title: Functional knee brace use effect on peak vertical ground reaction forces during drop jump landing.
abstract: OBJECTIVE
  The aim of the study was to investigate the landing strategies used by non-injured athletes while wearing functional knee braces (FKB, BR condition) during a drop jump task compared with non-injured, non-braced (NBR condition) subjects and also to ascertain whether accommodation to a FKB was possible by non-injured BR subjects.
  
  
  METHODS
  Twenty-three healthy male provincial and national basketball and field hockey athletes (age, 19.4 ± 3.0 years) were tested. Each subject was provided with a custom-fitted FKB. Five NBR testing sessions were performed over 3 days followed by five BR testing sessions also over 3 days, for a total of 17.5 h of testing per condition. Each subject performed eight trials of the drop jump task during each testing session per condition. Single-leg peak vertical ground reaction forces (PVGRF) and the time to PVGRF were recorded for each NBR and BR trail.
  
  
  RESULTS
  The BR group mean PVGRF at landing was significantly lower (1,628 ± 405 N, 2.1 ± 0.5 BW versus 1,715 ± 403 N, 2.2 ± 0.5 BW, F (1,22) = 6.83, P = 0.01) compared with NBR subjects, respectively. The group mean time to PVGRF was not statistically longer during the BR condition (F (1,22) = 0.967, P = 0.3). Further, an accommodation trend was noted as percent performance difference decreased with continued FKB use.
  
  
  CONCLUSIONS
  The significantly lower group mean PVGRF while using a FKB could keep traumatic forces from reaching the ACL until the active neuromuscular restraints are activated to provide protection to the knee joint ligaments. Also, accommodation to FKB is possible after approximately 14.0 h of brace use. The results of this paper will assist clinicians in providing information to their patients regarding a FKB ability to offer protection to an ACL-deficient knee or to address concerns about early muscle fatigue, energy expenditure, heart rate, and decrease in performance level.
  
  
  METHODS
  Prospective study, Level I.
authors.affiliation: ACTIN Health and Rehabilitation Inc., 5767 Oak Street, Vancouver, BC, V6M 2V7, Canada.
authors.forename: Neetu
authors.initials: N
authors.lastname: Rishiraj
authors.forename: Jack E
authors.initials: JE
authors.lastname: Taunton
authors.forename: Robert
authors.initials: R
authors.lastname: Lloyd-Smith
authors.forename: William
authors.initials: W
authors.lastname: Regan
authors.forename: Brian
authors.initials: B
authors.lastname: Niven
authors.forename: Robert
authors.initials: R
authors.lastname: Woollard
mesh_terms: D000328:Adult; D001490:Basketball / Q000502:physiology*; D001696:Biomechanical Phenomena; D001915:Braces; D064368:Healthy Volunteers; D006688:Hockey / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D011446:Prospective Studies; D013647:Task Performance and Analysis