***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Background Female athletes have a higher risk of anterior cruciate ligament injury than their male counterparts who play at similar levels in sports involving pivoting and l and ing . Hypothesis The competitive female basketball players who participated in a sports injury prevention training program  would show better muscle strength and flexibility and improved biomechanical properties associated with anterior cruciate ligament injury than during the pretraining period and than posttraining parameters in a control group . Study Design Controlled laboratory study . Methods A total of 22 high school female basketball players were recruited and r and omly divided into 2 groups ( the experimental group and the control group , 11 participants each ) . The experimental group was instructed in the 6 parts of the sports injury prevention training program and performed it during the first 20 minutes of team practice for the next 8 weeks , while the control group performed their regular training program . Both groups were tested with a rebound-jump task before and after the 8-week period . A total of 21 reflective markers were placed in preassigned positions . In this controlled laboratory study , a 2-way analysis of variance ( 2 × 2 ) experimental design was used for the statistical analysis ( P < .05 ) using the experimental group and a testing session as within and between factors , respectively . Post hoc tests with Sidak correction were used when significant factor effects and /or interactions were observed . Results A comparison of the experimental group 's pretraining and posttraining results identified training effects on all strength parameters ( P = .004 to .043 ) and on knee flexion , which reflects increased flexibility ( P = .022 ) . The experimental group showed higher knee flexion angles ( P = .024 ) , greater interknee distances ( P = .004 ) , lower hamstring-quadriceps ratios ( P = .023 ) , and lower maximum knee extension torques ( P = .043 ) after training . In the control group , no statistical differences were observed between pretraining and posttraining findings ( P = .084 to .873 ) . At pretraining , no significant differences were observed between the 2 groups for any parameter ( P = .067 to .784 ) . However , a comparison of the 2 groups after training revealed that the experimental group had significantly higher knee flexion angles ( P = .023 ) , greater knee distances ( P = .005 ) , lower hamstring-quadriceps ratios ( P = .021 ) , lower maximum knee extension torques ( P = .124 ) , and higher maximum knee abduction torques ( P = .043 ) than the control group . Conclusion The sports injury prevention training program improved the strength and flexibility of the competitive female basketball players tested and biomechanical properties associated with anterior cruciate ligament injury as compared with pretraining parameters and with posttraining parameters in the control group . Clinical Relevance This injury prevention program could potentially modify the flexibility , strength , and biomechanical properties associated with ACL injury and lower the athlete 's risk for injury Objective To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury  in adolescent female football players . Design Stratified cluster r and omised controlled trial with clubs as the unit of r and omisation . Setting 230 Swedish football clubs ( 121 in the intervention group , 109 in the control group ) were followed for one season ( 2009 , seven months ) . Participants 4564 players aged 12 - 17 years ( 2479 in the intervention group , 2085 in the control group ) completed the study . Intervention 15 minute neuromuscular warm-up programme ( targeting core stability , balance , and proper knee alignment ) to be carried out twice a week throughout the season . Main outcome measures The primary outcome was rate of anterior cruciate ligament injury ; secondary outcomes were rates of severe knee injury ( > 4 weeks ’ absence ) and any acute knee injury . Results Seven players ( 0.28 % ) in the intervention group , and 14 ( 0.67 % ) in the control group had an anterior cruciate ligament injury . By Cox regression analysis according to intention to treat , a 64 % reduction in the rate of anterior cruciate ligament injury was seen in the intervention group ( rate ratio 0.36 , 95 % confidence interval 0.15 to 0.85 ) . The absolute rate difference was −0.07 ( 95 % confidence interval −0.13 to 0.001 ) per 1000 playing hours in favour of the intervention group . No significant rate