LAIC Research Based On Principal Component Analysis And Cluster Analysis

Purpose:This study is focused on a multi-muscle chain “LAIC” in the theory of a new physical therapy “Postural Restoration”.The purpose of this study is to identify whether this multi-muscle chain exist to make sure if this part of the basic concept of Postural Restoration is evidence-based.Method:Five subjects(badminton athlete in Chengdu Sports University)participated to execute three motor tasks subjected to COG(Center Of Gravity)shifting to the right:COG shifting right and forward,straight to the right,right and backward.Using Noraxon Telemyo2400DTS08 the electromyographic activity of 6 postural muscles(vastus medialis,rectus femoris,vastus lateralis,biceps femoris,gluteus maximus and tensor fasciae latae)were integrated over a 100 ms interval after the first COG shift.This shift was presented by the earliest shift of momentum shift which was detected by Kistler force platform.The subjects perform 30 trials in each task.Rest periods between trials and task were taken into consideration to avoid the influence of fatigue.Results:The integrated EMG activity was subjected to principal component analysis(PCA)across multiple repetitions of each task.Cluster analysis of the PC vectors across tasks and subjects were then considered.Data processing was run on SPSS 19.0.15 PCA were performed and the results shows that three PC were extracted which explained on average 85.5% of the varation.This study took the first two PC into further analysis.In 15 PCA,vastus medialis and vastus lateralis acted as significantly loaded muscles in the first PC for 12 times,9 times for rectus femoris.Gluteus maximus and tensor fasciae latae acted as significantly loaded muscles in the second PC for 9 and 6 times.According to previous study and functional anatomy theory,vastus medialis,vastus lateralis and rectus femoris in the first PC were identified as “extension and start”mode.Gluteus maximus and tensor fasciae latae in the second PC were identified as “closed chain abduction”mode.Biceps femoris was not included in any of these modes.The results are inconsistent with the concept of LAIC.Conclusion:COP shifting to the right is not controlled only by some muscles of LAIC but also controlled by two muscle chain that perform different functions.The concept of LAIC is faulty and needs to be improved.