title: Dance floor force reduction influences ankle loads in dancers during drop landings.
abstract: OBJECTIVE
  Dance floor mechanical properties have the potential to influence the high frequency of ankle injuries in dancers. However, biomechanical risk factors for injury during human movement on hard, low force reduction floors have not been established. The aim of this study was to examine the ankle joint mechanics of dancers performing drop landings on dance floors with varied levels of force reduction.
  
  
  METHODS
  Repeated measures cross sectional study.
  
  
  METHODS
  Fourteen dancers performed drop landings on five custom built dance floors. Ankle joint mechanics were calculated using a three dimensional kinematic model and inverse dynamics approach.
  
  
  RESULTS
  Ankle joint kinematic (dorsiflexion; range of motion, peak angular velocity and acceleration) and kinetic (plantar flexion; peak joint moments and power) variables significantly increased with a decrease in floor force reduction. Many of the observed changes occurred within a latency of <0.1s post-contact with the floor and were associated with increased vertical ground reaction forces and decreased floor vertical deformation.
  
  
  CONCLUSIONS
  The observed mechanical changes are interpreted as an increase in the load experienced by the energy absorbing structures that cross the ankle. The short latency of the changes represents a high intensity movement at the ankle during a period of limited cognitive neuromuscular control. It is suggested that these observations may have injury risk implications for dancers that are related to joint stabilization. These findings may be of benefit for further investigation of dance injury prevention and support the notion that bespoke force reduction standards for dance floors are necessary.
authors: School of Health Sciences, University of Notre Dame Australia, Australia; Western Australian Academy of Performing Arts, Edith Cowan University, Australia. Electronic address: luke.hopper@nd.edu.au.
authors: Luke S
authors: LS
authors: Hopper
authors: School of Sport Science, Exercise and Health, University of Western Australia, Australia.
authors: Jacqueline A
authors: JA
authors: Alderson
authors: School of Sport Science, Exercise and Health, University of Western Australia, Australia.
authors: Bruce C
authors: BC
authors: Elliott
authors: School of Sport Science, Exercise and Health, University of Western Australia, Australia.
authors: Timothy R
authors: TR
authors: Ackland
mesh_terms: D000293:Adolescent; D000328:Adult; D016512:Ankle Injuries / Q000209:etiology; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D003430:Cross-Sectional Studies; D003615:Dancing / Q000502:physiology*; D005260:Female; D005430:Floors and Floorcoverings; D005528:Foot / Q000502:physiology; D006801:Humans; D008297:Male; D012307:Risk Factors; D013499:Surface Properties; D016474:Weight-Bearing / Q000502:physiology*; D055815:Young Adult
keywords: Ankle sprains; Injury risk; Joint instability; Sports floors; Tendinopathy