Muscle Strength and Flexibility Differences Between High and Low Landing Error Scores in Youth Female Athlete

Background: As the number of female athletes participating in sports increases, so does the injury rate for female athletes, especially ACL injuries. Several risk factors for ACL injuries have been proposed, including anatomical, neuromuscular, and muscle strength elements. Weak gluteus muscle strength, decreased trunk proprioception and trunk control, and small range of motion (ROM) are especially indicated as ACL injury risk factors. The Landing Error Scoring System (LESS) is a clinical assessment tool used to identify subjects who have a higher risk of sustaining a future ACL injury. The purpose of this study was to examine the difference in lower extremity muscle strength and ROM between those female athletes with a higher LESS score and those with a lower LESS score.;Methods: Sixty-four female participants performed a jump-landing task that was recorded by video cameras from the frontal plane. The researcher assessed each participant's landing mechanics using the LESS. Quadriceps and gluteus muscle strength was determined using Biodex and a handheld dynamometer, respectively. External and internal hip ROM (ER ROM and IR ROM, respectively) were measured using a dynamometer. Independent t-tests were used to analyze the differences between error scores during the jump-landing task and muscle strength as well as hip ROM measurements.;Results: No significant differences were found between high and low LESS score groups. However, the participants who displayed knee displacement errors at the maximum knee flexion position had significantly decreased ER ROM of the non-dominant hip (p = 0.011) as well as greater non-dominant hip ROM difference (p = 0.021), indicating greater femoral anteversion. Participants who displayed knee displacement errors at initial contact also showed greater asymmetry in abduction (p = 0.009).;Conclusions: Although there were no significant differences between participants with a high and low LESS score, the female athletes with knee displacement errors during the jump-landing task had weaker muscle strength and decreased hip ER ROM. The results from this study could be used to develop more effective lower extremity injury prevention rehabilitation exercise programs for young female athletes.