Development Of The Lower Extremity Functional Test (LEFT) Tool For Sports Injury Prevention: An Application Research

ObjectiveWith the promotion of the concept of the integration of sports and medicine,the number of the population participating in sports in China is increasing year by year.Epidemiological studies have reported that the risk of injury in people who regularly participate in various sports activities is 1.5-2.0 times that of inactive people,and the lower quadrant injuries are the most common musculoskeletal injuries in various sports.As a means to identify injury risk and guide the implementation of a training plan to prevent sports injury,movement screening has been widely used in the field of sports rehabilitation and physical training.In this study,a systematic review of existing movement screening tools was conducted,and it was found that the predictive value of these movement screening tools was limited and did not support their widespread application.Therefore,it is necessary to develop a novel movement screening tool to predict the risk of LQ injury,and to develop targeted training programs,to effectively reduce the risk of LQ injury.As such,this study has three purposes:（1）to develop a novel movement screening tool aimed at predicting the risk of LQ injury,that is,the Lower Extremity Functional Test（LEFT）;（2）Test the reliability and validity of LEFT,identify the risk factors of LQ injury through the outcomes,and guide the development of targeted training programs;（3）To test whether the targeted training can effectively reduce the risk of LQ injury.MethodsThe research content is divided into three parts.The first part is design and development LEFT.Based on the previous movement screening tools,the theoretical framework of LEFT research and development was determined,and the LEFT motion base to be selected was proposed.Through the method of domestic and foreign experts’discussion,the LEFT movement was screened and determined,and the quality of LEFT movement and symptom scoring criteria were formulated.The second part systematically tested the reliability and validity of LEFT through four studies（study 1,2,3,and 4）.The first study used 3 raters to repeat the test and score 20 subjects with an interval of 7 days.Analysis of ANOVA and intraclass correlation coefficient（ICC）was conducted to analyze inter-rater reliability,intra-rater reliability,and intra-tester reliability of LEFT.The second was used for the discriminative validity test.A retrospective cohort study was used to conduct the LEFT test on 225 healthy and active subjects and investigate the injury conditions in the 12 months before the test,to explore whether LEFT score could distinguish subjects with and without LQ injury history.The third study was a predictive validity test.A prospective cohort study was used to perform the LEFT test on 76 healthy and active participants,and they were followed up for 12 months to record LQ injury.To explore whether the LEFT test could effectively predict the risk of LQ injury,and to establish a regression equation to predict the risk of injury.The fourth study was a content validity test.A cross-sectional study method was adopted to test LEFT,balance,muscle strength,and flexibility on 28 participants to explore the relationship between the results of the LEFT and the above independent risk factors.In the third part（study 5）,according to the relationship between the outcomes of the five individual movements of the LEFT and independent risk factors in the fourth study,a three-dimensional wind vane of body function was put forward,based on which targeted training programs were formulated.To explore the effect of targeted training on the risk of LQ sports injury.The 75 participants were divided into three groups:targeted training intervention group（group I,n=25）,routine physical training control group（group C1,n=25）,and non-exercise control group（group C0,n=25）.Group I received targeted training for 8 weeks,group C1 received routine physical training for 8 weeks,and group C0 only received injury prevention education.Outcomes of the LEFT test and injury risk of subjects in the three groups were compared before and after the interventions.ResultsIn the first part,a novel movement screening LEFT is designed and developed.This test was a battery of five weight-bearing functional movements involving different movement planes,directions,modes,and at varying intensities.It includes structural and functional tests.The test results include Movement Quality（MQ）and Symptom Score（SS）.In the second part,the results of ANOVA of the first study showed that there was no significant difference between the scores of different raters（F=0.353;p=0.705）,between two video ratings of the same rater（F=0.708,p=0.404）and twice LEFT test of the participants（F=0.156;p=0.679）were not statistically significant.ICC showed that LEFT had excellent inter-rater reliability ICC_2,3=0.949,（95%CI:0.893-0.978）,intra-rater reliability ICC_2,3=0.953,（95%CI:0.921-0.972）and intra-tester reliability ICC_2,1=0.875,（95%CI:0.712-0.949）.Results of the second study showed that the MQ（z=-5.387,p<0.001）and SS（z=-3.990,p<0.001）of group with a history of LQ injury were significantly lower than those without LQ injury history.Binary logistic regression analysis showed that both MQ（OR=0.937,p<0.001）and SS（OR=0.935,p<0.001）were correlated with LQ injury history（adjusted R2=0.241）.When MQ was used to distinguish the history of LQ injury,the AUC under the subject characteristic curve was 0.720（p<0.001,95%CI:0.652-0.787）,and when SS was used to distinguish the history of LQ injury,the AUC was 0.656（p<0.001,95%CI:0.576-0.736）.When combined with MQ and SS,the AUC was 