Effects of a mindfulness intervention on pre-competition mental states in youth athletes: a randomized controlled trial

Introduction Adolescent athletes face heightened pre-competition stress, yet evidence on mindfulness interventions for this population remains limited to isolated psychological outcomes. This study examined the effects of a mindfulness-based intervention on three pre-competition mental states–anxiety, sleep quality, and psychological resilience–while testing sport type and baseline anxiety as moderators. Methods A randomized controlled trial was conducted with 120 adolescent athletes (aged 14–18 years) recruited from three specialized sport schools. Participants were randomized to an 8-week multicomponent mindfulness program (weekly group sessions plus daily practices, n = 60) or to an active sport-psychology education control ( n = 60). Outcomes were assessed at baseline (T1), post-intervention (T2), and 4-week follow-up (T3). Results The intervention produced significant improvements across all three outcomes (anxiety: –14.45 points, η 2 p = 0.23; sleep quality: –3.11 points, η 2 p = 0.20; resilience: +15.92 points, η 2 p = 0.17), with no significant changes in the control group. Individual-sport athletes showed stronger responses than team-sport athletes (η 2 p = 0.20–0.25 vs 0.15–0.18), and moderation analyses indicated that athletes with higher baseline anxiety derived greater gains in sleep quality and resilience. Exploratory mediation suggested that increased mindfulness statistically accounted for approximately 28% of the intervention effect; however, mediator and outcomes were assessed at the same post-intervention time point, limiting causal inference. All gains were maintained at the 4-week follow-up. Discussion Findings identify sport type and baseline anxiety as key predictors of mindfulness intervention effectiveness in youth athletes, offering practical guidance for tailoring mindfulness training in youth sports contexts. Results should be interpreted in light of the multicomponent design, the short follow-up, reliance on.