Effects Of Whole-body Fatigue On Balance And Ankle Proprioception During Drop Landing Among Individuals With And Without Chronic Ankle Instability

Objective:The purpose of this study was to compare chronic ankle instability(CAI)patients with healthy individuals before and after whole-body fatigue with changes in static balance,dynamic balance,and ankle proprioception during drop landing.To explore the effects of whole-body fatigue factor on balance and ankle proprioception of the two groups of participants,analyze the causes of recurrent ankle sprains in CAI patients,and provide data support for the prevention and rehabilitation of ankle sprains in CAI patients.Methods:A total of 31 participants with unilateral CAI and 31 healthy participants participated in this study.The whole-body fatigue protocol is to repeat the cycle of 10×6 m turn back run and vertical jump.A static balance test,dynamic balance test,and ankle proprioception test during drop landing were conducted before and after fatigue.The participants’ static balance was tested using a three-dimensional force platform,and the sway distance of the center of pressure(COP)in X-axis direction(D-x),sway distance of the COP in Y-axis direction(D-y),root mean square of the COP(RMS),RMS in the anteriorposterior(AP)direction(RMS-ap),RMS in the medialelateral(ML)direction(RMS-ml),total excursions(TOTEX),total excursions-AP(TOTEX-ap),total excursions-ML(TOTEX-ml),mean velocity(MVELO),mean velocity-AP(MVELO-ap),mean velocity-ML(MVELO-ml)and 95% confidence ellipse area of the COP movements(95% AREA)were calculated.The participants’ dynamic balance was tested using the YBalance test(YBT),and the normalise reach distance in the anterior(ANT),posteromedial(PM),and posterolateral(PL)directions was calculated.The ankle inversion discrimination apparatus for landing(AIDAL)was used to test the participants’ ankle proprioception during drop landing,and the ROC curve was generated and the AUC was calculated.Results:1.Static balance test resultsAfter whole-body fatigue,participants in the CAI group and control group showed a significant increase in all static balance index values(P<0.001)compared to before fatigue under four conditions: eye opening on stable plane,eye closing on stable plane,eye opening on unstable plane and eye closing on unstable plane.And in the CAI group,the difference in the D-x,D-y,RMS,RMS-ml,RMS-ap,TOTEX,TOTEX-ap,MVELO,MVELO-ap with eyes open under stable plane conditions,D-x,D-y,RMS,RMS-ml,RMS-ap,95% AREA,TOTEX,TOTEX-ap,MVELO,MVELO-ap with eyes closed under stable plane conditions,D-x,RMS,RMS-ml with eyes open under unstable plane conditions,and D-x,D-y,RMS-ml with eyes closed under unstable plane conditions(P <0.05 for each of these indices)before and after whole-body fatigue was significantly greater than that in the control group.2.Dynamic balance test resultsAfter whole-body fatigue,the normalise reach distance in the ANT,PM,and PL directions(P < 0.05 for each of these indices)in the CAI group and the healthy control group were significantly reduced compared to before fatigue induction;The difference of the normalise reach distance in the PM(P=0.036)and PL(P=0.015)directions in the CAI group before and after whole-body fatigue was significantly greater than that in the control group.3.Ankle proprioception test results during drop landingAfter whole-body fatigue,the AUC value(P < 0.001)of CAI group and control group was significantly decreased compared with that before fatigue induction.The difference of AUC before and after whole-body fatigue in the CAI group(P < 0.001)was significantly greater than that in the control group.Conclusion:The static balance,dynamic balance and ankle proprioception decreased in CAI patients and healthy individuals after whole-body fatigue,and the degree of decline in static balance,dynamic balance and ankle proprioception in CAI patients was significantly greater than that in healthy individuals,which may lead to increased risk of ankle sprain repeatedly.