Research On The Biomechanical Characteristics Of Lower Limbs Of Two Different Techniques Of In-situ Step Jumpers In Basketball

ObjectiveThe biomechanical characteristics of the lower limbs of two different techniques in basketball were studied by means of surface electromyography(EMG),kinematics and dynamics,and the regularity and difference of the two different techniques were analyzed when the basketball players broke away from the defense to the left or to the right under the condition of holding the ball in place.MethodEight basketball athletes from Beijing Sport University were selected to collect the surface EMG,kinematics and dynamics data of the lower limbs of the in-situ same side and in-situ different side step-back jumper.Indicators:Timing characteristics of lower limb muscle force,integral EMG and muscle contribution rate;Three-dimensional motion Angle of hip,knee and ankle,height of body vertical center of gravity and vertical ground reaction force.Results1.The right tibialis anterior muscle is the first to be activated,and the left rectus femoris is the last.The longest time of exerting muscle of in-situ ipsilateral stepback jumper was the right tibia anterior muscle,while that of in-situ dissimilar stepback jumper was the left biceps femoris,and the two in-situ stepback jumpers had the shortest exerting time of left leg rectus femoris muscle.2.The medial head of gastrocnemius muscle and tibialis anterior muscle of right leg have higher activation degree and greater contribution rate in the same side in situ,while the medial head of gastrocnemius muscle and tibialis anterior muscle of left leg have higher contribution rate in the same side in situ.3.The moment of landing on the front swing leg,the moment of maximum buffer on the front swing leg,and the moment of leaving the ground on the back of the kick leg:there was significant difference in the abaxial Angle between the left leg of the in-situ same-side step-back jumper and the right leg of the in-situ step-back jumper(P<0.05).At the moment of landing on the front swing leg,there was significant difference in the knee flexion Angle between the right leg of the same side step step jumper and the left leg of the different side step jumper(P<0.05).The maximum buffer time of the front swing leg and the moment of the two legs off the ground when kicking back:there was significant difference in the internal rotation Angle between the right leg of the in-situ same-side step-back jumper and the left leg of the in-situ off-side step-back jumper(P<0.05).There was significant difference in the knee pronation Angle between the right leg of the in-situ same-side step-back jumper and the left leg of the in-situ off-side step-back jumper(P<0.05).At the moment of landing on both legs,there was significant difference in the pronation Angle between the left leg and the right knee when the left leg was shot from the same side by stepping back from the ground(P<0.01).The moment of the two legs off the ground in the take-off shot:there was a significant difference in the hip flexion between the left leg of the in-situ step-back jumper and the right leg of the in-situ step-back jumper(P<0.01),and there was a significant difference in the hip flexion between the right leg of the in-situ step-back jumper and the left leg of the in-situ step-back jumper(P<0.05).4.The vertical center of gravity height of the in-place reverse step jumper on the opposite side is less than that of the in-place reverse step jumper on the same side at the moment when both legs touch the ground(P<0.05).5.There is no significant difference between the first and second peak forces of the front swing and the back step during the support leg landing.ConclusionThe lower limb movement characteristics of two different techniques of step-back jumper in situ:1.For both of the two different techniques,the center of gravity of the body is to the right when the legs support the cushion,and the center of gravity is to the left when the ground kicks off.2.The quick start of the two different techniques of the step-back jump shot is completed by the tibialis anterior muscle being activated to make the foot move and then the knee and hip joint.The muscle group around the ankle joint has a large load and a high degree of participation in the completion of the action.The medial head of the tibialis anterior muscle and gastrocnemius muscle are activated to a high degree and their contribution rate is high.3.The range of front swing and back retreat is larger,the center of gravity is lower,and the flying height is higher after the shooting take-off.