***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: OBJECTIVE To define the causes of injuries to players in English professional football during competition and training . METHOD Lost time injuries to professional and youth players were prospect ively recorded by physiotherapists at four English League clubs over the period 1994 to 1997 . Data recorded included information related to the injury , date and place of occurrence , type of activity , and extrinsic Playing factors . RESULTS In all , 67 % of all injuries occurred during competition . The overall injury frequency rate ( IFR ) was 8.5 injuries/1000 hours , with the IFR during competitions ( 27.7 ) being significantly ( p < 0.01 ) higher than that during training ( 3.5 ) . The IFRs for youth players were found to increase over the second half of the season , whereas they decreased for professional players . There were no significant differences in IFRs for professional and youth players during training . There were significantly ( p < 0.01 ) injuries in competition in the 15 minute periods at the end of each half . Strains ( 41 % ) , sprains ( 20 % ) , and contusions ( 20 % ) represented the major types of injury . The thigh ( 23 % ) , the ankle ( 17 % ) , knee ( 14 % ) , and lower leg ( 13 % ) represented the major locations of injury , with significantly ( p < 0.01 ) more injuries to the dominant body side . Reinjury counted for 22 % of all injuries . Only 12 % of all injuries were caused by a breach of the rules of football , although player to player contact was involved in 41 % of all injuries . CONCLUSIONS The overall level of injury to professional footballers has been showed to be around 1000 times higher times higher than for industrial occupations generally regarded as high risk . The high level of muscle strains , in particular , indicates possible weakness in fitness training programmes and use of warming up and cooling down procedures by clubs and the need for benchmarking players ' levels of fitness and performance . Increasing levels of injury to youth players as a season progresses emphasizes the importance of controlling the exposure of young players to high levels of competition Objectives —To undertake a prospect i ve epidemiological study of the injuries sustained in English professional football over two competitive seasons . Methods —Player injuries were annotated by club medical staff at 91 professional football clubs . A specific injury audit question naire was used together with a weekly form that documented each club 's current injury status . Results —A total of 6030 injuries were reported over the two seasons with an average of 1.3 injuries per player per season . The mean ( SD ) number of days absent for each injury was 24.2 ( 40.2 ) , with 78 % of the injuries leading to a minimum of one competitive match being missed . The injury incidence varied throughout the season , with training injuries peaking during July ( p<0.05 ) and match injuries peaking during August ( p<0.05 ) . Competition injuries represented 63 % of those reported , significantly ( p<0.01 ) more of these injuries occurring towards the end of both halves . Strains ( 37 % ) and sprains ( 19 % ) were the major injury types , the lower extremity being the site of 87 % of the injuries reported . Most injury mechanisms were classified as being non-contact ( 58 % ) . Re-injuries accounted for 7 % of all injuries , 66 % of these being classified as either a strain or a sprain . The severity of re-injuries was greater than the initial injury ( p<0.01 ) . Conclusions —Professional football players are exposed to a high risk of injury and there is a need to investigate ways of reducing this risk . Areas that warrant attention include the training programmes implemented by clubs during various stages of the season , the factors contributing to the pattern of injuries during matches with respect to time , and the rehabilitation protocol s employed by clubs BACKGROUND In spite of ongoing prevention developments , anterior cruciate ligament injury rates and the associated sex-disparity have remained , suggesting an incomplete underst and ing of the injury mechanism . While both fatigue and decision making are known in isolation to directly impact anterior cruciate ligament injury risk , their combined manifestations remain unknown . We thus examined the combined effects of fatigue and decision making on lower limb kinematics during sports relevant l and ings . METHODS Twenty five female National College Athletic Association athletes had initial contact and peak stance phase 3D lower limb joint kinematics quantified during anticipated and unanticipated single ( left and right ) leg l and ings , both before and during the accumulation of fatigue . Jump direction was governed by light stimuli activated prior to and during the pre-l and