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Movement analysis – lever systems in sport and physical activity, Captura…
Movement analysis – lever systems in sport and physical activity
Lever systems in the
body
A lever system within the body would use a lever (bone) to move an object, for example, when we run we are the object being moved, but when kicking a ball, the object being moved is the ball.
The load is the object requiring moving, the effort is the muscular force we use to move the object, the fulcrum is the joint around which the movement occurs and the bones of the skeleton are the levers.
A tree would be too heavy to lift, but a person could move the tree a little by using a lever system.
First class levers
Nodding of the head is another example of a first class lever system, important in sport when watching the flight of a ball for example; in this example the load would be the weight of the head.
There are a limited number of examples of first class lever systems in the body.
For example, due to where the triceps attach to the elbow joint, elbow extension is considered to be use of a first class lever system.
Further explanation of this can be left for level 3 Sport or PE courses; it is sufficient for you to appreciate that elbow extension involves a first class lever.
Third class levers
For example, a biceps curl uses a third class lever system, as does hitting a ball with a racket or bat, or at the knee when we kick a ball, or the hip when we run.
You can tell when it's a first class lever system as the fulcrum is in-between the other components; in the second class it is the load and in the third it is the effort.
Mechanical advantage and disadvantage
The position of each part of the lever system relative to each other will determine whether the lever has a mechanical advantage and can be used to lift heavy loads or a disadvantage where greater effort is needed but the load can be moved a greater distance and with speed.
Lever systems where a greater force needs to be applied than the load to be moved is said to provide a mechanical disadvantage.
Movement analysis – lever systems in sport and physical activity
Planes of motion
in multiple planes and this is something you might need to study if you go on to study planes and axes at university. For this course you only need to be aware of the three main planes and axes and the basic movement each allows.
The major body axes
in order for these movements to take place there has to be an axis (which goes through a joint) for the bones of the skeleton to move about.
For example, when we talked of a biceps curl involving flexion and extension in the sagittal plane we know this movement is only possible because of the elbow joint.
In this example an axis passes through the elbow joint allowing movement around it.
Second class levers
The one with possibly the greatest application for sport is the second class lever system formed between the ball of the foot, the gastrocnemius and the load of the bodyweight as we point our toes, or go onto our toes (the Load foot is the lever bar).
