***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 BACKGROUND There are no controlled , prospect i ve studies comparing the 10-year outcomes of anterior cruciate ligament ( ACL ) reconstruction using patellar tendon ( PT ) and 4-str and hamstring tendon ( HT ) autografts . HYPOTHESIS Comparable results are possible with HT and PT autografts . STUDY DESIGN Cohort study ; Level of evidence , 2 . METHODS One hundred eighty ACL-deficient knees that met inclusion criteria underwent ACL reconstruction ( 90 HT autograft , 90 PT autograft ) by one surgeon and were treated with an accelerated rehabilitation program . All knees were observed in a prospect i ve fashion with subjective , objective , and radiographic evaluation at 2 , 5 , 7 , and 10-year intervals . RESULTS At 10 years , there were no differences in graft rupture rates ( 7/90 PT vs. 12/90 HT , P = .24 ) . There were 20 contralateral ACL ruptures in the PT group , compared with 9 in the HT group ( P = .02 ) . In all patients , graft rupture was associated with instrumented laxity > 2 mm at 2 years ( P = .001 ) . Normal or near-normal function of the knee was reported in 97 % of patients in both groups . In the PT group , harvest-site symptoms ( P = .001 ) and kneeling pain ( P = .01 ) were more common than in the HT group . More patients reported pain with strenuous activities in PT knees than in HT knees ( P = .05 ) . Radiographic osteoarthritis was more common in PT knees than the HT-reconstructed knees ( P = .04 ) . The difference , however , was composed of patients with mild osteoarthritis . Other predictors of radiographic osteoarthritis were < 90 % single-legged hop test at 1 year and the need for further knee surgery . An " ideal " outcome , defined as an overall International Knee Documentation Committee grade of A or B and a radiographic grade of A at 10 years after ACL reconstruction , was associated with <3 mm of instrumented laxity at 2 years , the absence of additional surgery in the knee , and HT grafts . CONCLUSIONS It is possible to obtain excellent results with both HT and PT autografts . We recommend HT reconstructions to our patients because of decreased harvest-site symptoms and radiographic osteoarthritis Background In sports involving pivoting and l and ing , female athletes suffer knee injury at a greater rate than male athletes . Hypotheses Proprioceptive deficits in control of the body 's core may affect dynamic stability of the knee . Female , but not male , athletes who suffered a knee injury during a 3-year follow-up period would demonstrate decreased core proprioception at baseline testing as compared with uninjured athletes . Study Design Cohort study ( prognosis ) ; Level of evidence , 2 . Methods Study subjects were 277 collegiate athletes ( 140 female , 137 male ) who were prospect ively tested for core proprioception by active and passive proprioceptive repositioning .  Athletes were monitored for injury for 3 years . An ANOVA and multivariate logistic regression were used to test whether core proprioception was related to knee injuries in athletes . Results Twenty-five athletes sustained knee injuries ( 11 women , 14 men ) . Deficits in active proprioceptive repositioning were observed in women with knee injuries ( 2.2 ° ) and ligament/meniscal injuries ( 2.4 ° ) compared with uninjured women ( 1.5 ° , P ≤ .05 ) . There were no differences in average active proprioceptive repositioning error between injured men and uninjured men ( P ≥ .05 ) . Uninjured women demonstrated significantly less average error in active proprioceptive repositioning than uninjured men ( 1.5 ° vs 1.7 ° , P ≤ .05 ) . For each degree increase in average active proprioceptive repositioning error , a 2.9-fold increase in the odds ratio of knee injury was observed , and a 3.3-fold increase in odds ratio of ligament/meniscal injury was observed ( P ≤ .01 ) . Active proprioceptive repositioning predicted knee injury status with 90 % sensitivity and 56 % specificity in female athletes . Conclusions Impaired core proprioception , measured by active proprioceptive repositioning of the trunk , predicted knee injury risk in female , but not male , athletes OBJECTIVE To determine the relation of hamstring and quadriceps muscle strength and imbalance to hamstring injury using a prospect i ve observational cohort study METHOD A total of 102 senior male Australian Rules footballers aged 22.2 ( 3.6 ) years were tested at the start of a football season .  Maximum voluntary concentric and eccentric torque of the hamstring and quadriceps muscles of both legs was assessed using a Kin-Com isokinetic dynamometer at angular velocities of 60 and 180 degrees/second .  Twelve ( 11.8 % ) players sustained clinical ly diagnosed hamstring strains which caused them to miss one or more matches over the ensuing season . RESULTS There were no significant differences for any of the isokinetic variables comparing the injured and non-injured legs in players with unilateral hamstring strains ( n=9 ) . Neither the injured nor the non-injured leg of injured players differed from the mean of left and right legs in non-injured players for any isokinetic variable . The hamstring to opposite hamstring ratios also did not differ between injured and non-injured players . A hamstring to opposite hamstring ratio of less than 0.90 and a hamstring to quadriceps ratio of less than 0.60 were not associated with an increased risk of hamstring injury . A significantly greater percentage of players who sustained a hamstring strain reported a history of hamstring strain compared with non-injured players ( p=0.02 ) . However , this was not related to muscle weakness or imbalance . CONCLUSIONS Isokinetic muscle strength testing was not able to directly discriminate Australian Rules football players at risk for a hamstring injury Eighty-six male high school ice hockey players partic ipated in this prospect i ve study to determine both the incidence of injury in high school ice hockey and the influence of physical , situational , and psychosocial fac tors . Physical factors included height , weight , vision , previous injuries , musculoskeletal abnormalities , and injuries present at the time of screening evaluations . Situational factors examined were level of participa tion , playing time , player position , and games versus practice s. Psychosocial factors such as confidence , stress , social support , positive states of mind , and mood states were also examined to determine their influences on injury . Twenty-seven