Effect of six weeks core stability trainings on valgus angle during drop shot for women squash players / Navadeh Sofia
Lower limb injury outbreak is inevitable in most of sport branches. One of the most common injuries of this kind is Anterior Cruciate Ligament (ACL) tearing. Valgus degree of knee during performing sportive movements is one of the most important risk factors for incidence of ACL injury. By considering the kinetic chain that leads to this injuries and reinforcing the open end of this chain, the creation and transferring of unwanted force that causes excessive torque in the knee could be controlled. In movements that the lower end of the kinetic chain is fixed, any motion in upper end of the chain would be transferred to the lower parts. Therefore in movements like drop hit in Squash that consists of sudden stop during running, stability of core and hips will avoid transferring of excessive force to knee by kinetic chain. In order to investigate the effect of core stability on Valgus angle during drop hit in Squash, 11 female professional Squash players are selected and for each of these players, especial core stability trainings are designed. These trainings consist of 7 kind of core stability exercises that performed in 3 levels. Each level consists of 2 weeks training plan that runs in 6 days a week. Valgus angle was investigated by implementing 2 tests before and after of doing these exercises. These tests are: 1- Mcgill's endurance test, 2- Video processing analysis of performing drop hits by the players. In Mcgill's endurance test, three index of trunk flexor, trunk extensor and bilateral side bridge was studied. In video processing analysis section, after placing the markers, the player perform drop hit and a 300 fps camera recorded her movements. By having the results of these tests, 2 index defined for core stability and Valgus angle. The relation between these indexes were investigated by Cross Correlation method. For improving the accuracy of measurements, an Artificial Neural Network was designed to eliminate the effect of players initial condition on the tests. At last it was concluded that there is a linear relation between the core stability index and Valgus angle index.