***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 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 Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more Background A soccer-specific balance training has been shown to decrease injury incidence of the anterior cruciate ligament and ankle sprains in r and omized controlled trials . However , hamstring injuries and tendinopathy remain significant issues in soccer . Hypothesis Proprioceptive training can reduce the incidence of hamstring muscle injuries and tendinopathy in elite soccer . There is a dose-effect relationship between balance training duration and injury incidence . Study Design Cohort study ; Level of evidence , 3 . Methods Twenty-four elite female soccer players ( body mass index , 21.7 ± 1.2 ; age , 21 ± 4 years ) of a German premier league soccer team were prospect ively included . Starting in January 2004 , an additional soccer-specific proprioceptive multistation training was initiated over 3 years . Injury data /1000 hours of exposure with documentation of all occurred injuries , detailed training , and match exposure data as well as time loss data were 100 % complete . Results At the end of the 3-year proprioceptive balance training intervention , noncontact hamstring injury rates were reduced from 22.4 to 8.2/1000 hours ( P = .021 ) , patellar tendinopathy from 3.0 to 1.0/1000 hours ( P = .022 ) , and Achilles tendinopathy from 1.5 to 0.0/1000 hours ( P = .035 ) . There was no effect of balance training on contact injuries . Mean time loss of all assessed injuries significantly decreased from 14.4 days during the control period to 1.5 days during intervention periods ( P = .003 ) . The more minutes of balance training performed , the lower the rate of overall injuries ( r = −0.185 , P = .001 ) , hamstring injuries ( r = −0.267 , P = .003 ) , patellar tendinopathy ( r = −0.398 , P = .02 ) , and gastrocnemius strains ( r = −0.342 , P = .002 ) . Conclusion Soccer-specific balance training ( protective balancing ) can reduce noncontact hamstring injuries and patellar and Achilles tendinopathy . A dose-effect relationship between duration of balance training and injury incidence is evident . A proprioceptive training program reduced the rehabilitation time in noncontact injuries , which warrants further investigation Non-r and omised studies of the effects of interventions are critical to many areas of healthcare evaluation , but their results may be biased . It is therefore important to underst and and appraise their strengths and weaknesses . We developed ROBINS-I ( “ Risk Of Bias In Non-r and omised Studies - of Interventions ” ) , a new tool for evaluating risk of bias in estimates of the comparative effectiveness ( harm or benefit ) of interventions from studies that did not use r and omisation  to allocate units ( individuals or clusters of individuals ) to comparison groups . The tool will be particularly useful to those undertaking systematic review s that include non-r and omised studies 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 ‘ More research is needed ’ is a most unhelpful conclusion for the clinician reader of a systematic review . Clinicians look to research ers for the ‘ research evidence ’ part of Professor Sackett ’s ‘ three circles ’ of evidence -based practice .1 The clinician can not ignore the patient in front of him or her just because there is no evidence from systematic review s or r and omised controlled trials ( RCTs ): ‘ Kindly forget about your shoulder problem , until we have better research to tell me what to do ’ ? This will not do ! In this editorial , we share three practical tips for authors synthesis ing lower level evidence in systematic review s , when high- quality RCTs are absent . Our goal is to help authors help clinicians help patients . Consider the patient who plays tennis and presents with shoulder pain . Right now , the clinician who is seeking RCT evidence on how to progress from impairment-focused tasks in neutral shoulder positions to high-level , sport-specific tasks will be disappointed . Being able to function in shoulder elevation positions above The purpose was to test the effect of eccentric strength training and flexibility training on the incidence of hamstring strains  in soccer . Hamstring strains and player exposure were registered prospect ively during four consecutive soccer seasons ( 1999 - 2002 ) for 17 - 30 elite soccer teams from Icel and and Norway . The first two seasons were used as baseline , while intervention programs consisting of warm-up stretching , flexibility and /or eccentric strength training were introduced during the 2001 and 2002 seasons . During the intervention seasons , 48 % of the teams selected to use the intervention programs . There was no difference in the incidence of hamstring strains between teams that used the flexibility training program and those who did not [ relative risk (RR)=1.53 , P=0.22 ] , nor was there a difference compared with