title: The effects of prolonged running on foot posture: a repeated measures study of half marathon runners using the foot posture index and navicular height.
abstract: BACKGROUND
  Different foot postures are associated with alterations in foot function, kinetics and the subsequent occurrence of injury. Little is known about changes in foot posture following prolonged weightbearing exercise. This study aimed to identify changes in foot posture after running a half marathon.
  
  
  METHODS
  Foot posture was measured using the Foot Posture Index (FPI-6) and navicular height in thirty volunteer participants before and after running a half marathon. FPI-6 scores were converted to Rasch logit values and means compared for these and navicular height using an ANOVA.
  
  
  RESULTS
  There was a 5 mm drop in navicular height in both feet when measured after the half marathon (P < 0.05). The FPI-6 showed a side x time interaction with an increase in score indicating a more 'pronated' position in the left foot of + 2 [Rasch value + 1.7] but no change in the right foot (+ 0.4 [+ 0.76]) following the half marathon.
  
  
  CONCLUSIONS
  The apparent differences between the FPI-6 and navicular height on the right foot may be because the FPI-6 takes soft tissue contour changes into consideration whilst the navicular height focuses on skeletal changes. The changes in foot posture towards a more pronated position may have implications for foot function, and therefore risk of injury; shoe fit and comfort and also the effect of therapeutic orthoses worn during prolonged running.
authors.affiliation: School of Health Professions, Plymouth University, Faculty of Health, Education and Society, Peninsula Allied Health Centre, Derriford Road, Plymouth, PL6 8BH, UK.
authors.forename: Emma
authors.initials: E
authors.lastname: Cowley
authors.affiliation: School of Health Professions, Plymouth University, Faculty of Health, Education and Society, Peninsula Allied Health Centre, Derriford Road, Plymouth, PL6 8BH, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Marsden
keywords: Fatigue; Foot posture; Half marathon; Navicular height; Prolonged; Pronation; Running