phase of respective anticipated and unanticipated trials . To induce fatigue , subjects performed repetitive squat ( n=5 ) and r and omly ordered jump sequences , until squats were no longer possible . Subject-based measures of each dependent factor were then calculated across pre-fatigue trials , and for those denoting 100 % and 50 % fatigue , and su bmi tted to a 3-way mixed design analysis of covariance to test for the main effects of fatigue time , decision and leg . FINDINGS Fatigue caused significant increases in initial contact hip extension and internal rotation , and in peak stance knee abduction and internal rotation and ankle supination angles . Fatigue-induced increases in initial contact hip rotations and in peak knee abduction angle were also significantly more pronounced during unanticipated compared to anticipated l and ings . INTERPRETATION The integrative effects of fatigue and decision making may represent a worst case scenario in terms of anterior cruciate ligament injury risk during dynamic single leg l and ings , by perpetuating substantial degradation and overload of central control mechanisms OBJECTIVE : To test the feasibility of creating a valid and reliable checklist with the following features : appropriate for assessing both r and omised and non-r and omised studies ; provision of both an overall score for study quality and a profile of scores not only for the quality of reporting , internal validity ( bias and confounding ) and power , but also for external validity . DESIGN : A pilot version was first developed , based on epidemiological principles , review s , and existing checklists for r and omised studies . Face and content validity were assessed by three experienced review ers and reliability was determined using two raters assessing 10 r and omised and 10 non-r and omised studies . Using different raters , the checklist was revised and tested for internal consistency ( Kuder-Richardson 20 ) , test-retest and inter-rater reliability ( Spearman correlation coefficient and sign rank test ; kappa statistics ) , criterion validity , and respondent burden . MAIN RESULTS : The performance of the checklist improved considerably after revision of a pilot version . The Quality Index had high internal consistency ( KR-20 : 0.89 ) as did the subscales apart from external validity ( KR-20 : 0.54 ) . Test-retest ( r 0.88 ) and inter-rater ( r 0.75 ) reliability of the Quality Index were good . Reliability of the subscales varied from good ( bias ) to poor ( external validity ) . The Quality Index correlated highly with an existing , established instrument for assessing r and omised studies ( r 0.90 ) . There was little difference between its performance with non-r and omised and with r and omised studies . Raters took about 20 minutes to assess each paper ( range 10 to 45 minutes ) . CONCLUSIONS : This study has shown that it is feasible to develop a checklist that can be used to assess the method ological quality not only of r and omised controlled trials but also non-r and omised studies . It has also shown that it is possible to produce a checklist that provides a profile of the paper , alerting review ers to its particular method ological strengths and weaknesses . Further work is required to improve the checklist and the training of raters in the assessment of external validity Background Altered motor control strategies in l and ing and jumping maneuvers are a potential mechanism of noncontact anterior cruciate ligament injury . There are biomechanical differences between male and female athletes in the l and ing phase of stop-jump tasks . Fatigue is a risk factor in musculoskeletal injuries . Hypothesis Lower extremity muscle fatigue alters the knee kinetics and kinematics during the l and ing phase of 3 stop-jump tasks and increases an athlete 's risk of anterior cruciate ligament injury . Study Design Controlled laboratory study . Methods Three-dimensional videography and force plate data were collected for 20 recreational athletes ( 10 male and 10 female athletes ) performing 3 stop-jump tasks before and after completing a fatigue exercise .  Knee joint angles and result ant forces and moments were calculated . Results Both male and female subjects had significantly increased peak proximal tibial anterior shear forces ( P = . 01 ) , increased valgus moments ( P = . 03 ) , and decreased knee flexion angles ( P = . 