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Each time a skill is practised, it is known as performance. Before the skill is performed, it has to be learned. Learning involves understanding and then being able to perform the skill over and over again.
Basic movement principles apply to all physical activity. Understanding and identifying them is an important part of observing, analysing and improving performance. Let's take a look at some of these principles.
Skilled Movement
A physical skill requires the muscles and joints of the body to be used in specific ways. The skills in a particular activity need to be known, as well as how they are to be observed, analysed and improved.
For example: To observe and analyse a lawn tennis player performing a forearm drive, attention must be on:
n Movement to the ball - the contact with the ball
n Body position for the shoot - the follow-through
n The racket swing - the recovery from the shoot.
If any part is found faulty, the muscle/joint action can be analysed, e.g., the wrist action in a flick; and improvements can be made. A checklist could be used to identify any element that needs improving, then practice sessions are organised to improve the faulty element.
Motion and force
The laws of motion are the basis for the principles of movement. Knowing them can help fine-tune performance. Motion is about movement, that is, the change of position of an object.
Newton's Third Law states that "when one object exerts a force on a second object, there is a force equal in magnitude, but opposite in direction exerted by the second object on the first".
This reaction force determines the change in speed and direction of the movement. For e.g., in any 'feint' or 'sidestep', you need to push down hard with your leg on the ground in the opposite direction to the one in which you want to go. Runners push backwards on the starting blocks with their legs in order to go forward.
It is important to observe and analyse the change in direction and/or speed of any movement in terms of Newton's Third Law.
Newton's Laws:
1. The law of inertia
An object will stay put until a force moves it, and an object will keep on moving until a force acts upon it. No movement occurs until a force is applied to it. For example, a golf ball does not move until muscles apply a force to the club, then the club applies a force to the ball. The ball will move in a set direction, until an outside force (wind, gravity or a tree), changes its direction and then the surface of the course will stop it from rolling.
2. The law of acceleration
The speed of an object is directly proportional to the force applied and the direction in which it is applied. For example, in golf, a lot of force is applied in the execution of the 'drive' so that the ball accelerates quickly and travels a long way. Less force is applied to 'putt', so the ball travels slowly. If the force is applied to the side of the ball, it will 'hook' or 'slice'. This law can be applied to any game requiring the throwing or kicking of a ball.
3. The law of opposition
As mentioned earlier, when an athlete pushes backwards into the blocks, the blocks push back at him and he is propelled outwards and forwards.
Stability
The stability of your body affects your movements. Stability can be improved as follows.
1. Base of support: The base of support involves the relationship between the athlete and the surface they are performing on. Increasing the area of the base of support will create more stability. For example, if you stand with your feet shoulder width apart, you are more stable in relation to any force applied from the side, than if your feet were close together.
2. Centre of Gravity: This is a point at which the body weight is evenly distributed in any position. When your centre of gravity is above your base of support, you are stable. When it is outside your base of support, you are in an unstable position - a position of imbalance. If the centre of gravity is lowered, e.g., lowering the body weight by bending the knees; or if your centre of gravity is brought nearer to the middle of your base, more stability will be created. It is important that the position of the centre of gravity is considered in the observation and analysis of movement.
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