Differences In Muscle Activities Of The Scapular Muscles In Open Kinetic Chain And Closed Kinetic Chain Exercises

Objectives:The coordinated contraction of the scapular muscles is the focus of shoulder rehabilitation.In recent years,the chain exercise of the shoulder has gradually attracted attention.Therefore,this study analyzes and compares the activation of the muscles around the middle scapula between the healthy people and the SD in the open and closed chain movements.Explored the advantages and disadvantages of the two types of exercise on the activation pattern of the scapula muscles,and clarified the optimal selection strategy for the rehabilitation of the shoulder joint injury.Methods:Forty-two subjects were divided into experimental group(22 patients)and control group(20 patients)according to the presence or absence of SD.Surface electromyography was used to obtain the corresponding data of the target muscle target movement,except for the experimental measurement of MVIC.Eight movements were selected for testing: open chain flexion,closed chain flexion,open chain extension,closed chain extension,open chain shoulder neutral external rotation,open chain shoulder abduction 90° external rotation,closed chain shoulder neutral externally rotated,and the closed shoulder abduction 90° external rotation.And calculate the relative integral myoelectricity and input percentage of the target muscle.Results:The comparison between the experimental group and the control group(1)in the shoulder abduction 90° position,the experimental group LSST difference was significantly higher than the control group,P <0.05.(2)Under the OKC,the activation of MT,LT and SA was better in the control group,and the activation of UT and PD was higher in the experimental group.In general,the control group of the scapular muscle group was better than the experimental group.(3)Under the CKC,the activation of the experimental group was optimized.The SA-iEMG%,LT-IEMG% and IS-input% of the shoulder joint flexion were higher than the control group,and the shoulder joint abduction was 90°.In the external rotation of the chain,the experimental group LT-iEMG% and input% were higher than the control group.The results of the opening and closing chain movements in the group are as follows:(1)The iEMG% and input% of the UT under the closed-chain buckling motion are significantly lower than the open-chain buckling.The iEMG% and input% of the SA in the experimental group are significantly higher than the open-chain buckling action.(2)The contraction degree of MT,LT and SA in the two groups was higher than that in the open chain,and the LT-input% was significantly higher than the open chain extension.(3)Under the external rotation of the shoulder joints,the iEMG% and input% of the two groups of UT,MT and LT are larger under the 90° open chain and the 0° closed chain,and the SA is the largest at the 90° open chain.However,the input% is the largest at 90° closed chain,and the iEMG% of IS and PD is the largest at 0° closed chain,but the input% of IS is the largest at 90° closed chain.Conclusions :(1)Differentchains of flexion have no differential effect on the contraction of the scapular muscles of healthy people.(2)Under the closed-chain exercise,the contraction between the scapula and the muscles of the SD is more optimized.It is suggested that the closed-chain training can be safely applied to the early stage of the shoulder injury patients Rehabilitation.(3)The closed chain extension is conducive to the contraction of MT,LT,and SA,and is more targeted for the mobilization of LT.(4)Closed-chain shoulder abduction 90° position external rotation exercise can safely and effectively activate the infraspinatus muscle,which is the best action of external rotation of the shoulder joint,and is more suitable for early rehabilitation of the rotator cuff injury involving the IS.In the use of 0 ° open chain action can also obtain a larger activation ratio,it is recommended to apply in the middle and late rehabilitation of the shoulder joint has a stable foundation.