There is convincing evidence on the effects of sport and exercise on mental health and well-being. Less evidence is provided about how to achieve these benefits in the context of grassroots sport coaching. We systematically reviewed the scientific literature of three databases to narratively synthesize the current knowledge about which coaching-related factors influence well-being or ill-being, and how to promote mental health in adult athletes through sport coaches. The review includes 52 studies with different methodological and theoretical approaches and mental health outcomes. The wide range of themes were mapped and synthesized within two clusters, i.e., coaching behavior, antecedents, and context; and coach-athlete relationship and social support. The results highlight the importance of the promotion of empowering environments, autonomy-supportive coaching behavior, and coach-athlete relationship quality that relate to the satisfaction of basic psychological needs. The review also calls for a critical perspective, in the sense that the coaching context and working environment may not be empowering and supportive to the well-being of coaches and consequently to the athletes, and that coaches who want to provide autonomy-supportive environments may face various obstacles. Finally, the review synthesizes recommendations for the training of coaches, as one piece of a holistic mental health promotion.
Keywords: autonomy support; coaching behavior; coach–athlete relationship; grassroots; health promotion; mental health; needs; participation coach; self-determination; trainer.