Effect of the 11+ on Biomechanical Profile Related to ACL Injury Risk in Elite Male Youth Soccer Players

Oral Presentation
Paper ID : 1506-12THCONG
Oral / Poster Presentation File: 1506-12THCONG.mp4 
1Department of Sport Sciences, Faculty of Literature and Humanities, University of Zabol, Zabol, Iran
2Department of Corrective Exercises and Sports Injuries, Faculty of Sport Science, Shahid Bahonar University of Kerman, Kerman, Iran
3Department of Sport Biomechanics, Faculty of Sport Science, Shahid Bahonar University of Kerman, Kerman, Iran
4Department of Health and Sport Management, School of Health and Sport Sciences, Osaka University of Health and Sport Sciences, Osaka, Japan
5Department of Epidemiology and Biostatistics, Faculty of Health, Birjand University of Medical Sciences, Birjand, Iran
Few studies exist regarding the evaluating progress of interventions based on initial biomechanical profile related to ACL injury risk. The purpose of this study was to determine the differential effects of
warm-up programs on landing techniques based on their pre-training LESS scores.
Twenty-four elite male youth soccer players participated in this study. The intervention group performed the 11+ program for 8 weeks, whereas the control group just performed their regular warm-up program. Before and after intervention all participants were assessed for landing mechanics utilizing landing error scoring system (LESS). To assess the ability of warm-up programs to predict posttraining LESS scores when the effects of pretraining LESS scores are controlled for, a standard multiple regression model was performed. Furthermore, two McNemar tests were employed for comparing the proportion of people who are classified as high and low-risk prior to, and following the warm-up programs. Significance was ac‌cepted at the 95% confidence level for all statistical parameters (p<0.05).
Standard multiple regression results showed 71% of the posttraining LESS scores was explained by knowing the pretraining LESS scores and the intervention group, F(2,23), 25.63, p < 0.001, with R2 = .709. Type of warm-up program explained 66.4% of the variance in posttraining LESS scores, after controlling for the influence of pretraining LESS scores and the mean of the posttraining LESS scores in the 11+ group had a statistically significant reduction after performing the program.
The results of McNemar tests indicated that there was a significant change in the proportion of participants determined as at risk for ACL injury following the 11+ program when compared with prior to the program (p=.031) so that after performing the 11+, participants with the higher risk profile acquire greater improvement from the 11+ program. Also, the results did not indicate any significant difference in the proportion of risk category following the routine warm-up program (p>0.05).
The present study provides evidence that soccer players with a higher risk profile would acquire greater benefits from 11+ warm-up program than regular one and that targeting them may improve the efficacy of the 11+ program.