| Research purposes: This research uses sports biomechanics research methods and means to conduct biomechanical analysis on the difficult movements of competitive aerobics B589.The purpose is to find out the characteristics of kinematics and muscle strength in each stage of the difficult movements of competitive aerobics B589,and provide theoretical basis for the analysis and improvement of athletes’ sports skills in the future.Research methods: Using the methods of literature,interview,experiment and mathematical statistics,with the help of three-dimensional high-speed camera(Sony/Sony DSC-RX10M4 long focus black card digital camera)and America Noraxon electromyography tester and other experimental instruments,we conducted synchronous collection of electromyography signals,angles and videos,and successively tested six national athletes of male competitive aerobics,Megawin 2.4software,combined with synchronous video and SIMI motion 3D motion analysis software,was used to analyze the data of the selected 8 muscles(left and right anterior deltoid muscles,rectus abdominis,rectus femoris,and medial head of gastrocnemius)and key angles at each stage of the whole movement,The main analysis indexes were the time to complete the action,the center of gravity displacement,the joint angle,the order of muscle activation,the integral EMG value,the contribution rate and the root mean square amplitude.After the original EMG data and kinematics data are processed,Excel software is used for statistical processing and analysis.Research results:(1)The hip joint buffering angle during the takeoff and extension stage of the B589 difficulty action is between 30 °-90 °,the knee joint angle is between45 °-85 °,and the ankle joint angle is between 35 °-75 °.The higher the score,the greater the joint buffering angle of the athlete.During the 360 ° rotation stage,the higher the score,the more standardized the movement and bending posture.The larger the knee and ankle joint angles,the smaller the hip joint angle,During the landing buffering stage,athletes have the best landing effect when the elbow joint buffering angle is between 65 °-75 °,the shoulder joint buffering angle is between 20 °-55 °,and the wrist joint buffering angle is between 5 °-15 °.When the B589 difficult movement turns 360 ° and soars,The higher the score,the more standard the athletes’ posture,the greater the angle of knee and ankle,and the smaller the angle of hip.(2)When athletes complete the take-off phase of B589 difficult movements,the left and right rectus femoris and the medial head of gastrocnemius muscle muscle are the first to be activated.The left and right rectus femoris,the medial head of gastrocnemius muscle muscle,and the anterior band of deltoid muscle muscle contribute a large proportion in this phase,and are the main force muscles.The left rectus femoris has the largest RMS standard conversion value and strong recruitment ability,which has a certain relationship with the action posture of taking off.(3)In the takeoff phase,the medial head of the left and right gastrocnemius muscle muscles is activated first,and then the rectus abdominis.The overall contribution rate of most of the muscles on the right side is higher than that of the left side,of which the contribution rate of the anterior bundle of the left and right deltoid muscle muscles and the rectus femoris muscles is the largest.These four muscles play an important role in turning the movement into a bending posture.(4)At the landing stage,the body’s center of gravity slightly shifted to the right after landing,and the overall contribution rate of most muscles on the right side was higher than that of the left side.The left and right deltoid muscle anterior bands were first activated,and the contribution rate and RMS standard conversion value were the largest.Research conclusion:(1)When athletes complete the B589 difficulty action,they first need to obtain a large instant takeoff straight speed and a high takeoff height,and secondly,they also need the ability to control their body posture in the air,physical fitness,and skill requirements.(2)During the takeoff phase of the B589 difficulty action,the lower limb muscles shift from centrifugal contraction to centripetal contraction,and the left and right rectus abdominis primarily maintain the stability of the body’s center of gravity during this process.Therefore,the low contribution rate of the rectus abdominis cannot be ignored.(3)The lower limb muscles are first activated during the soaring phase of the B589 difficulty movement,and the arm swing,core stability,and hip and knee joint angles are particularly important in the turning and bending movements.Straightening the foot can reflect the athlete’s posture beauty.(4)During the landing stage of the B589 difficulty movement,maintaining balance and stability in posture requires the muscle strength in the core area to form a "rigid body" in the trunk,in order to provide a stable starting point for the distal end to complete the difficulty movement with high quality and avoid joint damage. |
