Decreased ankle and hip isometric peak torque in young and middle-aged adults with chronic ankle instability

Objectives: To compare ankle, knee and hip isometric peak torque between young and middle-aged adults with CAI, copers and un-injured controls. Design: Cross-sectional. Setting: Research Laboratory. Participants: One hundred fifty-six young and middle-aged adults with or without CAI volunteered. Main outcome measures: A handheld dynamometer measured isometric dorsiflexion, plantarflexion, knee extension, hip extension and hip abduction peak force during a 5 s trial. Average peak torque was calculated and normalized to body mass. Results: A significant Age by Injury interaction for dorsiflexion suggest middle-aged un-injured controls (p < 0.001) and copers (p < 0.001) had lower isometric peak torque compared to their young adult counterparts, but there were no differences between young and middle-aged adults with CAI (p > 0.05). Significant Injury main effects suggest the CAI group had decreased plantarflexion (p = 0.004) and hip extension (p = 0.010) strength compared to un-injured controls, but not copers (p > 0.05). Significant Age main effects for all primary outcome measures were observed, indicating peak torque decreased with age (p < 0.05). Conclusions: Regardless of age, isometric ankle and hip peak torque was lower in participants with CAI compared to un-injured controls, but not copers. These findings provide further evidence towards the impact of CAI in both young and middle-aged adults.