***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 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 Hamstring muscle strain is one of the most common injuries in sports . Still , knowledge is limited about the progression of clinical and magnetic resonance imaging characteristics and their association with recovery time in athletes . Hypothesis Knowing the anatomical location and extent of an acute first-time hamstring strain in athletes is critical for the prognosis of recovery time . Study Design Case series ( prognosis ) ; Level of evidence , 2 . Methods Eighteen elite sprinters with acute first-time hamstring strains were prospect ively included in the study . All subjects were examined , clinical ly and with magnetic resonance imaging , on 4 occasions after injury : at day 2 to 4 , 10 , 21 , and 42 . The clinical follow-up period was 2 years . Results All sprinters were injured during competitive sprinting , and the primary injuries were all located in the long head of the biceps femoris muscle . There was an association between the time to return to pre-injury level ( median , 16 ; range , 6 - 50 weeks ) and the extent of the injury , as indicated by the magnetic resonance imaging parameters . Involvement of the proximal free tendon , as estimated by MRI , and proximity to the ischial tuberosity , as estimated both by palpation and magnetic resonance imaging , were associated with longer time to return to pre-injury level . Conclusion Careful palpation during the first 3 weeks after injury and magnetic resonance imaging investigation performed during the first 6 weeks after injury provide valuable information that can be used to predict the time to return to pre-injury level of performance in elite sprinting 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 Objectives : To undertake a detailed epidemiological study of training injuries sustained by professional rugby union players in order to define their incidence , nature , severity , and causes . Methods : A two season prospect i ve design was used to study training injuries associated with 502 rugby union players at 11 English Premiership clubs . Team clinicians reported all training injuries on a weekly basis and provided details of the location , diagnosis , severity , and mechanism of each injury . Training exposures for individual players were recorded on a weekly basis . Loss of time from training and match play was used as the definition of an injury . Results : The overall incidence of injury was 2.0 per 1000 player-hours , and each injury result ed on average in 24 days lost time . Recurrences , which accounted for 19 % of injuries , were more severe ( 35 days ) than new injuries ( 21 days ) . Twenty two per cent of all training occurred during the preseason but 34 % of all injuries were sustained in this period . Hamstring , calf , hip flexor/quadriceps , and adductor muscle injuries were the most common for backs , whereas hamstring , lateral ankle ligament , and lumbar disc/nerve root injuries predominated for forwards . Lumbar disc/nerve root , shoulder dislocation/instability , and hamstring muscle injuries for forwards and hamstring muscle and anterior cruciate ligament injuries for backs caused the greatest number of days absence . Running was the predominant cause of injury for both forwards and backs , although the overall incidence and severity of injuries sustained during skills training were significantly greater than those sustained during conditioning training . Conclusions : On average , a club will have 5 % of their players unavailable for selection as a consequence of training injuries The purpose of the present study was to examine the incidence rates of acute hamstring injuries in Danish elite football sustained during training or match play .  Furthermore , it was our intention to document details about the recurrence , severity and the injury seasonal distribution . Hamstring injuries among 374 elite football players were registered prospect ively during a 12-month period . A total of 46 first-time and eight recurrent hamstring injuries were registered . The incidence rates for incurring a first-time hamstring injury showed a significantly ( P<0.01 ) greater incidence rate per 1000 h during match play compared with training . Of 32 players who reported a hamstring injury in the 12-month period before the study , eight ( 25 % ) incurred an injury that fulfilled the criteria for a recurrent injury . In 69 % of the injuries , the severity of injury was categorized as moderate ( 8 - 28 days from injury to injury free ) and 18 % as severe ( > 28 days from injury to injury free ) . Each team sustained a mean of 3.4 hamstring injuries per season , with a mean of 21.5 days missed per injury ( range 3 - 136 ; median 16 days per injury ) . The seasonal distribution showed an accumulation of injuries in the first 2 months after a 3.5-month mid-season winter break Background Previous studies on the prognostic value of clinical and MRI parameters for the time to return to play ( TTRTP ) in acute hamstring injuries showed only limited to moderate evidence for the various investigated parameters . Some studies had multiple method ological limitations , including retrospective design s and the use of univariate analysis only . The aim of this study was to assess the prognostic value of clinical and MRI parameters for TTRTP using multivariate analysis . Methods 28 clinical and MRI parameters were prospect ively investigated for an association with TTRTP in 80 non-professional athletes with MRI positive hamstring injuries undergoing a st and ardised rehabilitation programme . The association between possible prognostic parameters and TTRTP was assessed with a multivariate linear regression model . Parameters that had a p value < 0.2 on univariate testing were included in this model . Results 74 athletes were available for analysis . A total of nine variables met the criteria for the multivariate analysis : intensity of sports , level of sports , self-predicted TTRTP by the athlete , length of discomfort on palpation , deficit in passive straight leg raise , pain score on isometric knee flexion , isometric knee flexion strength deficit and distance of the proximal pole of the MRI hyperintensity to the tuber ischiadicum . Of these , only self-predicted TTRTP by the athlete and a passive straight leg raise deficit remained significantly associated with TTRTP after stepwise logistic regression . Conclusions The clinical parameters self-predicted TTRTP and passive straight leg raise deficit are independently associated with the TTRTP . MRI parameters in grade 1 and 2 hamstring injuries , as described in the literature , are not associated with TTRTP . For clinical practice , prognosis of the TTRTP in these injuries should better be based on clinical parameters Objective To determine the incidence and characteristics of newly incurred injuries and illnesses during international Athletics Championships , by improving the medical surveillance coverage , in order to determine future prevention strategies . Design Prospect i ve recording of newly occurred injuries and illnesses . Setting 13th International Association of Athletics Federations World Championships in Athletics 2011 in Daegu , Korea . Participants National team and Local Organising Committee physicians ; and 1851 registered athletes . Main outcome measures Incidence and characteristics of newly incurred injuries and illnesses . Results 82 % of athletes were covered by medical teams participating with a response rate of 94 % . A total of 249 injuries were reported , representing an incidence of 134.5 injuries per 1000 registered athletes , and 119 ( 48 % ) result ed in time loss from sport . A total of 185 injuries affected the lower limb ( 74 % ) . Hamstring strain was the main diagnosis and 67 % result ed in absence from sport . Overuse ( n=148 ; 59 % ) was the predominant cause . A total of 126 illnesses were reported , signifying an incidence of 68.1 per 1000 registered athletes . Upper respiratory tract infection was the most common reported diagnosis ( 18 % ) , followed by exercise-induced dehydration ( 12 % ) , and gastroenteritis/diarrhoea ( 10 % ) . The highest incidences of injuries were found in combined events and middle and long-distance events , and of illness in race walking events . Conclusion During elite Athletics World Championships , 135 injuries , 60 time-loss injuries and 68 illnesses per 1000 registered athletes were reported . Higher risks of injuries were found in combined events and long-distance runs . Preventive interventions should focus on overuse injuries and hamstring strains , decreasing the risk of transmission of infectious diseases , appropriate event scheduling and heat acclimatisation Background Evidence suggests that to facilitate physical activity sedentary people may adhere to one component of exercise prescriptions ( intensity , duration or frequency ) without adhering to other components . Some experts have provided evidence for determinants of adherence to different components among healthy people . 
    Output:
    
The null-biased effect in using intent-to-treat methods from intervention non-compliance has a substantial impact on the precision , heterogeneity and the direction and strength of pooled estimates .
Eccentric strengthening , with good compliance , appears to be successful in prevention of hamstring injury