Chronic Ankle Instability and Aging: Combined Effects on Physical Function, Joint Health, and Daily Activity - Project Summary/Abstract Chronic ankle instability (CAI) is a common disorder that can lead to reduced physical function, joint health, and physical activity. Similar to healthy aging populations, balance and ankle joint health of individuals with CAI decline from young adulthood to middle adulthood. Age-related changes in balance, walking ability, reaction time, and strength can both contribute to and result from reduced physical activity. Impairments in function and declining physical activity are known to increase the likelihood of developing comorbidities and elevate risk of all-cause mortality in older adults. Older adults with CAI have reduced balance performance compared to healthy individuals of the same age, indicating that declines in the CAI population are more pronounced. With respect to ankle joint health, talar cartilage thickness is reduced in approximately 80% of individuals who have CAI for at least 10 years. However, whether CAI-related declines from young through older adulthood are steeper than healthy aging adults is unknown. No studies have examined the effects of CAI on physical activity or ankle joint health in populations aged beyond early adulthood through middle and older ages. Also, no CAI research has tracked physical activity, ankle joint health, or physical function longitudinally to examine declines over time. The purpose of this proposed study is to determine the extent to which CAI and aging independently and interactively affect joint health, physical activity, balance, gait, reaction time, muscular strength, and perceived function. To accomplish this objective, we will use a longitudinal study design in which 180 participants will be equally divided across two independent variables: age (20-39, 40-59, and 60-79 years) and injury history (CAI & control [CON]). The CON group will be matched to the CAI group based on sex and age. After enrollment, participants will undergo three separate laboratory testing sessions: Time Point 1 (baseline) Time Point 2 (4 weeks after Time Point 1), and Time Point 3 (12 months after Time Point 1). In each laboratory session, participants will undergo tests of ankle joint health, balance, gait, reaction time, strength, and perceived function. Each laboratory testing session will be followed by 7 days of physical activity tracking using a wearable monitor. To analyze the effects of CAI and aging cross-sectionally and longitudinally, we will employ a combination of Generalized Linear Model (GLM) and Analysis of Variance (ANOVA) models that as our primary statistical analyses. Each model will control for potentially relevant covariates such as injury and disease comorbidities. When appropriate, Tukey post hoc analyses will be performed, and effect sizes will be calculated. We expect that CAI and higher age will lead to worse performance cross-sectionally and greater declines longitudinally on measures of joint health, physical activity, balance, gait, reaction time, strength, and perceived function versus those without CAI and/or of lower age.
