ExerciseNCT06880315
LLM-Generated Coaching Prompts
A study testing Pre-Generated Personalized LLM Coaching Impact in people with Exercise, run by Stanford University.
Trial summary
This pilot study aims to evaluate whether personalized coaching prompts generated by a large language model (LLM) can effectively increase physical activity levels among participants. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Exercise
- What is being tested?
- Pre-Generated Personalized LLM Coaching Impact
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 50 participants
- Where
- No sites listed yet
- Study dates
- 20 Jan 2027to 1 Dec 2027
- 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
- Age: Participants must be 18 years or older.
- Health Status: Participants must be healthy enough to engage in physical activity.
- Language Proficiency: Participants must be able to read, understand, and consent in English or Spanish (dependent on which is being studied).
- Device Ownership: Participants must possess an iPhone and an Apple Watch.
- Data Sharing: Participants must be willing to share their HealthKit data via secure upload.
Who cannot join
- Age: Participants under the age of 18.
- Health Status: Participants who are not healthy enough to engage in physical activity.
- Language Proficiency: Participants who cannot read, understand, or consent in English or Spanish.
- Device Ownership: Participants who do not have both an iPhone and an Apple Watch.
- Data Sharing: Participants unwilling to share their HealthKit data via secure upload.
About this study
Official title: Enhancing Physical Activity With LLM-Generated Coaching Prompts: A My Heart Counts Study
This pilot study aims to evaluate whether personalized coaching prompts generated by a large language model (LLM) can effectively increase physical activity levels among participants. The study will involve 50 participants who will receive daily text messages, either personalized by the LLM or generic, over a 14-day period. Participants will share their HealthKit data for analysis. The findings will inform the development of future versions of the My Heart Counts application, enhancing user engagement and health outcomes.
- Conditions
- Exercise
- Being tested
- Pre-Generated Personalized LLM Coaching Impact
- Medical subject headings
- Motor Activity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Pre-Generated Personalized LLM Coaching ImpactBehavioural
After the initial 7 days, participants will switch to the other type of prompting for another 7 days. This means that participants who initially received personalized LLM-generated prompts will then receive generic activity prompts, and vice versa. This crossover design allows for each participant to experience both types of interventions, providing a within-subject comparison of the effectiveness of personalized versus generic prompts in increasing physical activity levels.
| Study group | Role | What they receive |
|---|---|---|
| Personalized LLM-Generated Coaching Prompts | Experimental | Not described Receives: Behavioral: Pre-Generated Personalized LLM Coaching Impact |
| Generic Activity Prompts | Active comparator | Not described Receives: Behavioral: Pre-Generated Personalized LLM Coaching Impact |
What is being measured
The primary outcome is the main question the study is designed to answer.
Physical Activity Levels
Measured: 14 days from enrollment
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted17 Mar 2025
- Study start20 Jan 2027 (estimated)
- Primary completion30 Jul 2027 (estimated)
- Study completion1 Dec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ExerciseStudies 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
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Enrolment
- 50 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Stanford University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Euan Ashley, Stanford University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06880315
- Sponsor's protocol ID
- 79946
- Status last verified
- Jul 2026
- First submitted
- 11 Mar 2025
- Last updated
- 23 Jul 2026
- Results posted
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 23 Jul 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Enhancing Physical Activity With LLM-Generated Coaching Prompts: A My Heart Counts Study
- ClinicalTrials.gov ID
- NCT06880315
- Acronym / sponsor ID
- 79946
- Conditions
- Exercise
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 50 participants (estimated)
- Lead sponsor
- Stanford UniversityUniversity, hospital or other
- Study start
- 20 Jan 2027 (estimated)
- Primary completion
- 30 Jul 2027 (estimated)
- Study completion
- 1 Dec 2027 (estimated)
- First posted
- 17 Mar 2025 (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.
This pilot study aims to evaluate whether personalized coaching prompts generated by a large language model (LLM) can effectively increase physical activity levels among participants. The study will involve 50 participants who will receive daily text messages, either personalized by the LLM or generic, over a 14-day period. Participants will share their HealthKit data for analysis. The findings will inform the development of future versions of the My Heart Counts application, enhancing user engagement and health outcomes.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Personalized LLM-Generated Coaching Prompts | Experimental | Behavioral: Pre-Generated Personalized LLM Coaching Impact |
| Generic Activity Prompts | Active comparator | Behavioral: Pre-Generated Personalized LLM Coaching Impact |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (5 listed)
- Age: Participants must be 18 years or older.
- Health Status: Participants must be healthy enough to engage in physical activity.
- Language Proficiency: Participants must be able to read, understand, and consent in English or Spanish (dependent on which is being studied).
- Device Ownership: Participants must possess an iPhone and an Apple Watch.
- Data Sharing: Participants must be willing to share their HealthKit data via secure upload.
Key exclusion criteria (5 listed)
- Age: Participants under the age of 18.
- Health Status: Participants who are not healthy enough to engage in physical activity.
- Language Proficiency: Participants who cannot read, understand, or consent in English or Spanish.
- Device Ownership: Participants who do not have both an iPhone and an Apple Watch.
- Data Sharing: Participants unwilling to share their HealthKit data via secure upload.
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 |
|---|---|---|
| Pre-Generated Personalized LLM Coaching ImpactAfter the initial 7 days, participants will switch to the other type of prompting for another 7 days. This means that participants who initially received personalized LLM-generated prompts will then receive generic activity prompts, and vice versa. This crossover design allows for each participant to experience both types of interventions, providing a within-subject comparison of the effectiveness of personalized versus generic prompts in increasing physical activity levels. | Behavioural | Generic Activity Prompts, Personalized LLM-Generated Coaching Prompts |
Primary outcome
Physical Activity Levels
Time frame: 14 days from enrollment
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 Jul 2026.
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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.
The record lists no contact. Use the official record to reach the sponsor.
Questions about this trial
What is this clinical trial studying?
A study testing Pre-Generated Personalized LLM Coaching Impact in people with Exercise, 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 5 inclusion and 5 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 Jul 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. 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?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Physical Activity Levels (time frame: 14 days from enrollment). 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 Jul 2026.