Background: Research shows that pedometers help to increase daily physical activity. However, much less is known about why pedometers work, specifically as it relates to the theoretical grounding of pedometerbased interventions.Objectives: To complete a full review of the literature regarding the use of theory and specific skills/tools used in pedometer-based interventions as it relates to changes in behaviour across time.Methods: Thirty-one original theoretically-based intervention studies were identified to inform this review of theoretical constructs, intervention strategies, and pedometer contributions that influence walking behaviour.Results: Studies suggest that Social Cognitive Theory (SCT), specifically the behaviours of self-monitoring, feedback, and goal-setting are critical elements for an intervention. While the Theory of Planned Behaviour (TBP) successfully increases motivation, there is less evidence that changing motivation alone translates into behaviour change. However, adding the Implementation Intention (II) Theory appears to hold promise. Using behavioural techniques guided by the Transtheoretical Model (TTM) appear to provide benefit when considering population, the environment, and overcoming environmental barriers. Other and new integrated models are also emerging in this area, such as the small changes model (SCM). Conclusions: While the field of pedometer-based interventions holds significant potential to address the physical inactivity crisis, interventionists should use theory to guide intervention, consistent description of the theory, skills and tools used in an intervention, and reported step counts to compare interventions in order to advance the impact of this important area of research.

Using a small changes approach, participants achieved weight loss in an initial group-based program, which continued with minimal phone-based follow-up. Larger randomized studies comparing a small changes approach to traditional obesity treatment are warranted.