Study protocol for a sequential multiple assignment randomized trial (SMART) to improve physical activity in employed women

Contemp Clin Trials. 2020 Feb;89:105921. doi: 10.1016/j.cct.2019.105921. Epub 2019 Dec 30.


Introduction: Physical activity monitors, motivational text messages, personal calls, and group meetings, have proven to be efficacious physical activity interventions. However, individual participant response to these interventions varies drastically. A SMART design (sequential multiple assignment randomized trial) provides an effective way to test interventions that start with an initial treatment and then transition to an augmented treatment for non-responders. We describe a SMART to determine the most effective adaptive intervention to increase physical activity (steps, moderate-to-vigorous physical activity) and improve cardiovascular health among employed women who are not regularly physically active. The SMART uses combinations of four treatments: 1) enhanced physical activity monitor (Fitbit wearable activity monitor and mobile app with goal setting and physical activity prescription), 2) text messages, 3) personal calls, and 4) group meetings.

Methods: Participants (N = 312) include women ages 18-70 employed at a large academic medical center. Women will be randomized to an initial intervention, either an enhanced physical activity monitor or enhanced physical activity monitor + text messaging. Non-responders to the initial intervention at 2 months will be randomized to either personal calls or groups meetings for the next 6 months. At 8 months, all participants will return to only an enhanced physical activity monitor until their final 12-month assessment.

Discussion: Results of this study will add to the literature on improving physical activity in employed women. This study will identify effective interventions for women who respond to less intensive treatments, while maximizing benefits for those who need a more intensive approach.

Keywords: Adaptive interventions; Fitbit; Physical activity; SMART; Sequential multiple assignment randomized trial; Women.

Publication types

  • Clinical Trial Protocol
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Academic Medical Centers
  • Adolescent
  • Adult
  • Aged
  • Exercise / physiology*
  • Female
  • Fitness Trackers
  • Health Promotion / organization & administration*
  • Humans
  • Middle Aged
  • Research Design
  • Social Support
  • Text Messaging
  • Women, Working*
  • Young Adult