Mental Imagery Training Programs for Developing Sport-Specific Motor Skills: A Systematic Review and Meta-Analysis

Background: Physical practice is the cornerstone of acquiring and developing movement skills in physical education and sport. However, research has suggested that psychological tools, such as mental imagery (MI), could effectively supplement a learner's physical practice schedule. MI is the mental simulation of a movement or situation in the absence of an overt physical output. Previous reviews have established the efficacy of MI for improving motor skills in sport. Further investigation, however, will help strengthen previous findings by focusing exclusively on studies that apply MI programs for the development of sport-specific motor skills. Purpose: The purpose of this paper is to examine the overall effectiveness of MI programs for developing sport-specific motor skills and investigate program principles that may moderate the efficacy of MI programs, such as practice type, skill level, skill complexity, performance measures, duration, practice setting, and session frequency. By examining key program variables for MI, this review seeks to provide practical recommendations for physical educators and sports coaches on how they might effectively design and deliver a MI program to develop sport-specific motor skills. Method: The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. To provide practical recommendations for physical educators and sports coaches for effective MI programs, the following moderator variables were examined using subgroup analysis: (1) skill complexity; (2) skill level; (3) program duration; (4) session frequency; (5) MI practice type; and (6) practice context. The PEDro scale was used to assess study quality. The presence of publication bias was evaluated using the Trim and Fill method to calculate an adjusted and unbiased overall effect. Results: The systematic review included 36 studies (n = 1449). A random-effects meta-analysis of standardised mean differences yielded an initial 135 individual effect sizes. A composite approach accounted for statistical dependence between effects and yielded 58 individual effects for further analysis. Analysis indicated that MI has a significant effect on performance (g = 0.476). Further analysis revealed significant effects on performance outcomes for MI combined with physical practice and MI alone (g = 0.579 and 0.298, respectively). Subgroup analyses revealed these beneficial effects be moderated by skill complexity, elements of skill performance, and MI delivery type. Conclusions and recommendations: These results presented in our meta-analysis highlight the overall benefit of MI practice for developing sport-specific motor skills. However, there is a paucity of research on the effects of MI on complex skills and in physical education and sport coaching contexts. Although most studies presented in this review were conducted in controlled research settings, there are clear parallels between the skills practiced in these studies and those implemented in physical education and sport coaching. The efficacy of MI alone presents a potentially beneficial tool when physical practice is not possible or when physical training needs reduction (e.g. in-season sports competition). Therefore, it is encouraged that physical educators and sports coaches collaborate with sport psychology practitioners to investigate the efficacy of the several MI program variables presented in this review.