reductions were seen for secondary outcomes . Conclusions A neuromuscular warm-up programme significantly reduced the rate of anterior cruciate ligament injury in adolescent female football players . However , the absolute rate difference did not reach statistical significance , possibly owing to the small number of events . Trial registration Clinical trials NCT00894595 Previous research suggests high impact forces generated during l and ings contribute to noncontact anterior cruciate ligament ( ACL ) injuries . In women , neuromuscular differences appear to modify the ability to dissipate l and ing forces when compared to men . This study examined peak vertical impact forces ( Fp ) and rate of force development ( RFD ) following a 9-week , low-intensity ( simple jump-l and ing-jump tasks ) and volume ( number of foot contacts per workout ) plyometric-based knee ligament injury prevention ( KLIP ) program . Female subjects were r and omly assigned into control ( n = 14 ) and treatment ( n = 14 ) groups . Treatment subjects attended KLIP sessions twice a week for 9 weeks , and control subjects received no intervention .  Ground reaction forces ( Fp and RFD ) generated during a step-l and protocol were assessed at study onset and termination . Significant reductions in Fp ( p = 0.0004 ) and RFD ( p = 0.0205 ) were observed in the treatment group . Our results indicate that 9 weeks of KLIP training altered l and ing strategies in women to lower Fp and RFD . These changes are considered conducive to a reduced risk of knee injury while l and ing Background Anterior cruciate ligament ( ACL ) injury prevention programs show promising results with changing movement ; however , little information exists regarding whether a program design ed for an individual 's movements may be effective or how baseline movements may affect outcomes . Hypothesis A program design ed to change specific movements would be more effective than a “ one-size-fits-all ” program . Greatest improvement would be observed among individuals with the most baseline error . Subjects of different ages and sexes respond similarly . Study Design R and omized controlled trial ; Level of evidence , 1 . Methods One hundred seventy-three youth soccer players from 27 teams were r and omly assigned to a generalized or stratified program . Subjects were videotaped during jump-l and ing trials before and after the program and were assessed using the  L and ing Error Scoring System ( LESS ) , which is a valid clinical movement analysis tool . A high LESS score indicates more errors . Generalized players performed the same exercises , while the stratified players performed exercises to correct their initial movement errors . Change scores were compared between groups of varying baseline errors , ages , sexes , and programs . Results Subjects with the highest baseline LESS score improved the most ( 95 % CI , −3.4 to −2.0 ) . High school subjects ( 95 % CI , −1.7 to −0.98 ) improved their technique more than pre – high school subjects ( 95 % CI , −1.0 to −0.4 ) . There was no difference between the programs or sexes . Conclusions Players with the greatest amount of movement errors experienced the most improvement . A program 's effectiveness may be enhanced if this population is targeted To prospect ively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes , we monitored two groups of female athletes , one trained before sports participation and the other not trained , and a group of untrained male athletes throughout the high school soccer , volleyball , and basketball seasons . Weekly reports included the number of practice and competition exposures and mechanism of injury . There were 14 serious knee injuries in the 1263 athletes tracked through the study . Ten of 463 untrained female athletes sustained serious knee injuries ( 8 noncontact ) , 2 of 366 trained female athletes sustained serious knee injuries ( 0 noncontact ) , and 2 of 434 male athletes sustained serious knee injuries ( 1 noncontact ) . The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes , 0.12 in trained female athletes , and 0.09 in male athletes ( P 0.02 , chi-square analysis ) . Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes ( P 0.05 ) and 4.8 times higher than male athletes ( P 0.03 ) . The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes ( P 0.86 ) . The difference in the incidence of noncontact injuries between the female groups was also significant ( P 0.01 ) . This prospect i ve study demonstrated a decreased incidence of knee injury  in female athletes after a specific plyometric training program Abstract Objective To investigate the effect of a structured warm-up programme design ed to reduce the incidence of knee and ankle injuries in young people participating in sports . Design Cluster r and omised controlled trial with clubs as the unit of r and omisation . Setting 120 team h and ball clubs from central and eastern Norway ( 61 clubs in the intervention group , 59 in the control group ) followed for one league season ( eight months ) . Participants 1837 players aged 15 - 17 years ; 958 players ( 808 female and 150 male ) in the intervention group ; 879 players ( 778 female and 101 male ) in the control group . Intervention A structured warm-up programme to improve running , cutting , and l and ing technique as well as neuromuscular control , balance , and strength . Main outcome measure The rate of acute injuries to the knee or ankle . Results During the season , 129 acute knee or ankle injuries occurred , 81 injuries in the control group ( 0.9 ( SE 0.09 ) injuries per 1000 player hours ; 0.3 ( SE 0.17 ) in training v 5.3 ( SE 0.06 ) during matches ) and 48 injuries in the intervention group ( 0.5 ( SE 0.11 ) injuries per 1000 player hours ; 0.2 ( SE 0.18 ) in training v 2.5 ( SE 0.06 ) during matches ) . Fewer injured players were in the intervention group than in the control group ( 46 ( 4.8 % ) v ( 76 ( 8.6 % ) ; relative risk intervention group v control group 0.53 , 95 % confidence interval 0.35 to 0.81 ) . Conclusion A structured programme of warm-up exercises can prevent knee and ankle injuries in young people playing sports . Preventive training should therefore be introduced as an integral part of youth sports programmes Objective Introduction of a neuromuscular training program will increase muscle strength , balance , and proprioception in elite female h and ball players . Design Prospect i ve intervention study . Participants Thirty-five female team h and ball players from 2 teams in the elite division participated . Their mean age was 23 ( ±2.5 ) years , and their mean weight was 69.2 ( ±7.3 ) kg . They had played h and ball for 14.9 ( ±3.2 ) years , 4.7 ( ±2.8 ) years at the top level . The total number of training hours per week was 10 to 11 . InterventionBased on earlier studies and knowledge about common risk situations in team h and ball , an anterior cruciate ligament ( ACL ) injury prevention program with 3 different sets of exercises was developed , each set with a 5-step progression from simple to more challenging exercises . The teams were instructed to use the program a minimum of 3 times a week during a training period of 5 to 7 weeks , and then once a week during the season . The duration of each training session was approximately 15 minutes . Main outcome measures Balance ( KAT 2000 ) , proprioception ( threshold to detection of passive motion ) , muscle strength ( Cybex 6000 ) , and 3 functional knee tests . The players were tested pretraining ( test 1 ) and 8 weeks ( test 2 ) and 12 months ( test 3 ) after the training started . Results There was a significant improvement in dynamic balance between test 1 and test 2 , with a balance index ( BI ) of 924 ( ±225 ) and 778 ( ±174 ) , respectively ( P = 0.01 ) . The effect on dynamic balance was maintained 1 year after training ( BI , 730 ± 156 ) . For static balance , no statistically significant changes were found . For the other variables measured , there were no statistical differences during the study period . Conclusion The ACL injury prevention training program improved dynamic balance in an elite team h and ball players A set of exercises -- the " 11"--have been selected to prevent football injuries . The purpose of this cluster-r and omized controlled trial was to investigate the effect of the " 11 " on injury risk in female youth football . Teams were r and omized to an  intervention ( n=59 teams , 1091 players ) or a control group ( n=54 teams , 1001 players ) . The intervention group was taught the " 11 , " exercises for core stability , lower extremity strength , neuromuscular control and agility , to be used as a 15-min warm-up program for football training over an 8-month season . A total of 396 players ( 20 % ) sustained 483 injuries . No difference was observed in the overall injury rate between the intervention ( 3.6 injuries/1000 h , confidence interval ( CI ) 3.2 - 4.1 ) and control group ( 3.7 , CI 3.2 - 4.1 ; RR=1.0 , CI 0.8 - 1.2 ; P 
    Output:
    
Three ACL intervention programs successfully reduced noncontact ACL injury incidence rates in female adolescent athletes .