***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: STUDY DESIGN A nonr and omized 2-group pretest-posttest design . OBJECTIVES To determine the effects of a 4-week balance training program during stance on a single leg . BACKGROUND Individuals who have experienced multiple episodes of inversion ankle sprains often participate in balance training programs . Balance training is performed to treat existing proprioceptive deficits and to restore ankle joint stability , presumably by retraining altered afferent neuromuscular pathways . The effectiveness of such programs on individuals with functionally unstable ankles has yet to be established . METHODS AND MEASURES Prior to and following training , subjects with self-reported functionally unstable ankles ( 5 women and 8 men , mean age = 21.9 + /- 3.1 years ) and nonimpaired subjects ( 6 women and 7 men , mean age = 21.2 + /- 2.5 years ) completed a  static balance assessment  for both limbs as well as the  ankle joint functional assessment tool question naire ( AJFAT ) . The subjects from both groups participated in a unilateral , multilevel , static and dynamic balance training program 3 times a week for 4 weeks . Subjects from the experimental group trained only the involved limb , and the nonimpaired group  trained a r and omly selected limb . A stability index ( SI ) was calculated during the balance assessment to indicate the amount of platform motion . Compared to low stability indices , high stability indices indicate greater platform motion during stance and therefore less stability . RESULTS Following training , subjects from both groups demonstrated significant improvements in balance ability . When balance was assessed at a low resistance to platform tilt ( stability level 2 ) , the posttraining scores of both the subjects with unstable ankles ( mean SI = 2.63 + /- 1.92 ) and the nonimpaired subjects ( mean SI = 2.69 + /- 2.32 ) were significantly better than their pretraining scores ( mean SIs = 5.93 + /- 3.65 and 4.67 + /- 3.43 , respectively ) . Assessed at a high resistance to platform tilt ( stability level 6 ) , the posttraining scores of both subjects with unstable ankles ( mean SI = 1.27 + /- 0.66 ) and the nonimpaired subjects ( mean SI = 1.37 + /- 0.66 ) were significantly better than their pretraining scores ( mean SIs = 2.30 + /- 1.88 and 2.04 + /- 1.43 , respectively ) . Additionally , the posttraining AJFAT scores of subjects with unstable ankles ( 25.78 + /- 3.80 ) and the nonimpaired subjects ( 29.15 + /- 5.27 ) were significantly greater than their pretraining scores ( 17.11 + /- 3.44 and 22.92 + /- 5.22 , respectively ) , indicating an overall improvement in perceived ankle joint functional stability . CONCLUSIONS This study suggests that balance training is an effective means of improving joint proprioception and single-leg st and ing ability in subjects with unstable and nonimpaired ankles UNLABELLED Despite the high incidence of chronic ankle instability ( CAI ) , the underlying neurophysiologic mechanism is unknown . Evidence suggests that both feed-forward and feedback mechanisms may play a role . However , no investigation has examined both control mechanisms during the same movement task in the same cohort of CAI patients . PURPOSE To determine the neuromuscular and biomechanical control alterations present in CAI patients during planned ( feed-forward ) and unplanned ( feedback ) gait termination . METHODS Twenty subjects with CAI and 20 uninjured controls completed planned and unplanned gait termination protocol s. Both tasks began with subjects walking at a self-selected speed across a 12-m walkway . Unplanned gait termination required subjects to stop during r and omly selected trials on two adjacent force plates when cued . Planned gait termination required purpose ful stopping on the force places . Propulsive and braking force magnitude and the dynamic postural stability index were calculated from the result ing ground reaction forces . In addition , muscle activity from the soleus , tibialis anterior , and gluteus medius was collected bilaterally . RESULTS Both maximum propulsive ( CAI = 99.8 + /- 40.8 N , control = 88.6 + /- 33.6 N ) and braking ( CAI = 207.1 + /- 80.9 N , control = 161.6 + /- 62.2 N ) forces were significantly higher in the CAI group . The dynamic postural stability index revealed higher scores in the CAI group ( 0.24 + /- 0.03 ) compared with the control group ( 0.22 + /- 0.03 ) . Muscle activation of the soleus and tibialis anterior differed during unplanned and planned gait termination between groups ( P < 0.05 ) and between the limbs of the CAI group ( P < 0.05 ) . CONCLUSIONS