Nicole K. Rendos1, Jeffrey D. Simpson2, Hoon Kim3, John R. Harry4. 1Emory University, Atlanta, GA. 2University of West Florida, Pensacola, FL. 3University of North Carolina at Chapel Hill, Chapel Hill, NC. 4Texas Tech University, Lubbock, TX.

BACKGROUND: Single limb hopping tests are used to identify motor-behavioral impairments of the lower limb that are associated with chronic ankle instability (CAI) but are often limited by performance-based metrics. This study compared phase-specific force and time metrics during single limb vertical hopping in participants with and without CAI. METHODS: Twenty-five participants with self-reported CAI (13M, 12F; age: 24±3y; height: 168.3±12.9cm; mass: 72.2±15.2kg) and 25 controls (13M, 12F; age: 25±4y; height: 172.5±6.1cm; mass: 70.8±9.7kg) completed the study. A total of 3 trials consisting of 5 consecutive single limb vertical hops were completed on a force platform. Individuals with CAI performed the hopping task on their affected limb while controls used their preferred limb. Eccentric and concentric phases were identified for each vertical hop from vertical ground reaction force data and the middle 3 hops were analyzed. Peak vertical force, time to peak vertical force, vertical impulse, and phase time were obtained for eccentric and concentric phases and compared between groups with an unpaired t-test (p < 0.05) and Cohen’s D effect sizes (d). RESULTS: Concentric phase time (p=0.041; CAI: 0.23±0.09s vs. Control: 0.19±0.0s; d=0.53) and time to peak concentric vertical force (p=0.020; CAI: 0.08±0.19s vs. Control: 0.03±0.02; d=0.71) were significantly longer in the CAI group with moderate-magnitude differences. While not significant (p=0.066), a moderate-magnitude difference (d=0.45) was observed for concentric vertical impulse between CAI (3.04± 0.56 Ns/kg) and controls (3.40± 0.91 Ns/kg). CONCLUSION: Individuals with CAI demonstrated difficulty transitioning from eccentric to concentric phases, which could reveal a less efficient transfer of lower limb mechanical output from the affected limb during repetitive vertical hopping.

This document is currently not available here.