Chronic Ankle Instability and Neuromuscular Performance in Prerecruitment Infantry Soldiers

Context: Ankle instability can describe various impairments, including perceived instability (PI), mechanical instability (MI), and recurrent sprains (RSs), alone or combined. Objective: To examine the prevalence of 8 ankle impairment subgroups and their effect on neuromuscular performance in prerecruitment combat soldiers. Design: Cross-sectional study. Setting: Military infantry basic training base. Patients or Other Participants: A total of 364 infantry male combat soldiers entering basic training (aged 18–21 years). Main Outcome Measure(s): Participants were assessed for PI (via the Cumberland Ankle Instability Tool), MI (using the Anterior Drawer Test and Medial Talar Tilt Test), and RSs (based on history) of their dominant and nondominant legs. Injuries were categorized in 8 subgroups: PI, RSs, PI þ RSs, MI, PI þ MI, MI þ RSs, PI þ MI þ RSs, and none. Participants were screened for neuromuscular performance (dynamic postural balance, proprioceptive ability, hopping agility, and triceps surae muscle strength) during the first week of military basic training. Results: For the dominant and nondominant legs, RSs were reported by 18.4% (n ¼ 67) and 20.3% (n ¼ 74) of the participants, respectively; PI was reported by 27.1% (n ¼ 99) and 28.5% (n ¼ 104) of the participants, respectively; and MI was seen in 9.9% (n ¼ 36) and 8.5% (n ¼ 31) of the participants, respectively. A 1-way analysis of variance showed differences in the mean proprioceptive ability scores (assessed using the Active Movement Extent Discrimination Apparatus) of all subgroups with impairments in both the dominant and nondominant legs (F ¼ 6.943, h² ¼ 0.081, P, .001 and F ¼ 7.871, h² ¼ 0.091, P, .001, respectively). Finally, differences were found in the mean muscle strength of subgroups with impairment in the nondominant leg (F ¼ 4.884, h² ¼ 0.056, P ¼ .001). Conclusions: A high prevalence of ankle impairments was identified among participants who exhibited reduced abilities in most neuromuscular assessments compared with those who did not have impairments. Moreover, participants with 1 impairment (PI, MI, or RSs) exhibited different neuromuscular performance deficits than those with .1 impairment.