Building and strengthening physical activity identity: a theory-informed user-guide

Physical activity identity, or viewing oneself as a physically active person, reliably predicts physical activity. Yet, little is known about how physical activity identity can be developed or strengthened. In this critical narrative review, we conducted a comprehensive literature search to identify models of physical activity identity, health psychology, behaviour change, identity or self-related constructs in search of explanations, constructs, or insights important for physical activity identity building and strengthening. Identified models included: the physical activity self-definition model, maintain IT, M-PAC, PRIME, possible selves, and self-determination theory. Using content analysis, we identified themes around candidate antecedents of physical activity identity. Nine common physical activity identity inputs were identified that we categorised as behavioural (physical activity; self-regulation; investment), cognitive (perceived ability; imaginal experiences, rules/standards; alignment with goals or values) or social (attachment ties; social appraisals). For each candidate input, we identify which models include the input, consider relevant research, discuss how and why the input may be related to physical activity identity, and offer practical strategies for building or strengthening physical activity identity. We offer a list of theory-informed physical activity identity inputs, a working figure which represents these identity inputs, and suggestions about how they may relate to physical activity identity (directly; indirectly). We aim to support future researchers in advancing the physical activity identity literature, and help practitioners support physical activity behaviour change.