Effects of balance training on postural control, gait, and function in those with chronic ankle instability

Ankle sprains are one of the most common injuries in the physically active population. Recurrent ankle sprains and the consequent feeling of the ankle "giving way" is known as chronic ankle instability (CAI). There have been several contributing factors associated with CAI including altered postural control and gait mechanics. Balance training has been purported to improve functional outcomes in those with CAI, however there is limited evidence regarding the mechanisms of improvement. The purposes of the dissertation were to investigate the effect of a 4 week progressive balance training program among individuals with CAI on: 1) self-reported function as measured by the FADI and FADI Sport instruments, 2) measures of mechanical instability with an instrumented arthrometer, 3) static and dynamic postural control as assessed by traditional and time-to-boundary (TTB) measures of center of pressure (COP) excursions and the Star Excursion Balance Test (SEBT), and 4) walking and jogging gait parameters. Thirty-one participants with self-reported chronic ankle instability were randomly assigned to a balance training group or a control group. All subjects completed two testing sessions in which self-reported functional status, static postural and dynamic postural control, mechanical instability of the lateral ligaments of the ankle, and walking and jogging gait were evaluated. Study 1 examined the effects of balance training on self-reported function and static and dynamic postural control. Study 2 examined the effects of balance training on measures of mechanical instability and ankle kinematics during walking and jogging. In study 1, significant improvements were found in self-reported function in those who underwent balance training compared to their pretest measures and those who did not. The balance training group also demonstrated significant improvements the magnitude and variability of TTB measures compared to pretest and the posttest of the control group. This indicated that the balance training group had significantly more time to make postural corrections to maintain single limb stance. The traditional COP-based measures did not consistently detect significant differences between tests or groups. The balance training group also significantly improved in the SEBT reach distance compared to pretest and the posttest measures of the control group. These findings indicated that balance training significantly improved self-reported function and postural control in those with CAI. In Study 2, the balance training group had significant changes in inversion/eversion and shank rotation kinematics and the coupling between the rearfoot and shank in walking and jogging. The balance training group demonstrated significantly less variability in the coupling of the rearfoot and shank after rehabilitation, indicating a more stable relationship between the two segments during walking but not jogging. There were no concurrent changes in the mechanical properties of the lateral ligaments of the ankle. This suggests that the changes in the kinematics and coupling measures in those who underwent balance training were a result of alterations in sensorimotor control of the rearfoot and shank. In conclusion, this randomized controlled trial revealed that individuals with CAI who completed a supervised 4 week dynamic balance training program had significant improvements in self-reported function, static and dynamic postural control, and gait kinematics. Note: Abstract extracted from PDF file via OCR.