Movement Analysis: Lever Systems

Understanding Lever Systems

Lever systems are a basic part of the mechanics of movement in the human body.
They involve a lever (bone), a fulcrum (joint), an effort (muscular force) and a load or resistance.
Understanding these systems can help us analyse movement and improve physical performance.

Types of Lever Systems

There are three types of lever systems, classified according to the positions of the fulcrum, effort, and load.
1. First class levers: The fulcrum is between the effort and the load. An example is the seesaw motion of the head on the neck.
2. Second class levers: The load is between the fulcrum and the effort. An example is the action of the calf muscles when standing on tiptoes.
3. Third class levers: The effort is between the fulcrum and the load. An example is the action of the biceps during a bicep curl.

First-Class Levers

First class levers allow a large load to be moved with a relatively small effort.
These are typically used for balance, for example, in the seesaw motion of the head on the neck.

Second-Class Levers

Second class levers allow a large load to be moved with a relatively small effort.
These are typically used for power movements, for example, when standing on tiptoes.

Third-Class Levers

Third class levers require a large amount of effort to move a small load.
These are typically used for speed and range of movement, for example, the action of the biceps during a bicep curl or the action of the quadriceps when kicking a ball.

Lever Advantages

Lever systems enhance the body’s strength, speed and range of movement, which are all important for success in sport and physical activities.
Understanding lever systems also helps in understanding the principles of biomechanics which can improve technique in sports and reduce the risk of injury.