Background: In Taekwondo athletes, ankle sprain is the most common risk factor for injury. Repeated ankle injuries lead to weakness and imbalance of the ankle muscles, resulting in chronic ankle instability (CAI). Both the ankle and toe muscles contribute to the inversion and eversion of the foot at the subtalar joint. Therefore, it is necessary to consider the ankle and toe joint positions when measuring ankle invertor and evertor strength. Objects: This study aimed to compare the muscle strength and ratio differences of the ankle invertor and evertor muscles in both the toe and ankle positions between the CAI and uninjured sides in Taekwondo athletes. Methods: Fifteen Taekwondo athletes participated in this study. The isometric strengths of both the ankle invertor and evertor were determined in different ankle and toe positions (dorsiflexion with toe extension, dorsiflexion with toe flexion, plantarflexion with toe extension, and plantarflexion with toe flexion). Paired t-tests were used to determine the differences between the ankle invertor and evertor in strength and ratio according to toe and ankle positions between the ankle CAI side and the uninjured side. Results: The results demonstrated that ankle evertor strength significantly decreased in all ankle and toe positions on the CAI side (p < 0.05). In addition, significant differences were observed in the ratios of the ankle invertor and evertor strengths in the dorsiflexion with toe flexion, plantarflexion with toe extension, and plantarflexion with toe flexion positions (p < 0.05). Conclusion: The findings of this study suggest that athletes, trainers, and clinicians should consider ankle and toe positions when measuring invertor and evertor strength and develop ankle rehabilitation protocols for Taekwondo athletes with CAI.

INTRODUCTION
MATERIALS AND METHODS
    1. Participants
    2. Instrumentation
    3. Procedure
    4. Data Analysis
    5. Statistical Analysis
RESULTS
DISCUSSION
CONCLUSIONS
FUNDING
ACKNOWLEDGEMENTS
CONFLICTS OF INTEREST
AUTHOR CONTRIBUTION
ORCID
REFERENCES

• Beom-jun Kim(Department of Physical Therapy, The Graduate School, Yonsei University, Kinetic Ergocise Based on Movement Analysis Laboratory)
• Ui-jae Hwang(Kinetic Ergocise Based on Movement Analysis Laboratory)
• Oh-yun Kwon(Kinetic Ergocise Based on Movement Analysis Laboratory, Department of Physical Therapy, College of Software and Digital Healthcare Convergence, Yonsei University, Wonju, Korea) Corresponding author