BibTex format
@article{Schmiedmayer:2026:10.1016/j.ajpc.2026.101565,
author = {Schmiedmayer, P and Johnson, A and Schuetz, N and Kollmer, L and Goldschmidt, P and Delgado-SanMartin, J and Zhang, KW and Mantena, SD and Tolas, A and Montalvo, S and Ramirez-Posada, M and O'Sullivan, JW and Oppezzo, M and King, AC and Rodriguez, F and Ashley, E and Lawrie, A and Kim, DS},
doi = {10.1016/j.ajpc.2026.101565},
journal = {Am J Prev Cardiol},
title = {Design and rationale of the my heart counts cardiovascular health study: a large-scale, fully digital biobank, and randomized trial of large language model-driven coaching of physical activity.},
url = {http://dx.doi.org/10.1016/j.ajpc.2026.101565},
volume = {28},
year = {2026}
}
RIS format (EndNote, RefMan)
TY - JOUR
AB - BACKGROUND: Cardiovascular disease remains the leading cause of global morbidity and mortality. The original My Heart Counts smartphone application demonstrated the feasibility of large-scale, fully digital recruitment and trial conduct, but was limited by platform exclusivity and the need for human experts to create text-based behavioral interventions. METHODS: The next-generation My Heart Counts smartphone application is a prospective, observational cohort study with an embedded randomized crossover trial, evaluating personalized text-based coaching prompts, available in both English and Spanish. All study and trial operations will be conducted via the My Heart Counts smartphone application, re-designed using the open-source Stanford Spezi framework to support iOS, with a planned Android release in 2027. The target enrollment is N = 15,000 adults across the United States and United Kingdom. The study establishes a comprehensive digital biobank by synthesizing passive mobile health data (steps, flights climbed, heart rate, sleep, workouts), raw sensor data (e.g., accelerometry), longitudinal clinical surveys, active tasks (6-minute walk test and 12-minute Cooper run test), electrocardiograms (ECG), and electronic health record (EHR) data integrated via HL7 FHIR protocols. The embedded trial evaluates the effect of text-based coaching prompts generated by a large language model (LLM) grounded in the Transtheoretical Model of Change on daily physical activity, as compared to generic prompts. PLANNED ANALYSIS: The primary endpoint of the randomized crossover trial is change in daily step count between LLM-driven and generic text-based intervention arms, analyzed using mixed-effects models. Secondary endpoints include change in mean active minutes and calorie burn over each intervention week. Other exploratory analyses include the changes in submaximal (6-minute walk test) and maximal (Cooper 12-minute run test) cardiorespiratory fitness, changes to sensor-derived biom
AU - Schmiedmayer,P
AU - Johnson,A
AU - Schuetz,N
AU - Kollmer,L
AU - Goldschmidt,P
AU - Delgado-SanMartin,J
AU - Zhang,KW
AU - Mantena,SD
AU - Tolas,A
AU - Montalvo,S
AU - Ramirez-Posada,M
AU - O'Sullivan,JW
AU - Oppezzo,M
AU - King,AC
AU - Rodriguez,F
AU - Ashley,E
AU - Lawrie,A
AU - Kim,DS
DO - 10.1016/j.ajpc.2026.101565
PY - 2026///
TI - Design and rationale of the my heart counts cardiovascular health study: a large-scale, fully digital biobank, and randomized trial of large language model-driven coaching of physical activity.
T2 - Am J Prev Cardiol
UR - http://dx.doi.org/10.1016/j.ajpc.2026.101565
UR - https://www.ncbi.nlm.nih.gov/pubmed/42395096
VL - 28
ER -