title: Fatigue Effect on Linear Center of Pressure Measures during Gait in People with Flat Feet.
abstract: BACKGROUND
  Flat foot, as one of the common foot deformities can affect gait biomechanics and risk of lower extremity injury. Fatigue, as a high load task, can also change biomechanical parameters of locomotion. Studying normal and flat footed individuals under high load tasks such as fatigue can elucidate their differences more easily.
  
  
  OBJECTIVE
  In this study, center of pressure (CoP) changes were studied between individuals with flat and normal feet after fatigue. CoP is one of the important gait measures which can show various biomechanical behaviors of different foot shapes.
  
  
  METHODS
  Seventeen subjects with normal feet and 17 with flat feet walked across two force plates before and after a functional fatigue protocol. Standard deviation of CoP in mediolateral direction (SD of CoPx) and in anteroposterior direction (SD of CoPy), overall mean velocity of CoP and length of CoP construction line of both groups were analyzed. The values of SD of CoPy and length of CoP construction line were normalized to individual foot lengths prior to statistical analyses.
  
  
  RESULTS
  There were no significant between-subject effects for all CoP measures. The only significant finding was the within-subject effect for the SD of CoPy (P = 0.008) with a large effect size (partial eta squared = 0.21). Fatigue resulted in lower SD of CoPy in both groups.
  
  
  CONCLUSIONS
  Lower SD of CoPy indicates less fluctuation of CoPy and a probable less center of mass movement which could reduce the risk of injury. Furthermore, the similar fatigue response in both groups of individuals with normal and flat feet indicates a similar biomechanical behavior despite their different foot arch height.
authors.affiliation: Rehabilitation Research Center, Biomechanics Lab, Department of Rehabilitation Basic Sciences, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Sanjari
authors.affiliation: Department of Physiotherapy, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Sahar
authors.initials: S
authors.lastname: Boozari
authors.affiliation: Rehabilitation Research Center, Department of Physiotherapy, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Ali
authors.initials: A
authors.lastname: Ashraf Jamshidi
authors.affiliation: Department of Rehabilitation Basic Sciences, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, IR Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Nikmaram
keywords: Fatigue; Flatfoot; Walking