Collegiate Dancers With Chronic Ankle Instability Possess Altered Strength and saut de chat Leap Landing Mechanics

Introduction: Ankle sprains are among the most common injuries in dancers. Following one or more severe sprains, some individuals will experience residual mechanical and functional deficits, otherwise known as chronic ankle instability (CAI). Dancers who suffer from CAI may have weaker musculature surrounding the ankle and altered landing mechanics. The purpose of this study was to compare ankle strength and saut de chat landing mechanics between dancers with and without CAI. Methods: Dancers with and without CAI, defined by the Identification of Functional Ankle Instability (IdFAI), participated in the study (CAI n = 8; IdFAI = 18.75 +/- 5.50 points; age = 20 +/- 1.5 years; training = 15.5 +/- 3.5 years) (Control n = 8; IdFAI = 7.13 +/- 3.40 points; age = 19 +/- 0.6 years; training = 15.9 +/- 2.5 years). Strength and leap landing mechanics were measured on the affected ankle for the CAI group and on the preferred landing leg of a leap for the control group. Concentric and eccentric ankle plantar flexion, and subtalar inversion and eversion strength were determined with dynamometry set at an angular velocity of 60 degrees center dot s(-1). Force plates and motion capture cameras were used to calculate lower extremity kinematic and kinetic data as participants performed 3 saut de chat leaps. Independent t-tests were calculated to determine differences between groups. Results: Compared to dancers without CAI, dancers with CAI had lower eccentric plantar flexor strength, landed with higher vertical ground reaction forces, and absorbed greater power at the knee-joint during landing. Conclusion: Whether dancers who are weaker are more prone to injury or ankle-joint injury leads to muscular weakness is unknown. Dancers with CAI appear to lack control during leap landing while concomitantly shifting loads proximally away from the ankle-joint. We encourage dancers with and without CAI to engage in additional training that enhances ankle strength.