***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 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 BACKGROUND Ankle injuries account for 30 to 60 % of all parachuting injuries . This study was design ed to determine if outside-the-boot ankle braces could reduce ankle sprains during Army paratrooper training . METHODS The r and omized trial involved 777 volunteers from the U.S. Army Airborne School , Fort Benning , Ga. Of this group , 745 completed all study requirements ( 369 brace-wearers and 376 non-brace-wearers ) . Each volunteer made five parachute jumps , for a total of 3,674 jumps . RESULTS The incidence of inversion ankle sprains was 1.9 % in non-brace-wearers and 0.3 % in brace-wearers ( risk ratio , 6.9 ; p = 0.04 ) . Other injuries appeared unaffected by the brace . Overall , 5.3 % of the non-brace group and 4.6 % of the brace group experienced at least one injury . The risk ratio for injured individuals was 1.2:1 ( non-brace to brace groups ; p = 0.65 ) . CONCLUSION Inversion ankle sprains during parachute training can be significantly reduced by using an outside-the-boot ankle brace , with no increase in risk for other injuries Background This study was conducted to investigate whether the most common injuries in soccer could be prevented , and to determine if a simple question naire could identify players at increased risk . Hypothesis Introduction of targeted exercise programs to male soccer players with a history of previous injury or reduced function in the ankle , knee , hamstring , or groin will prevent injuries . Study Design R and omized controlled trial ; Level of evidence , 2 . Methods A total of 508 players representing 31 teams were included in the study . A question naire indicating previous injury and /or reduced function as inclusion criteria was used to divide the players into high-risk ( HR ) ( 76 % ) and low-risk ( LR ) groups . The HR players were r and omized individually into an HR intervention group or HR control group . Results A total of 505 injuries were reported , sustained by 56 % of the players . The total injury incidence was a mean of 3.2 ( 95 % confidence interval [ CI ] , 2.5–3.9 ) in the LR control group , 5.3 ( 95 % Cl , 4.6–6.0 ) in the HR control group ( P = .0001 vs the LR control group ) , and 4.9 ( 95 % Cl , 4.3–5.6 ) in the HR intervention group ( P = .50 vs the HR control group ) . For the main outcome measure , the sum of injuries to the ankle , knee , hamstring , and groin , there was also a significantly lower injury risk in the LR control group compared with the 2 other groups , but no difference between the HR intervention group and the HR control group . Compliance with the training programs in the HR intervention group was poor , with only 27.5 % in the ankle group , 29.2 % in the knee group , 21.1 % in the hamstring group , and 19.4 % in the groin defined as having carried out the minimum recommended training volume . Conclusion The players with a significantly increased risk of injury were able to be identified through the use of a question naire , but player compliance with the training programs prescribed was low and any effect of the intervention on injury risk could not be detected BACKGROUND Shock-absorbing and biomechanic shoe orthoses are frequently used in the prevention and treatment of back and lower extremity problems . One review concludes that the former is clinical ly effective in relation to prevention , whereas the latter has been tested in only 1 r and omized clinical trial , concluding that stress fractures could be prevented . OBJECTIVES To investigate if biomechanic shoe orthoses can prevent problems in the back and lower extremities and if reducing the number of days off-duty because of back or lower extremity problems is possible . DESIGN Prospect i ve , r and omized , controlled intervention trial . STUDY SUBJECTS One female and 145 male military conscripts ( aged 18 to 24 years ) , representing 25 % of all new conscripts in a Danish regiment . METHOD Health data were collected by question naires at initiation of the study and 3 months later . Custom-made biomechanic shoe orthoses to be worn in military boots were provided to all in the study group during the 3-month intervention period . No intervention was provided for the control group . Differences between the 2 groups were tested with the chi-square test , and statistical significance was accepted at P < .05 . Risk ratio ( RR ) , risk difference ( ARR ) , numbers needed to prevent ( NNP ) , and cost per successfully prevented case were calculated . OUTCOME VARIABLES Outcome variables included self-reported back and /or lower extremity problems ; specific problems in the back or knees or shin splints , Achilles tendonitis , sprained ankle , or other problems in the lower extremity ; number of subjects with at least 1 day off-duty because of back or lower extremity problems and total number of days off-duty within the first 3 months of military service because of back or lower extremity problems . RESULTS Results were significantly better in an actual-use analysis in the intervention group for total number of subjects with back or lower extremity problems ( RR 0.7 , ARR 19 % , NNP 5 , cost 98 US dollars ) ; number of subjects with shin splints ( RR 0.2 , ARR 19 % , NNP 5 , cost 101 US dollars ) ; number of off-duty days because of back or lower extremity problems ( RR 0.6 , ARR < 1 % , NNP 200 , cost 3750 US dollars ) . In an intention-to-treat analysis , a significant difference was found for only number of subjects with shin splints ( RR 