RESUMEN
Unique risk factors for the development of muscle dissatisfaction and engagement in muscle-building behaviors have been described by theoretical frameworks and supported by empirical research. What remains unknown are the unique processes, including catalysts and facilitators, which underpin engagement in muscle-building behaviors. Therefore, this study used a grounded theory methodology to elucidate the process of engagement in muscle-building behaviors. Thirty-three individual semi-structured interviews with Canadian adolescents and young adults ages 16-30 years were conducted. Transcripts were analyzed using initial and focused coding to identify themes that explained the grounded theory. The core theme underpinning the grounded theory was balancing aesthetic, health, and functional goals in relation to participants' engagement in muscle-building behaviors. Participants described experiences that encompassed several unique phases of muscle-building engagement, including the initiation phase, beginner phase, preservation phase, and intensification phase. Participants also described unique methods of gathering information on muscle-building behaviors, and their own analysis and decision-making processes driving their behaviors. Findings from this study extend prior theory and research by conceptualizing a novel process theory of engagement in muscle-building behaviors among adolescent and young adults, resulting in important implications for research and practice.