The effects of performing therapeutic exercises and wearing minimalist shoes on intrinsic foot muscle function and single-leg balance in adults with plantar fasciopathy.

Abstract

Plantar fasciopathy (PF) results in decreased foot-muscle function and balance. The purpose was to investigate effects of performing exercises and wearing minimalist shoes on foot-muscle function and single-leg balance, compared to exercise-only in individuals with PF. Participants were randomly allocated into the Foot Rehabilitation and Minimalist ShoES (FRAMES)-group or control-group. Both groups performed exercises for 8 weeks; the FRAMES-group wore minimalist shoes. Outcome measures were collected at baseline and 8-weeks. Foot-muscle strength was assessed with a handheld-dynamometer and pulling-dynamometer for the great- and lesser-toes separately, for both limbs. Resting and resisted muscle-thickness and cross-sectional area (CSA) were assessed with ultrasound in a weight-bearing position for abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, and quadratus plantae. Single-leg-balance (eyes open and closed) assessed on a force plate indicated center of pressure distance, 95% ellipse area, average x and y deviations, and maximum velocity in all 4 directions. Repeated Measures Analysis of Variance tests assessed changes by time and group. 34 participants completed the intervention (FRAMES: n = 18 (13 female), Control: n = 16 (11 female)). All participants experienced significant increases in handheld-dynamometer great- and lesser-toes strength in both limbs (p < 0.001), pulling-dynamometer great-toe strength for non-PF (p = 0.035) and PF (p = 0.010) limbs, and quadratus plantae-CSA-resisted (p = 0.004). There was a significant interaction for flexor digitorum brevis-CSA-resisted (p = 0.009), with a significant decrease in the control-group; and no single-leg-balance changes. Individuals with PF who perform exercises with or without minimalist shoes for 8 weeks can significantly increase foot-muscle strength, but not foot-muscle size or balance. The study was registered on ClinicalTrials.gov as "Effects of Foot Rehabilitation And Minimalist Shoes on Pain, Strength, and Function in Adults With Plantar Fasciopathy (FRAMES)", (ID: NCT06106958).