The Comparison Of Two Kinds Of Freestyle Turn-back Skill

ObjectiveThis paper is contract,analysis and study the two kinds of different freestyle change-direction skill(“Supine style” and “ Traditional Prone style”)via two groups(experimental group and contrastive group)swimmers full course kinematic parameter,to find out the difference and character of these two kinds of freestyle change-direction skills,and find out which one is more economical,more effective and more faster,to helping swimmers enforce the basis of freestyle change direction skill and enhance the teaching and training.MethodsHaving an experiment to test the 10 simmers who are experimental objective,to shot by 3 cams which are 2 cams above water(one for steady shooting,one for follow shooting).Getting emerging distance,turning body's joint angle,diving depth,turning depth,diving swimming average speed,swimming average speed,200 m freestyle total time kinematic parameter by using APAS and DARTFISH software.And contract and study change-direction via watching video,asking experts and researching books.Results(1)In the comparison of the average distance of emerging water between the experimental group and the control group,the experimental group was 9.16±0.51,the control group was 8.52±0.33,and the experimental group was longer than the control group 0.64 m.In the comparison of average total diving time,the experimental group was 9.18±1.76,and the control group was 8.33±1.72,the experimental group was longer than the contract group 0.85 s.In the comparison of the diving average speed,the experimental group was 1.19±0.13 and the control group was 1.02±0.17.The experimental group was faster than contract group0.17m/s.In the contrast of the diving depth,the experimental group was 1.28±0.11 and the control group was 0.83±0.18,the experimental group was deeper than the contract group 0.45 m.In the comparison of rolling depth,the experimental group was 0.80±0.07,and the control group was 0.68±0.11,the experimental group is deeper than the contract group 0.12 m.(2)In the knee Angle of comparison,the experimental group was 62.8 ° ±2.64 °,and the control group was 69.06 ° ±15.07 °;In the comparison of the hip Angle,the experimental group was 114.94 ±16.75,and the control group was 101.52±47.98.(3)In the 200 m freestyle test,the score which who finished with the supine change-direction skill which are 2'52''32?2'53''94?2'52''10?3'09''70?3'09''60 respectively,the score which who finished with the prone change-direction skill which are 2'56''86?2'54''34?2''54''35?3'15''55?3'16''08 respectively,the 200 m freestyle swimming with the supine skill was faster than the prone skill,which are 4s,1s,2s,6s and 7s respectively.Conclusion(1)The supine changed-direction skill is faster than the prone skill in the phase of the under water kicking of the average speed,and the distance after changed-direction(rolling)is also longer than the prone skill,supine skill is better than the prone skill.(2)Due to the supine skill kicking under the water does not fight with the buoyancy in the underwater kicking phase,the supine skill is more easier and more efficient than the prone skill.(3)In the 200 m freestyle final score contrast,the first 100 m achievement gap is not big,but after 100 m,the gap was gradually widening,it shows that with the increase of turn times,the supine skill gets the advantage in the long freestyle swimming.In the long-distance freestyle project,you should adopt the supine changed-direction skill.