Background: Functional ankle instability (FAI) indicating a decrease in muscle strength, proprioception, neuromuscular control, balance and postural control function.
Objective: To investigate the effect of jumping exercise on the supporting surface on the ankle muscle thickness, proprioceptive sensation, and balance in adults with FAI.
Design: Randomized Controlled Trial.
Methods: Twenty young people with FAI were randomly assigned to the unstable supporting surface jump group (N=10) and the stable supporting surface jump group (N=10). The intervention was conducted three times a week for eight weeks, and for 30 minutes per session. Trampoline was used as an unstable support surface and the stable support surface was carried out on a regular floor. The thickness of the tibialis anterior muscle and medial gastrocnemius muscle was measured by ultrasonography, and the proprioception of dorsiflexion and plantarflexion was measured using an electrogoniometer. The dynamic balance was also measured with a balance meter.
Results: The the muscle thickness of the medial gastrocnemius muscle was significantly higher in the stable supporting surface jump group than in the unstable supporting surface jump group (p<.05). Furthermore, the plantar flexion proprioception and dynamic balance were significantly improved in the unstable supporting surface jump group than in the stable supporting surface jump group in the intergroup comparison (p<.05).
Conclusions: The conclusion has been reached in this study that the jumping exercise on the unstable supporting surface could be a more effective in improving FAI than the regular surface.

INTRODUCTION
 METHODS
 RESULTS
 DISCUSSION
 CONCLUSION
 REFERENCES

• Byeonggeun Kim(Nambu University) Correspondence
• Chibok Park(Nambu University)