"Eat more protein, build more muscle": A grounded theory study of muscle-building behaviors among Canadian adolescents and young adults.

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.

Associations between social media use, fitness- and weight-related online content, and use of legal appearance- and performance-enhancing drugs and substances.

Prior research has documented the connection between social media use and engaging with fitspiration with body dissatisfaction, disordered eating behaviors, and various health risk behaviors (e.g., substance use). However, gaps remain in the knowledge base on whether social media use and engaging with fitness- and weight-related online content are associated with the use of legal appearance- and performance-enhancing drugs and substances (APEDS; e.g., whey protein), which was the aim of this study. Data from participants ages 16-30 years in Canadian Study of Adolescent Health Behaviors (N = 2731) were analyzed. Multiple modified Poisson regression analyses were conducted to determine the associations between hours per day of social media use and any engagement with fitness- and weight-related online content in the past 30 days and use of 10 different legal APEDS in the past 30 days. Greater time on social media was significantly associated with use of energy drinks and pre-workout drinks or powders in the past 30 days. Engaging with fitness- and weight-related online content was significantly associated with the use of caffeine, creatine monohydrate, pre-workout drinks or powders, probiotics, protein bars, and whey protein powders or shakes in the past 30 days. These findings expand prior research on the correlates of social media use and engagement with fitness- and weight-related online content among young people and have important implications for healthcare and public health professionals, as well as technology companies.