the baseline data ( RR=0.89 , P=0.75 ) . The incidence of hamstring strains was lower in teams who used the eccentric training program compared with teams that did not use the program ( RR=0.43 , P=0.01 ) , as well as compared with baseline data for the same intervention teams ( RR=0.42 , P=0.009 ) . Eccentric strength training with Nordic hamstring lowers combined with warm-up stretching appears to reduce the risk of hamstring strains , while no effect was detected from flexibility training alone . These results should be verified in r and omized clinical trials PURPOSE To analyze the effect of an eccentric-overload training program ( ie , half-squat and leg-curl exercises using flywheel ergometers ) with individualized load on muscle-injury incidence and severity and performance in junior elite soccer players . METHODS Thirty-six young players ( U-17 to U-19 ) were recruited and assigned to an experimental ( EXP ) or control group ( CON ) . The training program consisted of 1 or 2 sessions/wk ( 3 - 6 sets with 6 repetitions ) during 10 wk . The outcome measured included muscle injury ( incidence per 1000 h of exposure and injury severity ) and performance tests ( countermovement jump [ CMJ ] , 10-m and 20-m sprint test ) . RESULTS Between-groups results showed a likely ( ES : 0.94 ) lower number of days of absence per injury and a possible decrement of incidence per 1000 h of match play in EXP than in CON . Regarding muscle performance , a substantial better improvement ( likely to very likely ) was found in 20-m sprint time ( ES : 0.37 ) , 10-m flying-sprint time ( ES : 0.77 ) , and CMJ ( ES : 0.79 ) for EXP than for CON . Within-group analysis showed an unclear effect in each variable in CON . Conversely , substantial improvements were obtained in CMJ ( ES : 0.58 ) , 20-m sprint time ( ES : 0.32 ) , 10-m flying-sprint time ( ES : 0.95 ) , and injury severity ( ES : 0.59 ) in EXP . Furthermore , a possible decrement in total injury incidence was also reported in EXP . CONCLUSIONS The eccentric-based program led to a reduction in muscle-injury incidence and severity and showed improvements in common soccer tasks such as jumping ability and linear-sprinting speed R and omised controlled trials are the best way to compare the effectiveness of different interventions . Only r and omised trials allow valid inferences of cause and effect . Only r and omised trials have the potential directly to affect patient care — occasionally as single trials but more often as the body of evidence from several trials , whether or not combined formally by meta- analysis . It is thus entirely reasonable to require higher st and ards for papers reporting r and omised trials than those describing other types of study . Like all studies , r and omised trials are open to bias if done badly.1 It is thus essential that r and omised trials are done well and reported adequately . Readers should not have to infer what was probably done , they should be told explicitly . Proper methodology should be used and be seen to have been used . Yet review s of published trials have consistently found major deficiencies in reporting,2 3 4 making the task Research and discussion s about injury rates and their prevention in elite football is one of the hottest topics in the medical and sport science literature . Over the past years , there has been an explosion of the number of publications , including surveys,1 observational , retrospective or prospect ive2 studies , training interventions and various types of expert opinions and commentaries.3 This array of information are likely useful to improve our underst and ing of what the best practice s may be and , in turn , increase our ability to better prepare , manage and treat players . However , a recent survey has shown that 83 % of UEFA clubs do not follow evidence d-based prevention programmes.1 It was also shown that hamstring injuries kept increasing over the last 13 years.2 Taken together , those two papers may suggest that the majority of elite club practitioners likely disregard research findings 1 and may therefore be the one to be blamed for those increased injury rates.2 Making supporting staff and coaches responsible for those injuries is easy , especially when considering their perceived typical personality traits ( ie , so-called type 2,4 high egos and little open-mindedness and willingness to learn—‘why could they be bothered applying the new study findings ? ’ ) . While this may be true sometimes , the reality is that The primary purpose of this study was to evaluate whether a preseason strength training programme for the hamstring muscle group - emphasising eccentric overloading - could affect the occurrence and severity of hamstring injuries during the subsequent competition season in elite male soccer players . Thirty players from two of the best premier- 
    Output:
    
We found limited scientific evidence to support exercise-based strategies to prevent muscle injury in elite footballers .