NCT06880315

LLM-Generated Coaching Prompts

Enhancing Physical Activity With LLM-Generated Coaching Prompts: A My Heart Counts Study

• Status: Not Yet Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 50 (estimated)
• Sponsor: Stanford University · Academic / Other
• Sex: All
• Age: 18 Years
• Healthy volunteers: Accepted

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. 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

Interventions

Type	Name	Description
BEHAVIORAL	Pre-Generated Personalized LLM Coaching Impact	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.

Timeline

• Start date: 2026-02-20
• Primary completion: 2026-07-30
• Completion: 2026-12-01
• First posted: 2025-03-17
• Last updated: 2026-01-23