Research On The Technical Characteristics Of Body Rotation During The Swimming Process Of Chinese Elite Swimmers

PurposeBy studying the characteristics of shoulder and hip rotation in the competition of active high-level swimmers in China,this paper analyzes the relationship between rotation technology and speed of athletes in different events,further explores the rotation technology law in the swimming process,and provides theoretical basis for optimizing technical movements of high-level athletes in China.MethodsThrough literature research,the research status and trend of body rotation technology in swimming are clarified,and the characteristic evaluation indexes of body rotation are screened;Using the national swimming team wearable equipment research and development project "Swimming Intelligent Measuring Instrument",the body posture data of 18 national swimming team athletes in the test match are collected in real time,and the angle peak value,valley value and real-time data of the athletes’ swimming process are obtained through the embedded function of Matlab(Matrix Laboratory),and then the parameters of rotation amplitude,speed,timing and frequency are obtained,and the rotational symmetry index and rotational deviation index are obtained by integrated calculation.Using Microsoft Excel 2021 and IBM SPSS statistics 26 software,the maximum,minimum and mean values of rotation technical parameters are compared.Combined with the special technical characteristics of freestyle and backstroke,breaststroke and butterfly,a comparative analysis is carried out.Results1.freestyle: The faster the swimming speed,the smaller the body rotation range,and the shoulder rotation range and speed are greater than the hip rotation;The body rotation range of 50m freestyle is less than 400m freestyle,the rotation speed is opposite,and the rotation time is earlier.The difference of shoulder and hip rotation frequency of the former is smaller than that of the latter,and the rotational symmetry index is both higher.2.Backstroke: The greater the body rotation,the slower the rotation speed,and the greater the hip rotation than the shoulder rotation;The rotation range of 100m backstroke is less than 200m backstroke,and the rotation speed is opposite;The timing of left and right rotation is basically the same,and the timing of hip rotation is earlier than shoulder rotation;The body rotation frequency of 100m backstroke is higher than 200m backstroke.Among them,the shoulder is generally asymmetrical,and the hip is more symmetrical.3.Breaststroke: The rotation range of the shoulder is greater than that of the hip,the rotation speed is faster than that of the hip,and the rotation time of the hip is slower than that of the shoulder;The rotation range of 100m breaststroke is less than 200 breaststroke,and the rotation speed is faster;The rotation time of 200m breaststroke cycle is more sufficient and the rotation frequency is lower;The hip rotation deviation of 100m and 200m breaststroke is less than the shoulder rotation deviation,and other indicators are consistent.4.Butterfly stroke: The rotation speed of the shoulder is slower than that of the hip,but it fluctuates more,and the athlete’s body posture is similar to a sine curve;The shoulder and hip rotation speed of 100m butterfly is faster than that of 200m butterfly,and the rotation time is earlier and the rotation frequency is higher.In 100m and 200m butterfly,the fluctuation rotation deviation between shoulder and hip is large,and the rotation deviation of shoulder is greater than that of hip.5.Comparison between freestyle and backstroke: The shoulder rotation range of freestyle is greater than that of backstroke,and the shoulder and hip rotation speed of backstroke athletes is slower than that of freestyle athletes,and the hip rotation difference is larger;With the extension of distance and the decrease of pace,the shoulder rotation speed of freestyle athletes shows a decreasing trend,but the backstroke shows the opposite trend.6.Comparison between breaststroke and butterfly stroke: The shoulder rotation and hip rotation of breaststroke athletes are greater than those of butterfly swimmers,and the rotation of breaststroke athletes tends to increase with the increase of the run.Short-distance breaststroke and butterfly have higher shoulder undulation and faster rotation speed than long-distance swimmers,and the hip rotation speed of butterfly is faster than breaststroke,and with the decrease of swimming speed,the hip rotation speed of breaststroke and butterfly gradually decreases.Conclusions1.The advantages and disadvantages of body rotation technology have an important influence on swimming performance,and swimming speed is correlated with the range,speed,timing,and frequency of body rotation of swimmers.Swim that rotates around the longitudinal axis shows a higher symmetry index of the body,while swim that rotates around the horizontal axis shows a larger deviation of the trunk ups and downs.2.The stability of the trunk is the key to swimming technique.There are differences in shoulder and hip rotation in the four swimming strokes.The shoulder rotation range in freestyle is greater than that in hip,while in backstroke,the shoulder rotation range and speed in breaststroke and butterfly are higher than that in hip,which shows that the leading force points of body parts in different swimming strokes are different.3.Compared with long-distance swimmers,short-distance swimmers show the characteristics of faster rotation speed,smaller rotation range,earlier rotation opportunity and higher rotation frequency.The remarkable characteristics of long-distance swimmers are more full periodic rotation and longer rotation time.4.There is a trend that the swimming distance increases,the rotation range decreases and the rotation speed increases between different strokes;The difference of the athletes’ rolling posture is greater than that of pitching posture,which shows that the performance of the two ends of the trunk is an important index to reflect the paddling effect,trunk muscle elasticity and swimming skill.