0.763（p<0.001,95%CI:0.699-0.826）,indicating that 76.3%of cases could be accurately distinguished.Results showed that the MQ（Z=-3.489,p<0.001）and SS（Z=-3.504,p<0.001）of participants with LQ injury were significantly lower than those without LQ injury.Binary logistic regression analysis showed that both MQ（OR=0.916,p=0.004）and SS（OR=0.919,p=0.003）of LEFT test results were correlated with LQ injury and could be used as independent predictors of LQ injury risk.R2=0.312（adjusted R2=0.453）.The regression equation was established according to binary logistic regression analysis:P=1/1+e^{-（12.142-0.088MQ-0.085SS）}.When MQ was used to predict LQ injury,the AUC was0.772（p<0.001,95%CI:0.653-0.891）,and when SS was used to predict LQ injury,the AUC was 0.771（p=0.001,95%CI:0.638-0.905）.When MQ and SS were used together,AUC=0.853（p<0.001,95%CI:0.754-0.953）,indicating that 85.3%of cases could be accurately predicted.Results of the fourth study showed that,in the correlation analysis between LEFT and balance,MQ of LEFT test was significantly correlated with SOT indexes ES（rho=0.456,p=0.013）,BS（rho=0.510,p=0.006）and COMP（rho=0.441,p=0.019）.MQ and LOS test indexes RT-RA（rho=-0.375,p=0.049）,EPE-A（rho=0.413,p=0.029）,EPE-RA（rho=0.439,p=0.020）,EPE-R（rho=0.399,p=0.036）,EPE-LA（rho=0.495,p=0.007）,MXE-A（rho=0.611,p=0.001）,MXE-R（rho=0.423,p=0.025）,MXE-LA（rho=0.425,p=0.024）were significantly correlated;MQ was significantly correlated with one-leg balance during eye-opening（rho=-0.475,p=0.011）.SS of LEFT test was significantly correlated with RT-RA（rho=-0.436,p=0.020）,EPE-RA（rho=0.519,p=0.002）and MXE-P（rho=0.446,p=0.017）.In the correlation analysis between LEFT and isokinetic muscle force,MQ was significantly correlated with the relative peak torque of knee flexor（Rho=0.526,p=0.004）.In the correlation analysis between LEFT and lower extremity flexibility,SS was significantly correlated with the flexibility of quadriceps femoris（rho=0.434,p=0.024）and iliopsoas（rho=-0.445,p=0.020）.In the correlation analysis of LEFT single action and balance,LEFT test index MQ1 was significantly correlated with SOT indexes ES（rho=0.383,p=0.044）,BS（rho=0.408,p=0.011）and COMP（rho=0.403,P=0.034）.MQ2 was significantly correlated with SOT indices ES（rho=0.517,p=0.005）,BS（rho=0.472,p=0.011）and COMP（rho=0.469,p=0.012）.MQ3 was significantly correlated with SOT indices ES（rho=0.412,p=0.029）,BS（rho=0.439,p=0.019）and COMP（rho=0.417,p=0.027）.MQ4 was significantly correlated with LOS index MEX（rho=0.552,p=0.004）.MQ1 was significantly correlated with one-leg balance in open eyes（rho=-0.400,p=0.035）and closed eyes（rho=-0.418,p=0.027）.In the correlation analysis of LEFT single movement and isotropic muscle strength,MQ3 was significantly correlated with the relative peak torque of the knee extensor（Rho=0.525,p=0.004）.MQ4 was significantly correlated with the relative peak torque of knee extensor（rho=0.490,P=0.008）and flexor（rho=0.593,p=0.003）.In the correlation analysis between LEFT single movement and flexibility,MQ4（rho=0.524,p=0.005）and MQ5（rho=0.395,p=0.042）were significantly correlated with quadriceps femoris flexibility.SS1 was significantly correlated with the flexibility of iliopsoas muscle（rho=-0.407,p=0.035）and quadriceps femoris muscle（rho=0.426,p=0.027）,SS3 was significantly correlated with the flexibility of iliopsoas muscle（rho=-0.394,p=0.042）,SS5 was significantly correlated with the flexibility of iliopsoas muscle（rho=-0.468,p=0.038）and quadriceps femoris muscle（rho=0.416,p=0.031）.In the third part,the results of trial 5 showed that there were no significant differences in MQ（p=0.597）,SS（p=0.084）,LQ injury risk（χ2=0.750,p=0.687）,and LQ injury rate（χ2=0.120,p=0.942）among the three groups before intervention.Intervention period and intervention means had a significant influence on MQ（p=0.040）.After the intervention,at week 4,MQ was significantly higher in group I（p<0.001）than at baseline,while there was no significant change in C1（p=0.957）or C0（p=0.113）.At 8 weeks,MQ was significantly higher in group I（p<0.001）than at baseline,while there was no significant change in C1（p=0.776）or C0（p=0.410）.Intervention period and intervention means had no significant effect on SS（p=0.218）.There was no significant change in SS of group I,C1,and C0 during the intervention period.After the intervention,the risk of LQ injury in group I（χ2=8.333,p=0.016）was significantly decreased,while the risk of LQ injury in group C1（χ2=1.042,p=0.594）and group C0（χ2=0.753,p=0.686）had no significant change.Conclusion（1）LEFT is the first functional screening tool for the targeted prediction of LQ injury risk.The proposed theoretical framework and the joint evaluation of movement quality and symptoms can provide a useful reference for the future development of movement screening for other parts or the improvement of the existing movement screening.（2）LEFT is a reliable,and effective screening tool for the risk of LQ sports injury,which can accurately distinguish whether there is a history of LQ injury,and can predict the risk of LQ sports injury through the established regression equation;LEFT had good content validity.Every single action of LEFT is correlated with these risk factors respectively,which can be used as the basis for formulating targeted training.（3）Combining MQ and SS can improve the discriminant validity and prediction validity.（4）Targeted training designed according to the results of the LEFT test can improve MQ and effectively reduce the risk of LQ injury;Routine physical training and education did not reduce LQ injury risk.Targeted training,routine physical training,and education did not change SS.Therefore,other intervention methods other than exercise intervention should be considered for people with related symptoms.