title: The relationship among foot posture, core and lower extremity muscle function, and postural stability.
abstract: BACKGROUND
  Identification of impaired balance as a risk factor for lower extremity injury regardless of injury history has led to subsequent investigation of variables that may adversely affect balance in healthy individuals.
  
  
  OBJECTIVE
  To investigate the relationship among core and lower extremity muscle function, foot posture, and balance.
  
  
  METHODS
  Descriptive laboratory study.
  
  
  METHODS
  Musculoskeletal injury biomechanics laboratory.
  
  
  METHODS
  A total of 108 individuals (40 men, 68 women; age = 22.8 ± 4.7 years, height = 168.5 ± 10.4 cm, mass = 69.9 ± 13.3 kg) participated in the study.
  
  
  METHODS
  Core endurance was assessed during 1 time-to-failure trial, and isometric hip and ankle strength were assessed using a handheld dynamometer and isokinetic dynamometer, respectively. Foot structure was quantified using the digital photographic measurement method. Single-limb-stance time to boundary was assessed using a force plate during an eyes-closed condition. Hierarchical multiple regression analyses were performed to predict balance using lower extremity strength, foot posture, and core endurance.
  
  
  RESULTS
  Foot posture (β = -0.22, P = .03) and ankle-inversion strength (β = -0.29, P = .006) predicted mediolateral balance. Increasing arch posture and ankle-inversion strength were associated with decreased mediolateral single-limb-stance balance.
  
  
  CONCLUSIONS
  Increasing arch height was associated with decreased mediolateral control of single-limb stance. The relationship between time to boundary and injury risk, however, has not been explored. Therefore, the relationship between increasing arch height and injury due to postural instability cannot be determined from this study. If authors of future prospective studies identify a relationship between decreased time to boundary and increased injury risk, foot structure may be an important variable to assess during preparticipation physical examinations. The relationship between increasing ankle-inversion strength and decreased balance may require additional study to further elucidate the relationship between ankle strength and balance.
authors.affiliation: Department of Kinesiology, University of Wisconsin-Milwaukee.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Cobb
authors.forename: David M
authors.initials: DM
authors.lastname: Bazett-Jones
authors.forename: Mukta N
authors.initials: MN
authors.lastname: Joshi
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: Earl-Boehm
authors.forename: C Roger
authors.initials: CR
authors.lastname: James
mesh_terms: D000328:Adult; D000842:Ankle / Q000502:physiology; D015992:Body Mass Index; D005260:Female; D005528:Foot / Q000502:physiology*; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D011403:Pronation / Q000502:physiology; D055815:Young Adult