Context: Few studies have established the prevalence of non-traumatic ankle injuries in ice hockey players. Based on the design of the modern skate boot it may not be obvious; however these injuries are occurring and may possibly be attributed to underlying factors of ankle instability (AI). Objective: The purpose of this research was twofold: (1) to measure ankle strength and stretch reflex response and (2) determine the prevalence of AI, in a group of intercollegiate ice hockey players. Participants: A total of 23 male subjects (age: 20.5+1.0 yr.; height: 178.0+5.6 cm; mass: 85.5+8.1 kg) recruited from a collegiate ice hockey team were screened for AI using the Cumberland Ankle Instability Tool (CAIT). Interventions: Based on CAIT scores (> 27/30 = stable), ankles were sorted into 2 groups, unstable (UA, n=21) or stable (SA, n=25) ankles. With EMG electrodes placed bilaterally on the Tibialis Anterior (TA), Peroneus Longus (PL), and Peroneus Brevis (PB), all subjects were positioned on an ankle perturbation platform. Each subject performed 10 trials per leg, and the stretch reflex response was measured. Subjects also performed strength testing on an isokinetic dynamometer for ankle inversion (INV) and eversion (EV). Both eccentric (ECC) and concentric (CON) muscle actions were assessed at velocities of 30º/sec and 120º/sec. Three maximal test repetitions were recorded for each movement. T-tests were utilized to compare SA to UA for each of these variables. Main Outcome Measures: The ankle inversion perturbation yielded muscle reaction times (RT) and peak EMG values for each trial. All EMG data were normalized to subject MVIC and averaged across trials. Isokinetic peak torque (PT) values were averaged across trials and used to calculate functional ankle strength ratios (EVECC/INVCON). Results: Peak EMG values (%MVIC) per muscle included: TA (SA=62.0+37.8, UA=62.5+47.7); PL (SA=53.7+21.9, UA=59.4+21.2); and PB (SA=81.1+33.5, UA=66.9+32.7). RT (in ms) included: TA (SA=55.7+12.3, UA=60.0+10.4); PL (SA=52.0+12.1, UA=55.2+12.6); and PB (SA=56.9+11.3, UA=59.4+9.5). Average functional strength ratios included: at 30º/sec (SA=1.3+0.3, UA=1.5+0.6) and at 120º/sec (SA=1.4+0.4, UA=1.3+0.2). There were no significant differences between groups for any variable (critical-t<1.407, p>0.05). Conclusions: Interestingly, these male collegiate ice hockey players demonstrate a prevalence of AI based on the CAIT (45.6%); however ankle strength ratios, stretch reflex intensity, and reaction time do not appear to be significantly different between the UA and SA in these athletes. Given the high prevalence of AI in this population, additional research is needed to examine its cause. Keyword(s): medical/medical care, motor skills, safety/injury prevention