A Systematic Review Examining the Relationship Between Habit and Physical Activity Behavior in Longitudinal Studies

Purpose: To explain PA behavior, social-cognitive theories were most commonly used in the past. Besides conscious processes, the approach of a dual system additionally incorporates non-conscious regulatory processes into PA behavior theories. Habits are one of various non-conscious variables that can influence behavior and thus play an important role in terms of behavior change. The aim of this review was to examine the relationship between habit strength and PA behavior in longitudinal studies. Methods: According to the PRISMA guidelines, a systematic search was conducted in three databases. Only peer-reviewed articles using a longitudinal study design were included. Both, habit and PA were measured at least once, and habit was related to PA behavior. Study quality was evaluated by assessment tools of the NHLBI. Results: Fifteen of 3.382 identified publications between 2016 and 2019 were included. Most studies supported that positive correlations between habit and PA exist. Positive direct effects of habit on PA were detected in only two studies while several other studies present indirect effects. Only one study revealed PA to influence habit strength and two other studies showed the effect of PA interventions to increase habit. One study applied a cross-lagged panel design to answer both directions of effect and reported inconclusive results. A distinction between instigation and execution habit was conducted in three studies, which showed positive correlations for both habit variables and PA. Studies showed that the relationship between instigation habit and PA is stronger than between execution habit and PA. The quality of studies was rated as reasonable using assessment tolls of the NHLBI. Conclusion: This review revealed a bidirectional relationship between habit and PA. Whether habit predicts PA or vice versa is still unclear. The observation of habit influencing PA may be most appropriate in studies fostering PA maintenance while the influence of PA on habit may be reasonable in experimental studies with PA as intervention content to form a habit. Future investigations should differentiate between habit formation and PA maintenance studies dependent on the research objective. Further, more long-term studies are needed to satisfactorily examine the relationship between habit and PA.