Effects of intrinsic foot muscle strengthening on the medial longitudinal arch mobility and function: A systematic review

Objective: To Investigate the effects of intrinsic foot muscle (IFM) strengthening on foot's medial longitudinal arch (MLA) mobility and function in healthy individuals. We also identified exercise type and resistance training characteristics (series and repetitions). Methods: Eight databases were searched, between October 2020 and February 2021 and updated in May 2021. We included randomized controlled trials involving IFM strengthening exercises compared with controls (no exercise or exercises not involving isolated intrinsic foot muscle strengthening). Methodological quality of the studies was assessed using PEDro scale and Cochrane Risk of Bias tool. Quality of evidence was evaluated using GRADE model (Grading of Recommendations, Assessment, Development and Evaluations). Results: Four randomized controlled trials (RCT) were included. IFM strengthening did not change MLA mobility in the short-term (4 weeks); however, it promoted medium-term effects (8 weeks - low quality of evidence). IFM exercises improved function in the short and medium-term (low quality of evidence). Most studies used the shortfoot exercise and the toe-towel curl exercise with contractions of 5 s and load progression from sitting to standing. Conclusion: IFM strengthening exercises change MLA mobility in the medium-term (8 weeks) and improve the dynamic balance of healthy individuals in short- (4 weeks) and medium-terms.