Advancing Behavioral Intervention and Theory Development for Mobile Health: The Heart Steps II Protocol

Donna Spruijt-Metz, Benjamin M. Marlin, Misha Pavel, Daniel E. Rivera, Eric Hekler, Steven De La Torre, Mohamed El Mistiri, Natalie M. Golaszweski, Cynthia Li, Rebecca Braga De Braganca, Karine Tung, Rachael Kha, Predrag Klasnja

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Background: Recent advances in mobile and wearable technologies have led to new forms of interventions, called “Just-in-Time Adaptive Interventions” (JITAI). JITAIs interact with the individual at the most appropriate time and provide the most appropriate support depending on the continu-ously acquired Intensive Longitudinal Data (ILD) on participant physiology, behavior, and contexts. These advances raise an important question: How do we model these data to better understand and intervene on health behaviors? The HeartSteps II study, described here, is a Micro-Randomized Trial (MRT) intended to advance both intervention development and theory-building enabled by the new generation of mobile and wearable technology. Methods: The study involves a year-long deployment of HeartSteps, a JITAI for physical activity and sedentary behavior, with 96 sedentary, overweight, but otherwise healthy adults. The central purpose is twofold: (1) to support the development of modeling approaches for operationalizing dynamic, mathematically rigorous theories of health behavior; and (2) to serve as a testbed for the development of learning algorithms that JITAIs can use to individualize intervention provision in real time at multiple timescales. Discussion and Conclusions: We outline an innovative modeling paradigm to model and use ILD in real-or near-time to individually tailor JITIAs.

Original languageEnglish (US)
Article number2267
JournalInternational journal of environmental research and public health
Issue number4
StatePublished - Feb 1 2022


  • Behavioral health
  • Digital health
  • Intensive longitudinal data
  • MHealth
  • Mobile Health
  • New technologies
  • Physical activity
  • Psychosocial theory
  • Real-time interventions

ASJC Scopus subject areas

  • Pollution
  • Public Health, Environmental and Occupational Health
  • Health, Toxicology and Mutagenesis


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