| Upper Limb Whiplash Movement is the main skill of many sports, due to the same movements frequently repeated, damage easily happened, so that the shoulder dynamic stability will be destroyed. Previous studies suggest that, to improve the weakness of centripetal force of antagonistic muscle group can improve the stability of the shoulder; Recent research suggests that, the effect is more obvious according centrifugal stability control practice to improve the shoulder stability, and even this practice may improve arm speed.Subject:The aim of the study was to discuss if the isokinetic eccentric strength training to the antagonist muscles of internal rotation movement will improve the joint motion, muscle strength and coordination, and especially to observe if eccentric antagonise/concentric agonist peak toque ratios in the process of internal rotation movement will be change. Whether these changes will help to enhance the dynamic stability of the shoulder joint in the process of spiking, then in order to achieve the purpose of improving arm speed.Methods:Select 21 professional volleyball athletes(level 2 or above) without obvious symptoms of shoulder joint injury within the past half of year. Random allocation was taken to averagely divide them into three groups,7 athletes/group, respectively:group 1 (S1)was working in isokinetic concentric strength training of internal rotation muscles; group 2(S2) was isokinetic eccentric strength training of external rotation muscles;group 3 (S3) was isokinetic concentric strength training of internal rotation muscles combined with isokinetic eccentric strength training of external rotation muscles. Training for 6 weeks,3 times a week; Every time 6 groups, repeat 8/group, group of rest between 1-2 min. Training before and after the intervention, the testing methods and evaluation indexes include:1 Shoulder joint mobility and flexibility test; 2 Muscle strength test:isometric maximum strength, isokinetic peak torque, and the torque and speed of isotonic testing; 3 High-speed video test:the arm terminal speed, the ball speed, etc.Results:After the training,1 Shoulder motion, right shoulder in S1 and S3 group increased significantly (P< 0.05) and S3 was very much(P< 0.01), but group 2 had no difference; the external rotation angle of group S3 was very significantly incresed (P< 0.01).2 Shoulder flexibility, the indexs were no significant difference (P> 0.05), the distance of S1 and S3 when the righ hand above was slightly reduced, but S2 group increased. 3 Isometric maximum strength, the strength of internal rotantion muscle in S1 and S2 group increased significantly (P< 0.05), S1 group was very much(P< 0.01); the strength of external rotation muscles in S2 group increased significantly(P< 0.05).4 The isokinetic test:concentric peak toque of internal rotation muscles in S1 group significantly increased (P< 0.05); eccentric peak toque of external rotation muscles in S2, S3 group increased significantly (P< 0.05), S2 groups was very significant (P< 0.01), and external rotation muscles ECC/internal rotation muscles CON peak toque ratio is significantly increased (P< 0.05); 5 Isotonic test:the power and arm speed of S1 group increased significantly (P< 0.05) when internal rotation movement, and the arm speed of S2 group increased significantly (P< 0.05) when simulating spiking in sitting posture.6 The sport ability (that is arm terminal speed and the ball speed) in three groups, did not significantly change (P> 0.05).Conclusion:1 The isokinetic eccentric strength training to the antagonist muscles of internal rotation movement had improved the active external motion of shoulder; 2 The training had improved the balance of shoulder rotation muscle group, developed the external rotation muscles with centrifugal control ability, and enhanced the dynamic stability of the shoulder joint; 3 The training had increased arm speed when when simulating spiking in sitting posture, but had no significant influence to the actual arm speed. |
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