Rehabilitation Exercises And Minimalist Shoes Strengthen Intrinsic Foot Muscles In Adults With Plantar Fasciopathy

The plantar fascia and the intrinsic foot muscles (IFM) provide stability to the foot, yet individuals with plantar fasciopathy (PF) have reduced intrinsic foot muscle (IFM) strength. Several studies have shown that IFM strengthening, via exercises or wearing minimalist shoes, leads to reduced pain in individuals with PF, but few studies have investigated changes in IFM strength. PURPOSE: The purpose of this study was to investigate the effects of an 8-week intervention of exercise and wearing minimalist shoes (MS), compared to only exercise, on IFM strength of the painful foot in adults with PF. METHODS: Thirty-three individuals with PF were randomized into an exercise plus MS group (n = 17, 12 female) or exercise only control group (n = 16, 11 female). IFM strength was assessed at baseline and follow-up with a handheld dynamometer, in a hook lying position on a treatment table with toes off the table. Participants were instructed to push down on the transducer with the great and lesser toes, separately. Maximal isometric contraction was recorded in Newtons. Participants were instructed in home exercises including massage ball myofascial release, toes-elevated calf raises, and calf and foot stretches. Participants in the MS group were also instructed to wear MS daily with progressing daily wear time throughout the intervention. Repeated measures ANOVAs evaluated the interaction of group and time on IFM strength, with Tukey’s HSD post-hoc testing when appropriate. α = 0.05 for all analyses. RESULTS: Participants had similar baseline characteristics (age: 39.7 ± 12.0, height: 167 cm ± 8.71, weight: 77.1 kg ± 13.1). There were significant time main effects for great toe IFM strength (p < 0.001; control: baseline 86.33 N ± 46.21, follow-up 112.82 N ± 45.22; MS: baseline 73.77 N ± 30.71, follow up 100.06 N ± 37.18) and lesser toe IFM strength (p < 0.001; control: baseline 74.36 N ± 38.06, follow-up 96.43 N ± 35.41; MS: baseline 57.09 N ± 26.78, follow-up 78.97 N ± 27.57), but no between group differences. CONCLUSIONS: Performing rehabilitation exercises with or without wearing MS led to improved IFM strength, potentially indicating that individuals with PF can increase function alongside decreases in pain. Although adding MS did not produce superior strength gains, individuals with PF may wear MS if desired without any adverse effects. Supported by: This study has been funded by the Xero Shoes Minimal Footwear Research Grant through ACSM