Altered biomechanical strategies during both planned and unplanned gait termination indicate that patients with CAI have alterations in feed-forward neuromuscular control and suggest the presence of feedback neuromuscular control deficits STUDY DESIGN Prospect i ve , r and omized controlled trial . OBJECTIVE To examine the effects of a 4-week rehabilitation program for chronic ankle instability ( CAI ) on postural control and lower extremity function . BACKGROUND CAI is associated with residual symptoms , performance deficits , and reinjury . Managing CAI is challenging and more evidence is needed to guide effective treatment . METHODS AND MEASURES Subjects with unilateral CAI were r and omly assigned to the rehabilitation ( CAI-rehab , n=16 ) or control ( CAI-control , n=13 ) group . Subjects without CAI were assigned to a healthy group ( n=19 ) . Baseline testing included the ( 1 ) center of pressure velocity ( COPV ) , ( 2 ) star excursion balance test ( SEBT ) , and ( 3 ) Foot and Ankle Disability index ( FADI ) and FADI-Sports Subscale ( FADI-Sport ) . The CAI-rehab group completed 4 weeks of rehabilitation that addressed range of motion , strength , neuromuscular control , and functional tasks . After 4 weeks , all subjects were retested . Nonparametric analyses for group differences and between-group comparisons were performed . RESULTS Subjects with CAI demonstrated deficits in postural control and SEBT reach tasks of the involved limb compared to the uninvolved limb and reported functional deficits of the involved limb compared to healthy subjects . Following rehabilitation , the CAI-rehab group had greater SEBT reach improvements on the involved limb than the other groups and greater improvements in FADi and FADI-Sport scores . CONCLUSIONS These results demonstrate postural control and functional limitations exist in individuals with CAl . In addition , rehabilitation appears to improve these functional limitations . Finally , there is evidence to suggest the SEBT may be a good functional measure to monitor change after rehabilitation for CAI Objective : To assess the capacity of the Biodex Stability System using a one-leg stance protocol to differentiate between injured and non-injured limbs and between level of disabilities . Design : Cross-sectional study . Setting : Military and civilian clinic . Subjects : Thirty-four individuals with a second-degree lateral ankle sprain and 36 healthy subjects . Methods and measures : Subjects were tested on the Stability System 30 days after injury using a one-leg stance protocol in the dynamic limit-of-stability mode . All subjects also filled out a disability question naire ( Lower Extremity Functional Scale ) . The groups were compared based on the overall dynamic limit-of-stability score and its relationship with the score on the disability question naire was also examined . Results : The overall dynamic limit-of-stability scores ( subjects with a lateral ankle sprain : 13.0 % (5.5)-26.0 % ( 9.2 ) ; healthy subjects : 16.9 % (7.9)-27.9 % ( 9.6 ) ) clustered in the lower end of the theoretical range of 0–100 % . Statistically significant differences in the overall dynamic limit-of-stability scores were found between the injured and non-injured limbs but group differences were small and clinical ly not relevant . No significant relationships were found between the overall dynamic limit-of-stability scores and the Lower Extremity Functional Scale scores ( 58.2 ( 11.8 ) ) of the subjects with a lateral ankle sprain . Conclusions : The one-leg stance protocol carried out in the dynamic limit-of-stability mode is very challenging and offers a very limited capacity to differentiate between injured and non-injured limbs . The main outcome of the Stability System does not appear to be a good indicator of the functional capacity of people with a lateral ankle sprain Objective : To examine the effectiveness of a sport-specific balance training program in reducing injury in adolescent basketball . Design : Cluster r and omized controlled trial . Setting : Twenty-five high schools in Calgary and surrounding area . Subjects : Nine hundred and twenty high school basketball players ( ages 12 - 18 ) . Intervention : Subjects were r and omly allocated by school to the  control ( n = 426 ) and training group ( n = 494 ) . Both groups were taught a st and ardized warm-up program . The training group was also taught an additional warm-up component and a home-based balance training program using a wobble board . Main Outcome Measures : All injuries occurring during basketball that required medical attention and /or caused a player to be removed from that current