Biomechanics of Dynamic Posture in Sports Exercises and Methods of Its Formation

The article aims to identify and quantify the biomechanical factors that determine the power demand for performers of sports exercises with dynamic posture. Analysis, as a method of biomechanics, allows assessing the dynamics of the biomechanical state of an athlete performing a sports exercise. The function of the biomechanics method is the synthesis of movements - the ability to predict the trajectory and behavior of the biomechanical system over time under given initial conditions of movement. The article considers one of the methods of the biomechanical synthesis of movements in the conditions of support with dynamic posture, based on a model representation of the movement of a biomechanical system in the form of a physical pendulum, which is determined by the need to record articular angles at a certain time interval of the biosystem's movement. The angular acceleration of an object of motion is determined from the dynamic law of motion of the physical pendulum, and, taking into account the mass-inertial characteristics of the biomechanical system, equations are formed to determine the parameters of the control moments of muscle forces in the athlete's joints that ensure the fixation of the athlete's posture. Consideration of the method is based on the mathematical apparatus of describing the movement of a gymnast in a large turn back on the crossbar with the preservation of dynamic posture. The method allows giving a numerical estimate of the parameters of the control moments of muscle forces in the joints of an athlete with reference to an arbitrary orientation of the biosystem on a plane, which eliminates the need to use time indicators of movement in calculation algorithms. In a computational experiment on a computer, the parameters of the control moments of muscle forces in the joints of an athlete in a large reverse rotation on a crossbar with dynamic posture were obtained on the basis of a model representation of the movement of the musculoskeletal system of the athlete's body in the form of a physical pendulum. A mathematical model for estimating the parameters of the control moments of muscle forces in the joints of an athlete for a three-link biomechanical system with specified mass-inertia characteristics of the model links is implemented in a computer program based on the MS Excel spreadsheet processor. The output provides numerical support for the simulation results. Based on the performed biomechanical analysis of the power component of recording the angle in the shoulder and hip joints of a gymnast in a large turn back on the crossbar, a method for forming the motor skill of dynamic posture in gymnastic exercises is developed. An example of a methodological sequence of drawing up a linear scheme for mastering dynamic posture by the method of programmed learning is given. It is shown that the developed computer model of the method for evaluating the control moments of muscle forces in the joints of an athlete implements the forecast of an individual power request required for an effective development of the technique of a competitive exercise with dynamic posture.

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