***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 
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    Input: Background A protective effect on injury risk in youth sports through neuromuscular warm-up training routines has consistently been demonstrated . However , there is a paucity of information regarding the quantity and quality of coach-led injury prevention programmes and its impact on the physical performance of players . Objective The aim of this cluster-r and omised controlled trial was to assess whether different delivery methods of an injury prevention programme ( FIFA 11 + ) to coaches could improve player performance , and to examine the effect of player adherence on performance and injury risk . Method During the 2011 football season ( May – August ) , coaches of 31 tiers 1–3 level teams were introduced to the 11 + through either an unsupervised website or a coach-focused workshop with and without additional on-field supervisions . Playing exposure , adherence to the 11 + , and injuries were recorded for female 13-year-old to 18-year-old players . Performance testing included the Star Excursion Balance Test ( SEBT ) , single-leg balance , triple hop and jumping-over-a-bar tests . Results Complete preseason and postseason performance tests were available for 226 players ( 66.5 % ) . Compared to the unsupervised group , single-leg balance ( OR=2.8 ; 95 % CI 1.1 to 4.6 ) and the anterior direction of the SEBT improved significantly in the onfield supervised group of players ( OR=4.7 ; 95 % CI 2.2 to 7.1 ) , while 2-leg jumping performance decreased ( OR=−5.1 ; 95 % CI −9.9 to −0.2 ) . However , significant improvements in 5 of 6 reach distances in the SEBT were found , favouring players who highly adhered to the 11 + . Also , injury risk was lower for those players ( injury rate ratio , IRR=0.28 , 95 % CI 0.10 to 0.79 ) . Conclusions Different delivery methods of the FIFA 11 + to coaches influenced players ’ physical performance minimally . However , high player adherence to the 11 + result ed in significant improvements in functional balance and reduced injury risk Objective To study the injury characteristics in professional football and to follow the variation of injury incidence during a match , during a season and over consecutive seasons . Design Prospect i ve cohort study where teams were followed for seven consecutive seasons . Team medical staff recorded individual player exposure and time-loss injuries from 2001 to 2008 . Setting European professional men 's football . Participants The first team squads of 23 teams selected by the Union of European Football Associations as belonging to the 50 best European teams . Main outcome measurement Injury incidence . Results 4483 injuries occurred during 566 000 h of exposure , giving an injury incidence of 8.0 injuries/1000 h. The injury incidence during matches was higher than in training ( 27.5 vs 4.1 , p<0.0001 ) . A player sustained on average 2.0 injuries per season , and a team with typically 25 players can thus expect about 50 injuries each season . The single most common injury subtype was thigh strain , representing 17 % of all injuries . Re-injuries constituted 12 % of all injuries , and they caused longer absences than non re-injuries ( 24 vs 18 days , p<0.0001 ) . The incidence of match injuries showed an increasing injury tendency over time in both the first and second halves ( p<0.0001 ) . Traumatic injuries and hamstring strains were more frequent during the competitive season , while overuse injuries were common during the preseason . Training and match injury incidences were stable over the period with no significant differences between seasons . Conclusions The training and match injury incidences were stable over seven seasons . The risk of injury increased with time in each half of matches Purpose We aim ed to investigate the effect of FIFA 11 + ( 11 + ) and HarmoKnee injury preventive warm-up programs on conventional strength ratio ( CSR ) , dynamic control ratio ( DCR ) and fast/slow speed ratio ( FSR ) in young male professional soccer players . These ratios are related to the risk of injury to the knee in soccer players . Methods Thirty-six players were divided into 3 groups ; FIFA 11 + , HarmoKnee and control ( n = 12 per group ) . These exercises were performed 3 times per week for 2 months ( 24 sessions ) . The