title: Dynamic ankle control in athletes with ankle instability during sports maneuvers.
abstract: BACKGROUND
  Ankle sprain is a common sports injury. While the effects of static constraints in stabilizing the ankle joint are relatively well understood, those of dynamic constraints are less clear and require further investigation.
  
  
  OBJECTIVE
  This study was undertaken to evaluate the dynamic stability of the ankle joint during the landing phase of running and stop-jump maneuvers in athletes with and without chronic ankle instability (CAI).
  
  
  METHODS
  Controlled laboratory study.
  
  
  METHODS
  Fifteen athletes with CAI and 15 age-matched athletes without CAI performed running and stop-jump landing tasks. The dynamic ankle joint stiffness, tibialis anterior (TA)/peroneus longus (PL) and TA/gastrocnemius lateralis (GL) co-contraction indices, ankle joint angle, and root-mean-square (RMS) of the TA, PL, and GL electromyographic signals were measured during each task.
  
  
  RESULTS
  During running, the CAI group exhibited a greater ankle inversion angle than the control group in the pre-landing phase (P = .012-.042) and a lower dynamic ankle joint stiffness in the post-landing phase (CAI: 0.109 ± 0.039 N·m/deg; control: 0.150 ± 0.068 N·m/deg; P = .048). In the stop-jump landing task, athletes with CAI had a significantly lower TA/PL co-contraction index during the pre-landing phase (CAI: 49.1 ± 19; control: 64.8 ± 16; P = .009). In addition, the CAI group exhibited a greater ankle inversion (P = .049), a lower peak eversion (P = .04), and a smaller RMS of the PL electromyographic signal in the post-landing phase (CAI: 0.73 ± 0.32; control: 0.51 ± 0.22; P = .04).
  
  
  CONCLUSIONS
  Athletes with CAI had a relatively inverted ankle, reduced muscle co-contraction, and a lower dynamic stiffness in the ankle joint during the landing phase of sports maneuvers and this may jeopardize the stability of the ankle.
  
  
  CONCLUSIONS
  Sports training or rehabilitation programs should differentiate between the pre-landing and post-landing phases of sports maneuvers, and should educate athletes to land with an appropriate ankle position and muscle recruitment.
authors.affiliation: Department of Physical Therapy, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan. connie@mail.ncku.edu.tw
authors.forename: Cheng-Feng
authors.initials: CF
authors.lastname: Lin
authors.forename: Chin-Yang
authors.initials: CY
authors.lastname: Chen
authors.forename: Chia-Wei
authors.initials: CW
authors.lastname: Lin
mesh_terms: D000293:Adolescent; D000328:Adult; D000842:Ankle / Q000503:physiopathology*; D016512:Ankle Injuries / Q000503:physiopathology; D004576:Electromyography; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D012420:Running / Q000502:physiology*; D013180:Sprains and Strains / Q000503:physiopathology; D055815:Young Adult