Principle of the optimum acceleration path | The biomechanical principles

Principle of the optimum acceleration path

Acceleration is defined as the change in speed per unit of time. It can occur both in positive and negative form. In sports, however, only positive acceleration is important.

The acceleration depends on the ratio of force [F] by mass [m]. Consequently: If a higher force acts on a lower mass, the acceleration increases. The principle of the optimal acceleration path, as one of the biomechanical principles, aims to give the body, part of the body, or a piece of sports equipment a maximum final speed.

However, since biomechanics are physical laws in relation to the human organism, the acceleration path is not maximum but optimal due to muscle physiological conditions and leverage. Example: The acceleration distance during hammer throwing could be extended many times over by additional rotary movements, but this is uneconomical. A squatting too deep during the stretch jump leads to an extension of the acceleration distance, but causes unfavourable lever ratios and is therefore not practical.

In recent sports science this law is called the principle of the tendency of the optimal acceleration path (HOCHMUTH). The focus is not on reaching a maximum final speed, but on optimizing the acceleration-time curve. In shot put, the duration of the acceleration is not important, it is only about reaching the final speed. In boxing, on the other hand, it is more important to accelerate the arm as fast as possible in order to prevent the opponent from taking evasive action. In shot put, the beginning of the acceleration can be kept low and only towards the end of the movement is there a high acceleration.

Principle of coordination of partial impulses

An impulse is the state of motion in direction and speed [p=m*v]. With this principle it is again necessary to distinguish between coordination of the entire body mass (high jump) or coordination of partial bodies (javelin throw). In close connection with the coordinative abilities (especially coupling ability) all partial body movements/partial impulses must be coordinated temporally, spatially and dynamically.

This can be clearly seen in the example of serve in tennis. The tennis ball can only reach a high final speed (230 km/h) if the entire partial impulses follow each other immediately. The result of the high impact movement on the serve starts with stretching the legs, followed by a rotation of the upper body and the actual impact movement of the arm.

The individual partial impulses are added together if the execution is economical. Furthermore, it must be noted that the directions of the individual partial impulses are in the same direction. Here again a compromise between anatomical and mechanical laws must be found.

Principle of reciprocity

The principle of reaction as one of the biomechanical principles is based on Newton’s third law of reaction. It states that a force generated always generates an opposite force of equal magnitude in the opposite direction. The forces that are transmitted to the earth can be neglected due to the mass of the earth.

While walking, the left arm is simultaneously brought forward to the right foot, because the human being cannot transfer forces to the earth in the horizontal direction. A similar situation can be observed with the long jump. By bringing the upper body forward, the athlete simultaneously causes a lifting of the lower extremities and thus gains advantages in jumping distance.

Further examples are the stroke throw in handball or forehand in tennis. Based on this principle the principle of the turn back kick is used. As an example, one can imagine standing in front of a slope. If the upper body receives a forward motion, the arms start to circle forward to create an impulse on the upper body. Since the mass of the arms is less than that of the upper body, this must take place in the form of fast circles.