CSR , DCR and FSR  were measured before and after the intervention . Results After training , the CSR and DCR of knee muscles in both groups were found to be lower than the published normal values ( 0.61 , 0.72 , and 0.78 during 60 ° .s−1 , 180 ° .s−1 and 300 ° .s−1 , respectively ) . The CSR ( 60 ° .s−1 ) increased by 8 % and FSR in the quadriceps of the non-dominant leg by 8 % in the 11 + . Meanwhile , the DCR in the dominant and non-dominant legs were reduced by 40 % and 30 % respectively in the 11 + . The CSR ( 60 ° .s−1 ) in the non-dominant leg showed significant differences between the 11 + , HarmoKnee and control groups ( p = 0.02 ) . As for the DCR analysis between groups , there were significant differences in the non-dominant leg between both programs with the control group ( p = 0.04 ) . For FSR no significant changes were found between groups . Conclusions It can be concluded that the 11 +  improved CSR and FSR , but the HarmoKnee program did not demonstrate improvement . We suggest adding more training elements to the HarmoKnee program that aim ed to enhance hamstring strength ( CSR , DCR and FSR ) . Professional soccer players have higher predisposition of getting knee injuries because hamstring to quadriceps ratio were found to be lower than the average values . It seems that the 11 + have potentials to improve CSR and FSR as well as prevent knee injuries in soccer players Background : The Fédération Internationale de Football Association ( FIFA ) 11 + program has been shown to be an effective injury prevention program in the female soccer cohort , but there is a paucity of research to demonstrate its efficacy in the male population . Hypothesis : To examine the efficacy of the FIFA 11 + program in men ’s collegiate United States National Collegiate Athletic Association ( NCAA ) Division I and Division II soccer . Study Design : R and omized controlled trial ; Level of evidence , 1 . Methods : Before the commencement of the fall 2012 season , every NCAA Division I and Division II men ’s collegiate soccer team ( N = 396 ) was solicited to participate in this research study . Human ethics review board approval was obtained through Quorum Review IRB . Sixty-five teams were r and omized : 34 to the control group ( CG ; 850 players ) and 31 to the intervention group ( IG ; 675 players ) . Four teams in the IG did not complete the study , reducing the number for analysis to 61 . The FIFA 11 + injury prevention program served as the intervention and was utilized weekly . Athlete-exposures ( AEs ) , compliance , and injury data were recorded using a secure Internet-based system . Results : In the CG , 665 injuries ( mean ± SD , 19.56 ± 11.01 ) were reported for 34 teams , which corresponded to an incidence rate ( IR ) of 15.04 injuries per 1000 AEs . In the IG , 285 injuries ( mean ± SD , 10.56 ± 3.64 ) were reported for 27 teams , which corresponded to an IR of 8.09 injuries per 1000 AEs . Total days missed because of injury were significantly higher for the CG ( mean ± SD , 13.20 ± 26.6 days ) than for the IG ( mean ± SD , 10.08 ± 14.68 days ) ( P = .007 ) . There was no difference for time loss due to injury based on field type ( P = .341 ) . Conclusion : The FIFA 11 + significantly reduced injury rates by 46.1 % and decreased time loss to injury by 28.6 % in the competitive male collegiate soccer player ( rate ratio , 0.54 [ 95 % CI , 0.49 - 0.59 ] ; P < .0001 ) ( number needed to treat = 2.64 ) A prospect i ve study of injuries encountered during participation in a summer soccer camp for youths aged 6 through 17 years revealed an injury incidence of 10.6 per 1000 hours for girls ( 107 injuries in 458 girls ) and 7.3 per 1000 hours for boys ( 109 injuries in 681 boys ) . For both sexes , the incidence of injury increased at age 14 years . One certified athletic trainer ( W.D.C. ) assessed and documented all injuries during the course of the study . Seventy percent of injuries involved the lower extremities . Contusions represented 35.2 % , strains 27.8 % , sprains 19.4 % , and fractures and dislocations 2 % of all reported injuries . The ankle was the most frequent site of injury in both sexes . Quadriceps strain was a common injury in boys . The boys with the highest incidence of injury were tall ( greater than 165 cm ) and had a weak grip ( less than 25 kg ) , suggesting that skeletally mature but