0.3 , ARR 18 % , NNP 6 cost 105 US dollars ) , whereas a worst-case analysis revealed no significant differences between the study groups . CONCLUSIONS This study shows that it may be possible to prevent certain musculoskeletal problems in the back or lower extremities among military conscripts by using custom-made biomechanic shoe orthoses . However , because care-seeking for lower extremity problems is rare , using this method of prevention in military conscripts would be too costly . We also noted that the choice of statistical approach determined the outcome To study the efficacy of an injury prevention program in a r and omized trial , 12 teams ( 180 players ) in a male senior soccer division were followed up for 6 months . The 12 teams were allocated at r and om to two groups of six teams , one being given a prophylactic program and the other serving as control . The program was based on previous studies of injury mechanisms . It comprised ( 1 ) correction of training , ( 2 ) provision of optimum equipment ; ( 3 ) prophylactic ankle taping ; ( 4 ) controlled rehabilitation ; ( 5 ) exclusion of players with grave knee instability ; ( 6 ) information about the impor tance of disciplined play and the increased risk of injury at training camps ; and ( 7 ) correction and supervision by doctor(s ) and physiotherapist(s ) . The injuries in the test teams were 75 % fewer than in the controls . The most common types of soccer injuries , sprains and strains to ankles and knees , were all significantly reduced . It is concluded that the pro posed prophylactic program , including close supervi sion and correction by doctors and physiotherapists , significantly reduces soccer injuries Abstract . This prospect i ve r and omized intervention investigated whether training on a balance board could reduce the amount of traumatic injuries of the lower extremities in female soccer players . A total of 221 female soccer players from 13 different teams playing in the second and third Swedish divisions volunteered to participate in the study . Seven teams ( n=121 ) were r and omized to an intervention group and six teams ( n=100 ) to a control group and were followed during one outdoor season ( April – October ) . Before and after the season muscle flexibility and balance/postural sway of the lower extremities were measured in the players . There were no significant differences in age , height , weight , muscle flexibility and balance/postural sway of the lower extremities between the intervention and the control group . During the season the players in the intervention group performed a special training program consisting of 10–15 min of balance board training in addition to their st and ard soccer practice and games . After a 37 % drop-out the intervention group consisted of 62 players and the control group of 78 players . The results showed no significant differences between the groups with respect either to the number , incidence , or type of traumatic injuries of the lower extremities . The incidence rate of " major " injuries was higher in the intervention group than in the control group . Four of five anterior cruciate ligament injuries occurred in the intervention group , which means that we could not prevent severe knee injuries in female soccer players with balance board training . However , among the players who had been injured during the 3-month period prior to this investigation there were significantly more players from the control group than from the intervention group who sustained new injuries during the study period BACKGROUND Concussion is a serious problem in many contact sports , including rugby union football . The study 's primary aim was to measure the efficacy of padded headgear in reducing the rates of head injury or concussion . METHODS A cluster r and omized controlled trial with three arms was conducted with rugby union football teams as the unit of r and omization . Teams consisted of males participating in under 13- , 15- , 18- , and 20-yr age group competitions . The interventions were " st and ard " and " modified " padded headgear .  Headgear wearing and injury were measured for each study team at each game over two seasons . RESULTS Eighty-two teams participated in year 1 and 87 in year 2 . A total of 1493 participants ( 10,040 player hours ) were in the control group , 1128 participants ( 8170 player hours ) were assigned to the st and ard headgear group , and 1474 participants ( 10,650 player hours ) were assigned to the modified headgear group .  The compliance rates were low in all groups , but 46 % of participants wore st and ard headgear . An intention-to-treat analysis showed no differences in the rates of head injury or concussion between controls and headgear arms . Incidence rate ratios for st and ard headgear wearers referenced to controls were 0.95 and 1.02 for game and missed game injuries . Analyses of injury rates based on observed wearing patterns also showed no significant differences . Incidence rate ratios for st and ard headgear wearers referenced to nonwearers were 1.11 and 1.10 for game and missed game injuries . CONCLUSIONS Padded headgear does not reduce the rate of head injury or concussion . The low compliance rates are a limitation . Although individuals may choose to wear padded headgear , the routine or m and atory use of protective headgear can not be recommended 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 
    Output:
    
Conclusions This meta- analysis showed that certain interventions can reduce the risk of sports injuries .