session and /or miss a subsequent session were then recorded and assessed by a team therapist who was blinded to training group allocation . Results : A basketball-specific balance training program was protective of acute-onset injuries in high school basketball [ RR = 0.71 ( 95 % CI ; 0.5 - 0.99 ) ] . The protective effect found with respect to all injury [ RR = 0.8 ( 95 % CI ; 0.57 - 1.11 ) ] , lower-extremity injury [ RR = 0.83 ( 95 % CI ; 0.57 - 1.19 ) ] , and ankle sprain injury [ RR = 0.71 ( 95 % CI ; 0.45 - 1.13 ) ] were not statistically significant . Self-reported compliance to the intended home-based training program was poor ( 298/494 or 60.3 % ) . Conclusions : A basketball-specific balance training program was effective in reducing acute-onset injuries in high school basketball . There was also a clinical ly relevant trend found with respect to the reduction of all , lower-extremity , and ankle sprain injury . Future research should include further development of neuromuscular prevention strategies in addition to further evaluation of methods to increase compliance to an injury-prevention training program in adolescents We studied prospect ively the influence of  ankle sprains  on proprioception as measured by recording the pos tural sway of classical ballet dancers . Excellent bal ance and coordination are important for classical ballet dancers , and postural stability requires adequate pro prioception from the ankle joint . Fifty-three professional dancers from the Royal Swedish Ballet , Stockholm , and 23 nonathletes , the control group , participated in the investigation .  Postural sway was recorded and an alyzed with a stabilimeter  using a specially design ed , portable , computer-assisted force plate .  Six dancers sustained ankle sprains during followup . The record ings were obtained of these dancers before and after the injuries . The stabilometry results differed among the male and female dancers and the control group as follows : 1 ) the male dancers demonstrated a smaller total area of sway , and 2 ) both the male and female dancers had a smaller mean sway on the left foot than on the right ( no mean difference in sway was found between the left and right foot in the control group ) . In comparison with the condition before injury and with the uninjured foot , the postural stability of the dancer was impaired for several weeks after the ankle sprain . Postural stability gradually improved during rehabilita tion and improvement still occured several weeks after professional dancing had resumed The aim of this study was to investigate  motor control  in subjects with functional instability of the ankle joint . This was achieved by analysing patterns of lower extremity motion prior to and immediately following l and ing during single leg jumping in subjects with functional instability of the ankle . Fourteen subjects with unilateral functional instability and 10 healthy control subjects performed single leg jumps from a 40 cm height whilst angular displacement of their ankle and knee joints were recorded . Subjects with functional instability demonstrated significantly greater ankle dorsiflexion over the period encompassing 10 ms pre l and ing to 20 ms post l and ing ( p < 0.05 ) . They also exhibited a significantly greater level of knee flexion than controls over the period from 20 ms pre l and ing to 60 ms post l and ing ( p < 0.05 ) . The timing of these significant differences leads us to conclude that they do not arise as a result of reflexively mediated peripheral events following l and ing OBJECTIVE To analyze risk factors , including postural sway , ankle strength , and flexibility , for the prediction of ankle injuries in men 's high school basketball players . DESIGN A cohort study with follow-up duration of 1 basketball season . SETTING Biomechanics laboratory . PARTICIPANTS Forty-two ( age , 16.5+/-1.1y ) players competing in first league of the High School Basketball Association without history of injury in the lower extremities within 6 months before recruitment and without significant malalignment in the lower extremities were included . None of these players met exclusion criteria such as using ankle braces or taping or failed in wearing low-top sports shoes during the follow-up season . INTERVENTIONS Not 
    Output:
    
These findings provide strong evidence that balance is bilaterally impaired after an acute lateral ankle sprain .
However , these findings suggest that bilateral balance deficits are not present in patients with chronic ankle instability .
Further , patients with acute lateral ankle sprains should undergo balance training on both limbs