Context: Patients with chronic ankle instability (CAI) have demonstrated sensorimotor impairments. Submaximal force steadiness and accuracy measure sensory, motor, and visual function via a feedback mechanism, which helps researchers and clinicians to comprehend sensorimotor deficits associated with CAI. Objective: To determine if participants with chronic ankle instability experience deficits in hip and ankle submaximal force steadiness and accuracy compared to healthy controls. Design: A case-controlled study Setting: Research Laboratory Patients and Other Participants: Twenty-one CAI patients and 21 uninjured controls participated in this study. Intervention(s): n/a. Main Outcome Measure(s): Maximal voluntary isometric contraction (MVIC), force steadiness and accuracy (10% and 30% of their MVIC) of ankle evertors, invertors, and hip abductors. The central 10-sec (20–87% of the total time) of the 3 trials were analyzed. An independent t-test was used to assess MVIC. Two-way, 2 × 3, ANOVAs were used to assess force steadiness and accuracy. Results: Relative to controls, the CAI group demonstrated lower accuracy in invertors (p =.0006). Across all motions, the CAI group showed less steadiness (p = .0005) and lower accuracy (p = .0074) than the controls in 10% MVIC. In terms of MVIC, the CAI group showed less force output in hip abduction compared with the control group (p < .0001). Conclusions: CAI patients showed an inability to control ongoing fine force (10% and 30% of their MVIC) through a feedback mechanism during an active test. These findings suggest deficits in sensorimotor control that lead CAI patients to be more susceptible to injury positions since they have difficulty integrating the peripheral information and correcting their movement in relation to visual information.

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Little is known about how disrupted vision affects visual reliance during postural control. postural control. Twenty-four physically active adults volunteered to participate in the study. Static postural control was quantified with center of pressure measures during a one-legged balance test with four different visual inputs (eyes-open (EO), high frequency of strobe vision (HSV), low frequency of strobe vision (LSV), and eyes-closed (EC)) and on two different surfaces (firm and foam). Dynamic postural control was calculated by the dynamic postural stability index and the Y-Balance test for three different visual inputs (EO, HSV, and LSV) and the two different surfaces. Romberg ratios (HSV/EO, LSV/EO, and EC/EO) were then calculated and used for statistical analysis to assess visual contribution during postural control. In the results, Romberg ratios were higher when people were on the foam surface than the firm surface in center of pressure total path in medial-lateral and anterior-posterior directions (p < 0.05, both directions). Similarly, Romberg ratios were higher on the foam surface than the firm surface in dynamic stability index in medial-lateral and anterior-posterior directions (p < 0.05, both directions). Stroboscopic glasses could alter visual reliance when the somatosensory system is disturbed by a foam pad during both static and dynamic postural control. Clinicians could use the glasses to manipulate visual reliance during dynamic balance training for patients with musculoskeletal injuries.

Individuals with chronic ankle instability (CAI) are believed to rely more on visual information during postural control due to impaired proprioceptive function, which may increase the risk of injury when their vision is limited during sports activities. Objectives: To compare (1) the effects of balance training with and without stroboscopic glasses on postural control and (2) the effects of the training on visual reliance in patients with CAI. Design: A randomized controlled clinical trial. Methods: Twenty-eight CAI patients were equally assigned to one of 2 groups: strobe or control group. The strobe group wore stroboscopic glasses during a 4week balance training. Static postural control, a single-leg hop balance test calculated by Dynamic Postural Stability Index (DPSI), and the Y-Balance test (YBT) were measured. During the tests, there were different visual conditions: eyesopen (EO), eyes-closed (EC), and strobe vision (SV). Romberg ratios were then calculated as SV/EO, and EC/EO and used for statistical analysis.Results: The strobe group showed a higher pretest-posttest difference in velocity in the medial-lateral direction and vertical stability index under SV compared with the control group (p < .05). The strobe group showed higher differences in EC/EO for velocity in the medial-lateral and anterior-posterior directions, and 95% confidence ellipse area (p < .05), and in SV/EO for velocity in the mediallateral, 95% confidence ellipse area, and YBT-anterior direction (p < .05). Conclusion:The 4-week balance training with stroboscopic glasses appeared to be effective in improving postural control and altering visual reliance in patients with CAI.