03 ) during l and ings of all 3 stop-jump tasks when fatigued . Fatigue did not significantly affect the peak knee extension moment for male or female athletes . Conclusion Fatigued recreational athletes demonstrate altered motor control strategies , which may increase anterior tibial shear force , strain on the anterior cruciate ligament , and risk of injury for both female and male subjects . Clinic Relevance Fatigued athletes may have an increased risk of noncontact anterior cruciate ligament injury The aim of this study was to examine the influence of perceived intensity , duration and load of matches and training on the incidence of injury in rugby league players . The incidence of injury was prospect ively studied in 79 semi-professional rugby league players during the 2001 season . All injuries sustained during matches and training sessions were recorded . Training sessions were conducted from December to September , with matches played from February to September . The intensity of individual training sessions and matches was estimated using a modified rating of perceived exertion scale . Training load was calculated by multiplying the training intensity by the duration of the training session . The match load was calculated by multiplying the match intensity by the time each player participated in the match . Training load increased from December ( 278.3 [ 95 % confidence interval , CI 262.2 to 294.5 ] units ) to February ( 385.5 [ 95 % CI 362.4 to 408.5 ] units ) , followed by a decline until September ( 98.4 [ 95 % CI 76.5 to 120.4 ] units ) . Match load increased from February ( 204.0 [ 95 % CI 186.2 to 221.8 ] units ) to September ( 356.8 [ 95 % CI 302.5 to 411.1 ] units ) . More training injuries were sustained in the first half of the season ( first vs second : 69.2 % vs 30.8 % , P < 0.001 ) , whereas match injuries occurred more frequently in the latter stages of the season ( 53.6 % vs 46.4 % , P < 0.001 ) . A significant relationship ( P < 0.05 ) was observed between changes in training injury incidence and changes in training intensity ( r = 0.83 ) , training duration ( r = 0.79 ) and training load ( r = 0.86 ) . In addition , changes in the incidence of match injuries were significantly correlated ( P < 0.05 ) with changes in match intensity ( r = 0.74 ) , match duration ( r = 0.86 ) and match load ( r = 0.86 ) . These findings suggest that as the intensity , duration and load of rugby league training sessions and matches is increased , the incidence of injury is also increased Background Female athletes participating in high-risk sports suffer anterior cruciate ligament injury at a 4- to 6-fold greater rate than do male athletes . Hypothesis Prescreened female athletes with subsequent anterior cruciate ligament injury will demonstrate decreased neuromuscular control and increased valgus joint loading , predicting anterior cruciate ligament injury risk . Study Design Cohort study ; Level of evidence , 2 . Methods There were 205 female athletes in the high-risk sports of soccer , basketball , and volleyball prospect ively measured for neuromuscular control using 3-dimensional kinematics ( joint angles ) and joint loads using kinetics ( joint moments ) during a jump-l and ing task . Analysis of variance as well as linear and logistic regression were used to isolate predictors of risk in athletes who subsequently ruptured the anterior cruciate ligament . Results Nine athletes had a confirmed anterior cruciate ligament rupture ; these 9 had significantly different knee posture and loading compared to the 196 who did not have anterior cruciate ligament rupture . Knee abduction angle ( P < . 05 ) at l and ing was 8 ° greater in anterior cruciate ligament-injured than in uninjured athletes . Anterior cruciate ligament-injured athletes had a 2.5 times greater knee abduction moment ( P < . 001 ) and 20 % higher ground reaction force ( P < . 05 ) , whereas stance time was 16 % shorter ; hence , increased motion , force , and moments occurred more quickly . Knee abduction moment predicted anterior cruciate ligament injury status with 73 % specificity and 78 % sensitivity ; dynamic valgus measures showed a predictive r2 of 0.88 . Conclusion Knee motion and knee loading during a l and ing task are predictors of anterior cruciate ligament injury risk in female athletes . Clinical Relevance Female athletes with increased dynamic valgus and high abduction loads are at increased risk of anterior cruciate ligament injury . The methods developed may be used to monitor neuromuscular control of the knee joint and may help develop simpler measures of neuromuscular control that can be used to direct female athletes to more effective , targeted interventions Background Female athletes are at significantly greater risk of anterior cruciate ligament ( ACL ) injury than male athletes in the same high-risk sports . Decreased trunk ( core ) neuromuscular control may compromise dynamic knee stability . Hypotheses ( 1 ) Increased trunk displacement after sudden force 
    Output:
    
There was some evidence to show that vertical ground reaction forces and hip and knee joint moments were reduced after fatigue .
The current body of studies showed mixed findings , particularly in relation to l and ing kinematics after fatigue .