Abstract:
During the execution of a spike, net defense, and volleyball serve performed at high speed, there is a possibility of injury to the shoulder, elbow, and wrist joints, and even fractures of the hand bones. For example, if it is assumed that a ball is served at a speed of 25 m/s and the impact time is 0.01 seconds, given that the weight of the ball is 0.27 kg, we can calculate the amount of applied force using the following formula: F = dp/dt = 25×0.25/0.01 = 625 N This force will exert significant pressure on the wrist, elbow, and shoulder joints, allowing for the calculation of the amount of force applied to the muscles in the joints. To calculate this force, we need the impact time (dt) and the velocity of the ball. In this research, we defined a mechanical model that can theoretically easily determine the velocity, force, and pressure applied to the joints. In order to measure the velocity of the ball in a spike or serve, a 20 kg ballistic pendulum suspended from a height of 4 meters was used. This pendulum was originally used to measure the ball's velocity. Based on the laws of the pendulum, to calculate the velocity, we have: VBO = MP?2gh/(1+e)mB where in this formula VBO is the initial velocity of the ball, MP is the mass of the pendulum, mB is the mass of the ball, e is the coefficient of restitution of the ball, and h is the height the pendulum has after impact. Additionally, the amount of force applied to the pendulum was calculated based on the potential energy of the pendulum after impact and the work done on it, using the following formula: FP = MpVp/2t The method presented in this way is a simple method for calculating force and can even be used in sports such as football and volleyball. By using the physical characteristics of the players, the amount of pressure or impact applied to different parts of the body can be obtained based on the calculated force.
Machine summary:
A new method for measuring force, velocity, and torque applied to the wrist, elbow, and shoulder joints in volleyball jump serve and spike Shahram Khanzadeh, Dr. Morteza Shahbazi Moghadam, Dr. Mehralie Hemmatinejad Faculty of Physical Education, University of Guilan Contents: Abstract 931 Introduction 041 Research Methodology 141 Research Findings 241 Discussion and Conclusion 341 Abstract: During the execution of a spike, net defense, and volleyball serve which is performed with high velocity, there is a possibility of injury occurring in the shoulder, elbow, and wrist joints, and even fractures of the hand bones.
For example, if it is assumed that a ball is served at a velocity of 52 meters per second and the impact time is 0/10 seconds, considering that the weight of the ball is 72/ kg, we can calculate the amount of applied force using the following formula: (Refer to the page image) This force will apply significant pressure to the wrist, elbow, and shoulder joints, allowing for the calculation of the amount of force applied by the muscles to the joints.
3-2-According to Table 3, the amount of torque applied to the elbow joint during the jump serve is higher in skilled individuals than in beginners, which itself indicates a higher technical skill level in the skilled groups and the application of more force to the ball.
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