Objectives: The aim of the study was to examine mediating effects of emotion regulation and sport-specific dispositional mindfulness on self-rated athletic training performance, following the Mindfulness-Acceptance-Commitment (MAC) intervention, compared to a Psychological Skills Training (PST) control group.

Methods: Sixty-nine competitive elite athletes who did not have any prior experience with mindfulness- and acceptance-based exercises, were recruited and randomly assigned into either a MAC group or a traditional PST group. Latent growth curve analyses were performed to examine longitudinal relationships among the study variables. Mediation analyses were conducted to test if the growth trajectory of each of the proposed mediators mediated the relationship between the intervention and perceived performance (measured at T3).

Results: Findings showed that the MAC intervention had an indirect effect on self-rated athletic training performance through changes in dispositional mindfulness and emotion regulation respectively. Further, the MAC- group obtained greater post-test improvements in athletic mindfulness, emotion regulation abilities, and perceived performance compared to the PST group.

Conclusions: Overall, findings suggest that dispositional athletic mindfulness and emotion regulation may function as important mechanisms in MAC, and that the MAC approach is a more effective intervention compared to the PST condition in reducing emotion regulation difficulties, as well as enhancing sport-relevant mindfulness skills and perceived athletic training performance in elite sport.