muscularly weak boys may be more susceptible to injury while playing soccer with peers of the same chronological age Objective To examine the effect of a comprehensive warm-up programme design ed to reduce the risk of injuries in female youth football . Design Cluster r and omised controlled trial with clubs as the unit of r and omisation . Setting 125 football clubs from the south , east , and middle of Norway ( 65 clusters in the intervention group ; 60 in the control group ) followed for one league season ( eight months ) . Participants 1892 female players aged 13 - 17 ( 1055 players in the intervention group ; 837 players in the control group ) . Intervention A comprehensive warm-up programme to improve strength , awareness , and neuromuscular control during static and dynamic movements . Main outcome measure Injuries to the lower extremity ( foot , ankle , lower leg , knee , thigh , groin , and hip ) . Results During one season , 264 players had relevant injuries  : 121 players in the intervention group and 143 in the control group ( rate ratio 0.71 , 95 % confidence interval 0.49 to 1.03 ) . In the intervention group there was a significantly lower risk of injuries overall ( 0.68 , 0.48 to 0.98 ) , overuse injuries ( 0.47 , 0.26 to 0.85 ) , and severe injuries ( 0.55 , 0.36 to 0.83 ) . Conclusion Though the primary outcome of reduction in lower extremity injury did not reach significance , the risk of severe injuries , overuse injuries , and injuries overall was reduced . This indicates that a structured warm-up programme can prevent injuries in young female football players . Trial registration IS RCT N10306290 Background : Muscle injuries constitute a large percentage of all injuries in football . Purpose : To investigate the incidence and nature of muscle injuries in male professional footballers . Study Design : Cohort study ; Level of evidence , 2 . Methods : Fifty-one football teams , comprising 2299 players , were followed prospect ively during the years 2001 to 2009 . Team medical staff recorded individual player exposure and time-loss injuries . The first-team squads of 24 clubs selected by the Union of European Football Associations as belonging to the best European teams , 15 teams of the Swedish First League , and another 15 European teams playing their home matches on artificial turf pitches were included . A muscle injury was defined as “ a traumatic distraction or overuse injury to the muscle leading to a player being unable to fully participate in training or match play . ” Results : In total , 2908 muscle injuries were registered . On average , a player sustained 0.6 muscle injuries per season . A squad of 25 players can thus expect about 15 muscle injuries per season . Muscle injuries constituted 31 % of all injuries and caused 27 % of the total injury absence . Ninety-two percent of all muscle injuries affected the 4 major muscle groups of the lower limbs : hamstrings ( 37 % ) , adductors ( 23 % ) , quadriceps ( 19 % ) , and calf muscles ( 13 % ) . Sixteen percent of the muscle injuries were reinjuries . These reinjuries caused significantly longer absences than did index injuries . The incidence of muscle injury increased with age . When separated into different muscle groups , however , an increased incidence with age was found only for calf muscle injuries and not for hamstring , quadriceps , or hip/groin strains . Conclusion : Muscle injuries are a substantial problem for players and their clubs . They constitute almost one third of all time-loss injuries in men ’s professional football , and 92 % of all injuries affect the 4 big muscle groups in the lower limbs In this prospect i ve study , injuries in 153 adolescent female soccer players were recorded during one outdoor season ( April-October ) . The overall injury incidence rate was 6.8 per 1000 h soccer ( games and practice ) and the incidence rate of traumatic injury 9.1 and 1.5 per 1000 player-hours in games and practice , respectively . Sixty-three players ( 41 % ) sustained 79 injuries . Sixty-six percent of the injuries were traumatic and 34 % were overuse injuries . Most of the traumatic injuries occurred during games . Eighty-nine percent of the injuries were located in the lower extremities and 42 % occurred in the 
    Output:
    
Conclusion The FIFA 11 + warm-up program  reduced the risk of injury  in soccer players by 30 %