The Effect Of Change Of Hamstring And Quadriceps Femoris Strength Of Joint Of Knee On Shuttle Run

Purpose: As a special form of the changing direction running, shuttle run is common in training and actual movement in which knee muscle strength has great impact on. With the method of biomechanics, we try to find the change regulation of movement structures during the shuttle run before and after training of Hamstring and Quadriceps Femoris Strength of Joint of Knee in order to find out internal relation between the changes of knee muscle strength and shuttle run, and hence to provide theoretical guidance for sports training.Methods: Randomly set twenty-four non-sports professional students into 4 groups including flexion to extension group, always flexion group, extension to flexion group and always extension group respectively with twelve weeks exercising. Specifically, first six weeks flexor training and then six weeks extensor training for flexion to extension group, twelve weeks flexor training for always flexion group, first six weeks extensor training and then six weeks flexor exercise for extension to flexion group, and twelve weeks extensor training for always extension group. Before training and in the end of six weeks and twelve weeks, use Multi-joint isokinetic muscle strength measurement and training system of Con-trex.kinematic and high speed photography to test indexes like muscle strength and movement structures of every group for consequence analysis through SIMI-motion sports analysis software. Data processing was analyzed by SPSS 11.5.Results: After the strength training, the hamstring and quadriceps femoris strength experiences a significant increase while after extensor strength training, extensor strength increase sharply yet flexor strength does not as sharp as the former one. After six weeks of training, the average acceleration of breaking and speeding up during the direction changing of shuttle run, increased in every group. After twelve weeks of training, the average acceleration of breaking, increased significantly in extension to flexion group and always extension group.The change in the other groups are not significant. The average acceleration of speeding up, increased significantly in extension to flexion group and the change in the other groups are not significant.In a certain range, with the ratio of hamstring to quadriceps femoris strength increasing, the average acceleration during the direction changing of shuttle run incresed. On the other side, there are no obvious changes of the other kinematic indexes of movement structures.Conclusions: With increasing ratio of hamstring to quadriceps femoris strength, some kinematic indexes of movement structures change during the shuttle run. The average acceleration during shuttle runs changes significantly and the changes of the other kinematic indexes of movement structures are minute. As a result, reasonable training to improve the proportion of rear-thigh muscles is helpful to improve breaking, turning body and speeding up abilities in shuttle run.