A developmental perspective on appearance-related social media use, body dissatisfaction, and competitive anxiety among Chinese adolescent athletes: a three-wave longitudinal study

Introduction Digital media engagement centered on appearance has become ubiquitous among adolescents, yet its developmental trajectory and age-specific psychological impacts on young athletes remain poorly understood. This study investigates age-related differences in the longitudinal relationships between appearance-related social media use (ARSME), body dissatisfaction (BD), and competitive anxiety (CA) among Chinese adolescent athletes (aged 14–18) across aesthetic/weight-class and non-leanness sports. The developmental psychopathology framework was adopted because adolescence encompasses distinct developmental phases characterized by differential sensitivity to social-evaluative environmental influences, making a developmental lens essential for understanding age-specific vulnerability to appearance-focused digital content. Methods A 12-month, three-wave longitudinal study was conducted with 356 Chinese adolescent athletes (184 males, 172 females; 14–18 years). Participants were categorized into younger (14–16 years, n = 200) and older (17–18 years, n = 156) groups. Cross-lagged panel modeling (CLPM), random intercept CLPM (RI-CLPM), and multi-group analyses were employed, controlling for sport type (aesthetic/weight-class vs. other sports). Results Younger adolescents exhibited significantly higher levels of ARSME ( d = 0.26–0.37), body dissatisfaction ( d = 0.29–0.45), and competitive anxiety ( d = 0.24–0.30). Age moderated the ARSME → body dissatisfaction pathway (Δχ 2 = 5.28, p = 0.022), with stronger effects in younger ( β = 0.22) than older ( β = 0.13) athletes. Body dissatisfaction mediated 61% of the ARSME–competitive anxiety relationship in younger versus 30% in older adolescents. A supplementary sensitivity analysis decomposing ARSME into behavioral engagement and psychological investment components revealed that psychological investment showed a marginally significant prospective effect on body dissatisfaction ( β = 0.08, p = 0.066), while behavioral screen time did not, providing preliminary support for cognitive-processing-focused interventions. Effects remained significant after controlling for sport type. Conclusion Younger adolescent athletes (14–16 years) represent a critical period of heightened vulnerability. Prevention-focused interventions for younger adolescents should prioritize cognitive reappraisal training, metacognitive awareness skills, and functionality-focused body appreciation rather than mere screen time reduction. For older adolescents (17–18 years), interventions targeting performance-based social comparison and authentic self-presentation are additionally warranted.