Background An ACL tear is one of the most serious injuries in sports, especially for females. A clinically based ACL injury prediction algorithm is thought to identify female athletes with high Knee Abduction Moment and has gained popularity. The hip abductors are considered as one of most important muscle groups to control knee position.

Objective To investigate the effectiveness of eccentric hip abduction exercise on Knee Abduction Moment.

Design Intervention, one-year follow-up.

Setting University Division 1 (cheerleading), Clinical setting

Participants 18 knees of 9 female freshman (18 yrs old).

Intervention We used an eccentric hip abduction exercise. To start the athletes lay on contralateral side, lifting the upper leg to the end of hip abduction range of motion. Then, the partner pushed the leg downwards until the foot hit the other foot laying ob the ground while the athlete resisted. The athletes implemented one set of 10 repetitions each training session as part of the warm-up routine.

Main Outcome Measurements The probability of High Knee Load was calculated by scoring points of tibia length, knee valgus motion, knee flexion ROM, body mass, and quadriceps:hamstrings torque ratio. Knee Abduction Moment was measured at baseline and one year after starting training. We defined a 75% or higher probability of high knee load as being at a high risk.

Results At baseline, when the 9 athletes entered university as freshmen, there 3 out of 18 knees were scored as being at high risk, compared to 1 knee one year after implementing the eccentric knee abduction exercise.

Conclusions Implementing an eccentric hip abduction exercise as part of routine warm-up has the potential to decrease the number of knees with high knee load among collegiate cheerleaders.