This is a pilot RCT examining physical activity outcomes at 3 months across 3 conditions: use of large language model (LLM) fully self-directed; use of LLM with guidance; and use of online tools to help with sleep.

To prepare for a future fully powered RCT, we are conducting a pilot RCT. The pilot RCT will enroll n=39 insufficiently active primary care patients, and randomize them to one of 3 conditions: LLM alone condition: participants are recommended to use a publicly available, general-purpose LLM for physical activity promotion over the next 3 months (n=13); LLM enhanced condition: participants are recommended to use a publicly available, general-purpose LLM for physical activity promotion over the next 3 months and additionally attend an initial session providing guidance on LLM use and weekly text message with suggestions on using the LLM (n=13); or Control condition: participants are recommended to use publicly available tools to help with sleep (websites with tips for sleep and guided meditation videos) over the next 3 months (n=13). At study onset, all participants will be given basic information about exercise safety. At 3 months, moderate-to-vigorous physical activity will be measured with a validated self-report measure. Feasibility and acceptability outcomes such as recruitment and retention--metrics essential for advancing to a subsequent large-scale trial-will be measured.

Inclusion Criteria:

• Age 18-75
• Reports a desire to increase physical activity level
• Not meeting minimum aerobic PA as indicated by L-CAT endorsement indicating level of activity below moderate (moderate defined as >= 5x/week activity or higher)
• Reports willingness to use LLMs to help with exercise goals.
• Access to internet through phone data plan or home Wi-Fi.

Exclusion Criteria:

• Conditions warranting more extensive supervision of physical activity, including:

  • Any history of MI or stroke, arrhythmias, or heart failure
  • Uncontrolled hypertension
  • Type 1 or 2 diabetes
  • COPD or asthma
  • Recent orthopedic surgery or fracture
  • Advanced Parkinson's
  • Pregnant or planning to become pregnant in next 9 months
  • Active cancer undergoing treatment
  • Recent major surgery (<12 weeks)
  • Use of assistive devices for ambulation
  • History of eating disorder diagnosis

• Dementia diagnosis

• Unable to read on own.

• Hospitalization for mental health reasons in past year

• Has used LLM to support physical activity goals in prior 3 months.

• Currently enrolled in a structured program to promote physical activity or weight loss.