Introduction:The components of the Ground reaction force are of clinical importance. The use of braces can be effective in reducing harmful factors. Therefore, this study aims to investigate the effect of the using air orthoses on the variables of the ground reaction force in people with ankle sprain. Material and methods:10 female with ankle sprain complication participated in this study. Using a force plate (1000 Hz), the components of the Ground reaction force were measured when walking in two conditions with and without braces. Then, the peak variables of the Ground reaction forces, impulse, and loading rate were extracted. The statistical Repeated mesure test with a significance level (P 050.05) was used for statistical analysis. Results: The results showed that there was a significant difference between the two conditions in the synchronized reaction force in the direction of Fx1(p = 0.03), Fx2 (p = 0.008) and Fy1 (p = 0.02), but in the other components there was no difference between the two conditions. Conclusion: The increase in horizontal ground reaction force as a result of the use of air braces indicates greater instability. Also, increasing the posterior reaction force of the ground due to the use of braces is one of the risk factors for knee injury. It seems that the use or non-use of this type of brace depends on future research.
