Energetics of the intrinsic foot muscles in plantar fasciitis

Introduction Intrinsic foot muscles and the plantar fascia provide mechanical support for the medial longitudinal arch in gait [1]. In an injury to the plantar fascia (i.e. plantar fasciitis), there may be an increase in load on the intrinsic foot muscles resulting in increased metabolic demand. Phosphorus magnetic resonance spectroscopy (31P MRS) has shown that the ratio of inorganic phosphate to phosphocreatine ([Pi]/[PCr]) within a muscle increases proportionately with muscle work at low to moderate levels [2]. The purpose of this study was to determine whether walking elicits a relatively higher increase in activity of the intrinsic foot muscles of feet with plantar fasciitis relative to healthy feet.