This group was recruited to conduct auto-regulated blood flow restriction exercise for 30-min, three times a week for six weeks by a trained physiotherapist.

This group was recruited to conduct non-regulated blood flow restriction exercise for 30-min, three times a week for six weeks by a trained physiotherapist.

The control group was recruited to conduct no blood flow restriction exercise (Cuff with 0 pressure) 30-min, three times a week for 6 weeks.

This group was recruited to conduct auto-regulated blood flow restriction exercise for 30-min, three times a week for six weeks by a trained physiotherapist, the subjects were asked to perform the following exercises: standing single leg calf raises with lateral resistance using a band, seated soleus raise, single leg balance on the edge of a step clearing the front foot with band on the big toe. SmartCuff 3.0 BFRT tool was used to automatically determine the individualized 50% arterial blood occlusion pressure for the BFRT group at the femoral artery, the cuff was connected to the smart tool device for the auto-regulated group to regulate the cuff pressure during muscle contraction and relaxation. The cuff was deflated in between exercises.

An isokinetic dynamometer (Physiomed Elektromedizin AG [TP Module, CON-TREX MJ], Schnaittach, Germany) was used for strength testing. Using the previously identified ankle evertors/invertors and plantarflexors/dorsiflexors muscles, the investigators assessed the average peak torque to body weight ratio (concentric/concentric) at an angular velocity of 60°/s. Calibration of the dynamometer was performed prior to evaluation. Submaximal three and maximal three exercise sessions were given to participants to acclimate them to the testing methodology. Each subject rested for two minutes before cycling through the active range of motion three times in a row at maximum concentric contraction. To provide sufficient recovery between contractions, a 5-minute rest interval was included in each test condition. It was expected that participants would give it their all when taking the exam. For every test, the appropriate ankle isokinetic device was used for strength testing.

For the purpose of clinical treatment and research investigations involving young people with chronic ankle instability, the foot and ankle disability index (FADI) self-report measure was advocated. Results showed that it was responsive, reliable, and valid for patients with chronic ankle instability. There are a total of 26 items: 22 that pertain to activities and 4 that are associated with pain. The activity item is assessed on a scale from 0 (very difficult) to 4 (very easy), whereas the FADI 4 pain items are graded from 0 (very terrible pain) to 4 (very little pain) (Hale and Hertel, 2005). The overall value of the FADI is 104 points. A score of 100% on the FADI indicated that there was no abnormality.