Isokinetic Muscle Strength Of Shoulder Joint And Surface Electromyography Characteristics In Different Sitting Positions

Objective:The isokinetic muscle performance and surface electromyography characteristics of shoulder joint were compared in different sitting positions,a theoretical basis and experimental basis for the study of body posture,prevention and treatment of musculoskeletal pain will be provided by exploring the performance characteristics of shoulder joints in different sitting positions.Methods:The CON-TREX isokinetic test system was used to test the peak torque,average power and total work of external rotator muscle groups and shoulder flexion and elbow flexor groups of male college students of the superior lateral shoulder joints under different sitting positions(upright,slumped,slouched).Results:(1)There was significant difference in the relative peak torque of the internal rotator groups and the external rotator groups during isokinetic eccentric exercise at 60°/s in three sitting positions(p<0.05),there was significant difference in the relative peak torque of the internal rotator groups and the external rotator groups during isokinetic concentric exerciese at 1200/s in three sitting positions(p<0.05);(2)There was significant difference in the average power,total work of the shoulder flexor muscle group and the total work of elbow flexor group during isokinetic concentric exercise at 60°/s of the shoulder joint in the three sitting positions(p<0.05);(3)There was significant difference in the contribution rate of upper trapezius and lower trapezius of shoulder joint during isokinetic internal rotation contraction movement in three sitting positions(p<0.05);(4)The muscle contribution rate of erector spinae in shoulder joint isokinetic elbow flexion exercise was statistically significant in three sitting positions(p<0.05),and the muscle contribution rate of anterior deltoid was statistically significant of elbow flexion during isokinetic concentric exercise at 60 °/s in the three sitting positions(p<0.05);(5)The IEMG values of the erector spinae,upper trapezius and lower trapezius were significantly different in the three sitting positions(p<0.05);(6)The IEMG values of the erector spinae,upper trapezius,lower trapezius and left rectus abdominis were significantly different in the three positions(p<0.05).Conclusion:.(1)The performance of shoulder joint under different sitting position is different.The isokinetic muscle strength of the upright sitting posture was better than that of the slouched sitting posture and slumped sitting positions;(2)Slouched sitting posture and slumped sitting posture will increase the trapezius,erector spine,rectus abdominis muscle activity,changing the movement pattern,leading to muscle compensation and shoulder joint instability,affecting the posture stability of the trunk.