LAUSR

Abstract Objectives Mindfulness- and acceptance-based interventions (MABI) in sport settings need further development and validation to fulfil the desired outcomes related to sport performance. The current study aimed to design and implement a MABI integrated into the badminton training of young elite players (MBI programme), and to investigate its impact on sport performance-related outcomes. Design Two stages: (a) design and implementation of the MBI programme, and (b) evaluation using a mixed methods approach. Method Participants were young elite badminton players, assigned either to the 8-week MBI programme (n = 18; Mage = 16.22), or the 8-week placebo programme (n = 11; Mage = 16.64). Participants completed pre- and post-intervention measures of mindfulness skills, cognitive interference, and performance satisfaction. Social validation interviews were conducted with MBI participants to collect their overall perceptions of the programme. Results MANCOVA indicated a large intervention effect on the main outcome variables (partial η2 = 0.58). The results of univariate ANCOVAs showed that post-intervention awareness, performance worries and task-irrelevant thoughts differed significantly across the groups. In addition, follow-up t-tests provided additional information regarding changes from pre- to post-intervention among the MBI and control groups separately. Social validation data gave further insights into what athletes had retained and applied from the MBI programme. Conclusions Contrasting results highlighted the need to better explore mindfulness mechanisms in MABI and the way they are inter-related, in order to strengthen changes in sport performance-related outcomes.