The Effect of Mental Imagery Practice on Maximal Voluntary Strength: A Meta-Analysis and Systematic Review

Motor Imagery (MI), an internal visualization of the movement of an appendage or the contraction of a muscle, has been shown to improve motor skills. However, the effects of MI to improve maximal voluntary strength (MVS) has been questionable as previous meta-analyses have contradicting conclusions. The purpose of the current study was to provide an evidence-based synthesis of the published research articles and thesis/dissertations in English from January 1990 to October 2021 in the area of the effect of motor imagery on enhancing muscle strength for both young adults (18 years to 50 years) and older adults (65 years and older). Following the guidelines set by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis Protocols, seven electronic databases were searched for relevant randomized control trial studies. Studies were screened for inclusion, and the pertinent data was collected and analyzed. Compared to the untrained control group (CNTRL), MI practice had a moderate improvement to MVS in the younger group. The results for the older group suggest that MI training tentatively has a positive benefit on MVS, but the final finding is inconclusive. This suggests that MI practice might be a beneficial tool to preserve or improve muscle strength in older adults, however, due to the limited number of studies further research is needed to determine its efficacy.