity Prompts | Placebo comparator | Behavioral: Generic Activity Prompts |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- 18 years of age or older
- Resident of the United States
- Able to read, understand and consent to study
Key exclusion criteria (1 listed)
- Not owning a compatible iOS or Android smartphone
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Personalized LLM CoachingParticipants 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. | Behavioural | Personalized LLM Coaching |
| Generic Activity PromptsParticipants receive generic daily activity prompts for a period of 7 days (e.g., "Push yourself! Reach 10,000 steps today.") | Behavioural | Generic Activity Prompts |
Primary outcome
Change in Physical Activity levels
Time frame: Time 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.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 23 Feb 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Questions about this trial
What is this clinical trial studying?
A study testing Personalized LLM Coaching and Generic Activity Prompts in people with Cardiovascular Health and Physical Activity, run by Stanford University.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 23 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Anders Johnson (8016984141, acjohn@stanford.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Physical Activity levels (time frame: Time Frame: 14 days (7 days in each intervention period)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 23 Feb 2026; AzTrials last refreshed its copy on 6 Nov 2026.