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ANKLE KINEMATICS IN NEW AND OLD CHEERLEADER FOOTWEAR DURING AN INVERSION ANKLE SPRAIN PERTURBATION

Abstract

Samuel J. Wilson1, Abigail Johnson2, Jessica Mutchler1, Diego Castro-Diaz1, Li Li, FACSM1, Barry Munkasy1. 1Georgia Southern University, Statesboro, GA. 2University of Florida, Gainesville, FL.

BACKGROUND: Cheerleading requires athletes to perform sports-specific movements such as tumbling, jumping, and stunting. The leading injury in cheerleading is an inversion ankle sprain. Previous research has examined biomechanics of the ankle during a step-down task on flat and tilted surfaces and suggests that footwear may influence recovery mechanisms during an inversion perturbation. However, cheerleading-specific footwear has not been examined. Thus, the purpose of this study was to examine ankle kinematics in collegiate cheerleaders while wearing “old” and “new” cheer shoes during a step-down landing task. METHODS: Twenty-five healthy male (n = 5) and female (n = 20) collegiate cheerleaders with no history of neuro-musculoskeletal disorders completed this study. Participants completed unexpected step-down tasks on a flat surface and a surface tilted 25 degrees in the frontal plane from a height of 30cm. Initial contact was identified from the force plate and max inversion ankle angle and maximum inversion velocity during the 150-ms post initial contact. A 2 x 2 (footwear [Old vs New] x condition [level vs tilted]) repeated measures analysis of variance was used to analyze time-averaged ankle movement with an alpha level of 0.05 and partial eta squared was calculated for measures of effect size. RESULTS: Analyses revealed a statistically significant interaction between shoe and condition when examining the ankle joint angle during step-down tasks (F(1,24)=12.070, p = 0.002). Further investigation revealed main effects of both shoe (F(1,24)=85.541, p < 0.001) and condition (F(1,24)=893.489, p < 0.001) when examining ankle joint angular velocity during step-down tasks. CONCLUSIONS: Old shoes and tilted surfaces appear to display decrements in step-down, landing mechanics when compared to their counterparts. Previous research has suggested footwear differences in step-down landing mechanics. The older cheer footwear may have worn down soles and shoe body through continued use. The decreased structural support of the footwear may explain the increases in inversion ankle angle and velocity during landing. These findings may suggest that regularly replacing aging cheer footwear is important in reducing injury risk.

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