| Objective:This study was conducted to study the technical action of in situ one-handed over-the-shoulder shooting（free throw）under different load intensities of 9 basketball level II athletes from Xi’an Sports College.The study was conducted to investigate the differences in biomechanical characteristics of basketball players’ one-handed over-the-shoulder shooting,and to provide theoretical references for the rational use of shooting techniques in the daily teaching practice and sports training of athletes,in order to improve the hitting rate in actual combat.Methods:In this study,nine male Division II basketball players from Xi’an Institute of Sports were used as subjects,and biomechanical data were collected by applying SONY Cyber-Shot high-speed camera and NORAXON surface electromyography tester to simulate the subjects’ in situ one-handed over-the-shoulder shooting technique under different load conditions during the game.The EMG data were processed with Mega Win software for rectification,filtering and smoothing,and the final data were processed in SPSS22.0 software for statistical analysis,calculation and plotting.Results of the study:1.kinematic aspects: in the three different load states of the simulated game,during the shooting process,the elbow joint had the largest amplitude of change and the fastest angular velocity.the values of the amplitude of change in the elbow joint of guards,forwards and centers in the low load state were 91.9°,91.6° and 90.3°,and the values of angular velocity were 85.5°/s,86.0°/s and 88.9°/s,respectively.in the medium load The values of the amplitude of change in the elbow joint at guard,forward and center under medium load were 96.4°,96.2°,93.5°,and the values of angular velocity were 96.1°/s,94.8°/s,96.3°/s,respectively.The values of the amplitude of change of the hip joint were 24°,19.0°,14.3°,and 22.1°/s,21.3°/s,and 22.6°/s.The values of the amplitude of change of the hip joint were 24°,19.0°,14.3°,and 22.6°/s for the guard,forward,and center under medium load,respectively.The values for the amplitude of hip change at guard,forward and center under high load were 21.4°,16.7° and 12.0°,respectively,and the values for angular velocity were 17.8°/s,16.4°/s and 16.7°/s.The values for the amplitude of hip change at guard,forward and center under high load were 28.6°,20.9° and17.3°,respectively,and the values for angular velocity were 13.8°/s,12.6°/s and13.9°/s,respectively./s,and 13.9°/s,respectively.In the same load state,although the kinematic data of players in each divisional position varied,all joint angles of players in different divisional positions had higher technical movement reasonableness for shooting under medium load state and poorer technical movement performance under high load state,which indicates that the load state has more obvious influence on technical movement.2.Electromyography:（1）In the three different load states of the simulated game,the biceps values measured in the RMS of guards,forwards and centers during the whole shooting process were the highest,and the values of guards,forwards and centers in the low load state were 123.6m V,116.0m V and 101.6m V respectively,and the values of guards,forwards and centers in the medium load state were 133.0m V,126.6m V and 116.3m V respectively.126.6m V,116.3m V,and 114.6m V,109.2m V,99.3m V for guards,forwards,and centers respectively in the higher load state.rectus abdominis values were the lowest,29.0m V,24.3m V,22.3m V for guards,forwards,and centers respectively in the lower load state,and 31.0m V,31.0m V for guards,forwards,and centers respectively in the medium load state.25.3m V,23.0m V,and17.0m V,15.3m V,13.3m V for guards,forwards,and centers respectively in the higher load state.（2）In the three different load states of the simulated game,the highest biceps values were measured by IEMG,102.6m Vs,.90.3m Vs,.83.0m Vs.for guard,forward and center under low load state,104.0m Vs,.101.6m Vs,.96.3m Vs.for guard,forward and center under medium load state,respectively.The lowest value of rectus abdominis was 19.3m Vs,.16.6m Vs,.15.6m Vs.for guard,forward and center under low load condition,20.0m Vs,.17.3m Vs,.16.6m Vs.for guard,forward and center under medium load condition..s,16.6m Vs,.and 15.3m Vs,.13.6m Vs,.and 13.0m Vs.for the three positions in the higher load state,respectively.The results of the study showed that although the EMG data varied among the positions of the players in the same load state,the players in the same position had higher muscle activation and higher discharge in the medium load state;and lower muscle activation and lower discharge in the high load state,which proved that the load state had a very obvious effect on the muscles.Conclusions of the study:1.The kinematic data of in situ one-handed over-the-shoulder shooting by players in different positions under three different load states showed that the technical action of shooting was more reasonable in the medium load state and less reasonable in the high load state.In the field,the greater the extension of shoulder,elbow,knee and ankle joints,the more stretching the movement is,the better the shooting effect;the smaller the extension of hip joint,the higher the body stability,the better the shooting effect,and the core training should be conducted to enhance the stability of hip joint.2.In the three different load states,guards,forwards,and centers in situ one-handed over-the-shoulder shooting muscle force order has consistency are:gastrocnemius,rectus femoris first at the same time,followed by deltoid,then biceps,then rectus abdominis,and finally triceps force,muscle according to a reasonable order of force,in order to ensure the smooth technical action,enhance the shooting effect.3.Under three different load states,the EMG data of guards,forwards and centers showed higher muscle activation and higher discharge in the medium load state;and lower muscle activation and lower discharge in the high load state.Therefore,athletes should strengthen muscle strength and muscle endurance training and pay attention to physical training in order to maintain a good competitive condition on the field. |
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