injuries occurred during the 1994 to 1995 season . As hypothesized , the overall incidence of injury in high school hockey games ( 34.4 per 1000 player-game hours ) was less than the incidence of injury in Junior A hockey ( 96.1 per 1000 player-game hours ) and was more than previously re ported for Bantam youth hockey ( 10.9 per 1000 player- game hours ) . Injuries occurred more often in games than in practice s , usually as a result of collisions . Phys ical factors such as player position and previous inju ries did not significantly predict injuries , but players in the high playing time group were more likely to be injured . Psychosocial factors of low vigor and high fatigue as measured by the Incredibly Short Profile of Mood States ( ISPOMS ) significantly predicted high school ice hockey injuries Background The injury risk in football is high , but little is known about causes of injury . Purpose To identify risk factors for football injuries using a multivariate model . Study Design Prospect i ve cohort study . Methods Participants were 306 male football players from the two highest divisions in Icel and . Before the 1999 football season started , the following factors were examined : height , weight , body composition , flexibility , leg extension power , jump height , peak O2 uptake , joint stability , and history of previous injury . Injuries and player exposure were recorded throughout the competitive season . Results Older players were at higher risk of injury in general ( odds ratio [ OR ] = 1.1 per year , P = 0.05 ) . For hamstring strains , the significant risk factors were age ( OR = 1.4 [ 1 year ] , P < 0.001 ) and previous hamstring strains ( OR = 11.6 , P < 0.001 ) . For groin strains , the predictor risk factors were previous groin strains ( OR = 7.3 , P = 0.001 ) and decreased range of motion in hip abduction ( OR = 0.9 [ 1 ° ] , P = 0.05 ) . Previous injury was also identified as a risk factor for knee ( OR = 4.6 ) and ankle sprains ( OR = 5.3 ) . Conclusions Age and previous injury were identified as the main risk factors for injury among elite football players from Icel and This prospect i ve study was conducted to determine whether hip muscle strength and flexibility play a role in the incidence of adductor and hip flexor strains in National Hockey League ice hockey team players .  Hip flexion , abduction , and adduction strength were measured in 81 players before two consecutive seasons . Thirty-four players were cut , traded , or sent to the minor league before the beginning of the season . Injury and individual exposure data were recorded for the remaining 47 players . Eight players experienced 11 adductor muscle strains , and there were 4 hip flexor strains . Preseason hip adduction strength was 18 % lower in the players who subsequently sustained an adductor muscle strain compared with that of uninjured players . Adduction strength was 95 % of abduction strength in the uninjured players but only 78 % of abduction strength in the injured players . Preseason hip adductor flexibility was not different between players who sustained adductor muscle strains and those who did not . These results indicate that preseason hip strength testing of professional ice hockey players can identify players at risk of developing adductor muscle strains . A player was 17 times more likely to sustain an adductor muscle strain if his adductor strength was less than 80 % of his abductor strength This work was supported by NIH grant P50-AR39221 . The purpose of this study was to determine intraobserver and interobserver reliability using a Cybex II isokinetic dynamometer for the measurement of isometric and isokinetic strength ( 0 , 60 , 180 , 300 degrees /sec ) and endurance ( 240 degrees /sec ) in 20 healthy untrained females . Subjects were r and omly assigned to one of two testers . Intraobserver reliability coefficients for tester one and tester two ranged from 0.89 to 0.98 and 0.72 to 0.97 , respectively . Interobserver reliability coefficients ranged from 0.69 to 0.95 across speeds and movements . Although the testers differed significantly in reliability ( p < 0.01 ) , no systematic differences in measured levels of performance were noted between testers one and two for the majority of the measurements . The results indicate that comparable muscular strength and endurance values can be obtained from knee extension/flexion tests at various speeds using a Cybex II isokinetic dynamometer . Comparable values were obtained whether subjects were tested by a single tester on two separate occasions or whether subjects were tested by a different tester on two separate occasions . J Orthop Sports Phys Ther 1991;14(1):37 - 41 Background : Ankle sprains are a common and potentially disabling injury . Successful prediction of susceptibility to ankle sprain injury with a simple test could allow ankle sprain prevention protocol s to be initiated and help prevent disability in the athletic population . Objective : To 
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RESULTS The analysis showed that different screening tools can be predictive for injuries to the knee , ACL , hamstring , groin and ankle .
For injuries in general there is some support in the literature to suggest that general joint laxity is a predictive measure for leg injuries .
The anterior right/left reach distance > 4 cm and the composite reach distance < 4.0 % of limb length in girls measured with the star excursion balance test ( SEBT ) may predict leg injuries .
Furthermore , an increasing age , a lower hamstring/quadriceps ( H : Q ) ratio and a decreased range of motion ( ROM ) of hip abduction may predict the occurrence of leg injuries .
Hyperextension of the knee , side-to-side differences in anterior-posterior knee laxity and differences in knee abduction moment between both legs are suggested to be predictive tests for sustaining an ACL injury and height was a predictive screening tool for knee ligament injuries .
Hip-adduction-to-abduction strength is a predictive test for hip adductor muscle strain .
Studies do not agree on whether ROM of the hamstring is a predictive screening tool for groin injury .
Body mass index and the age of an athlete could contribute to an ankle sprain .
There is support in the literature to suggest that greater strength of the plantar flexors may be a predictive measure for sustaining an ankle injury .
Furthermore , there is some agreement that the measurement of postural sway is a predictive test for an ankle injury .