***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 Purpose The objective of the present r and omised controlled trial was to study the effect of a neuromuscular warm-up programme on performance tests in youth female football . Methods Four youth female football teams with players aged 12–16 years were r and omised into an intervention group and control group . The intervention was a 15-min neuromuscular warm-up programme carried out twice a week during the 11-week study period . Baseline and follow-up measurements of performance were made indoors and included the star excursion balance test , a countermovement jump test , a triple-hop for distance test , a modified Illinois agility test , and 10- and 20-m sprint tests . Results Fifty-two players ( intervention 28 ; control 24 ) took part in baseline measurements , and after dropout , 41 players ( intervention 23 ; control 18 ) were included for analysis . Minor positive changes were seen in the control group compared to the intervention group for a sub-score of the star excursion balance test ( P < 0.05 ) and in the modified Illinois agility test ( P < 0.05 ) . No improvement was seen in the intervention group from baseline to follow-up . Conclusions The study showed that a neuromuscular warm-up programme carried out during 11 weeks did not improve performance in youth female football . This could indicate that the programme does not contain sufficient stimulus to improve performance . A low player attendance at training sessions , and low specificity between exercises in the warm-up programme and the evaluated performance tests may also contribute to the lack of effect . Level of evidence OBJECTIVE To determine the predictive validity of perceived risk , risk taking , estimation of ability , overefficacy , and previous injuries on actual injury among adolescents in sport ; and to examine sex differences on these factors . METHODS A cohort of 260 ( 148 male , 112 female ) soccer players aged 11 to 14 years participated in a 3-month prospect i ve injury study . Preseason written measures included self-reported perceived risk , previous injuries , risk taking and estimation of ability . RESULTS Low levels of perceived risk and estimation of ability were associated with a significant increase in risk of injury , with odds ratios ( ORs ) ranging from 3.77 - 7.92 . Positive relationships between injury and both estimation of ability and overestimation of ability were supported . Estimation of ability was also positively related to risk taking . In this study , however , risk taking was not directly related to injury , nor were previous injuries . Girls reported higher levels of perceived risk and lower levels of risk taking than boys . However , boys and girls reported similar estimation of ability and overestimation of ability and subsequently incurred similar numbers of injuries . CONCLUSIONS Perceived risk and estimation of ability represent significant psychological risk factors for injury in adolescent sports . Sex differences in perceived risk , risk taking , and previous injuries should be considered when developing environmental and behavioral injury-prevention programs PURPOSE The aim of this study was to investigate the segmental coordination of vertical jumps under fatigue . METHODS Twelve subjects performed maximal countermovement jumps with and without fatigue  , which was imposed by maximal continuous jumps in place until their maximal jump height corresponded to 70 % of the nonfatigued condition .  Video , ground reaction forces , and electromyographic signals were recorded to analyze the segmental coordination of countermovement jumps before ( CMJ1 ) and after ( CMJ2 ) fatigue . The magnitude of joint extension initiation , peak joint angular velocity , and peak net power around the ankle , knee , and hip joints and their respective times were determined . RESULTS CMJ2 was characterized by a longer contact time , which was accompanied with an earlier movement initiation and several differences ( P < 0.05 ) in the variables used to describe coordination . When the movement duration was normalized with respect to the contact phase duration , the differences between CMJ1 and CMJ2 were not sustained . A consistent pattern was indicated , in which the segmental coordination did not differ between jump conditions . When the magnitude of the muscle activation was set aside , a remarkably consistent muscle activation time was noticed between conditions . CONCLUSIONS It was indicated that countermovement jumps were performed with a consistent well-timed motion of the segments . A " common drive , " which acts without the knowledge of the muscle properties , was suggested as mediating and controlling the muscle activation timing between agonist-antagonist muscle pairs DiStefano , LJ , Padua , DA , Blackburn , JT , Garrett , WE , Guskiewicz , KM , and Marshall , SW . Integrated injury prevention program improves balance and vertical jump height  in children . J Strength Cond Res 24(2 ) : 332 - 342 , 2010-Implementing an injury prevention program to athletes under age 12 years may reduce injury rates . There is limited knowledge regarding whether these young athletes will be able to modify balance and performance measures after completing a traditional program that has been effective with older athletes or whether they require a specialized program for their age . The purpose of this study was to compare the effects of a pediatric program , which was design ed specifically for young athletes , and a traditional program with no program in the ability to change balance and performance measures in youth athletes . We used a cluster-r and omized controlled trial to evaluate the effects of the programs before and after a 9-week intervention period . Sixty-five youth soccer athletes ( males : n = 37 mass = 34.16 ± 5.36 kg , height = 143.07 ± 6.27 cm , age = 10 ± 1 yr ; females : n = 28 mass = 33.82 ± 5.37 kg , height = 141.02 ± 6.59 cm ) volunteered to participate and attended 2 testing sessions in a research laboratory . Teams were cluster-r and omized to either a pediatric or traditional injury prevention program or a control group . Change scores for anterior-posterior and medial-lateral time-to-stabilization measures and maximum vertical jump height and power were calculated from pretest and post-test sessions . Contrary with our original hypotheses , the traditional program result ed in positive changes , whereas the pediatric program did not result in any improvements . Anterior-posterior time-to-stabilization decreased after the traditional program ( mean change ± SD = −0.92 ± 0.49 s ) compared with the control group ( −0.49 ± 0.59 s ) ( p = 0.003 ) . The traditional program also increased vertical jump height ( 1.70 ± 2.80 cm ) compared with the control group ( 0.20 ± 0.20 cm ) ( p = 0.04 ) . There were no significant differences between control and pediatric programs . Youth athletes can improve balance ability and vertical jump height after completing an injury prevention program . Training specificity appears to affect improvements and should be considered with future program design Background and Purpose : Reduced feedback during motor skill practice benefits motor learning . However , it is unknown whether these findings can be applied to motor learning in children , given that children have different information-processing capabilities than adults . The purpose of this study was to determine the effect of different relative frequencies of feedback on skill acquisition in children compared with young adults . Subjects : The participants were 20 young adults and 20 children . Methods : All participants practice d 200 trials of a discrete arm movement with specific spatiotemporal parameters . Participants from each group ( adults and children ) were r and omly assigned to either a 100 % feedback group or a reduced ( 62 % faded ) feedback group . Learning was inferred from the performance on the delayed ( 24-hour ) retention and reacquisition tests . Results : All participants improved accuracy and consistency across practice trials . During practice , the adults performed with significantly less error than the children . Adults who practice d with reduced feedback performed with increased consistency during the retention test compared with those who practice d with 100 % feedback . In contrast , children who received reduced feedback during practice performed with less accuracy and consistency during the retention test than those who received 100 % feedback . However , when feedback was reintroduced during the reacquisition test , the children in the reduced feedback group were able to improve their performance comparable to those in the 100 % feedback group . Discussion and Conclusions : During motor learning , children use feedback in a manner different from that of adults . To optimize motor learning , children may require longer periods of practice , with feedback reduced more gradually , compared with young adults STUDY DESIGN Controlled cohort repeated- measures experimental design . OBJECTIVES To determine if a neuromuscular training program ( NMTP ) focused on core stability and lower extremity strength would affect performance on the star excursion balance test ( SEBT ) . We hypothesized that NMTP would improve SEBT performance in the experimental group and there would be no side-to-side differences in either group . BACKGROUND The SEBT is a functional screening tool that is used to assess dynamic stability , monitor rehabilitation progress , assess deficits following an injury , and identify athletes at high risk for lower extremity injury . The SEBT requires lower extremity coordination , balance , flexibility , and strength . METHODS Twenty uninjured female soccer players ( 13 experimental , 7 control ) participated . Players trained together as a team , so group allocation was not r and omized . The SEBT was administered prior to and following 8 weeks of NMTP in the experimental group and 8 weeks of no NMTP in the control group . A 3-way mixed-model ANOVA was used to determine the effect of group ( experimental versus control ) , training ( pretraining versus posttraining ) , and limb ( right versus left ) . RESULTS After participation in a NMTP , subjects demonstrated a significant improvement in the SEBT composite score ( mean ± SD ) on the right limb ( pretraining , 96.4 % ± 11.7 % ; posttraining , 104.6 % ± 6.1 % ; P = .03 ) and the left limb ( pretraining , 96.9 % ± 10.1 % ; posttraining , 103.4 % ± 8.0 % ; P = .04 ) . The control group had no change on the SEBT composite score for the right ( pretraining , 95.7 % ± 5.2 % ; posttraining , 94.4 % ± 5.2 % ; P = .15 ) or the left ( 97.4 % ± 7.2 % ; 93.6 % ± 5.0 % ; P = .09 ) limb . Further analysis identified significant improvement for the SEBT in the posterolateral direction on both the right ( P = .008 ) and left ( P = .040 ) limb and the posteromedial direction of the left limb ( P = .028 ) in the experimental group . CONCLUSION Female soccer players demonstrated an improved performance on the SEBT after NMTP that focused on core stability and lower extremity strength BACKGROUND CONTEXT A variety of self-report and physical performance-based outcome measures are commonly used to assess progress and recovery in the lower leg , ankle , and foot . A requisite attribute of any outcome measure is its ability to detect change in a condition , a construct known as " responsiveness " . There is a lack of consistency in how responsiveness is defined in all outcome measures . PURPOSE The purpose of this study was to review the currently used recovery outcome measures for lower leg , ankle and foot conditions in order to determine and report recommended responsiveness values . METHODS A systematic literature search that included electronic search es of PubMed , CINAHL and SportD iscus as well extensive cross-referencing was performed in January , 2013 . Studies were included if each involved : 1 ) a prospect i ve , longitudinal study of any design ; 2 ) any condition associated with the lower leg , ankle or foot ; 3 ) a measure of responsiveness ; and 4 ) was an acceptable type of outcome measure ( eg . self-report , physical performance , or clinician report ) . The quality of the included articles was assessed by two independent authors using the responsiveness sub-component of the Consensus-based St and ards for the selection of health Measurement Instruments ( COSMIN ) . RESULTS Sixteen different studies met the inclusion criteria for this systematic review . The most commonly used outcome measures 
    Output:
    
Endurance was not significantly affected by any of the programs .
Conclusion : This systematic review shows that injury prevention programs improve several modifiable intrinsic risk factors of lower extremity performance among youth athletes , particularly force generation .
However , several intrinsic risk factors were either not significantly affected or specifically addressed by existing programs