A Simple Explanation of Biomechanics

Biomechanics looks at 2 key areas:

1. Kinetics - forces acting on the body

2. Kinematics - movements of the body

The principles of these forces can be explained using Newtonian Mechanics (yes, Isaac Newton).

The Law of Inertia:

Newton's 1st law of motion states that ‘an object at rest will stay at rest, or an object in motion will stay in motion, at the same speed in the same direction, unless acted upon by an unbalanced force’. An athlete standing waiting to perform a sprint start has inertia or a ‘reluctance to move’ and therefore requires the athlete to produce force to ‘break their inertia’.

The Law of Acceleration:

Newton’s 2nd law of motion states that ‘the acceleration of an object is dependent upon the magnitude of force applied to the object and the mass of the object’ and can summarised with the following equation:

Acceleration = Force divided by Mass.

For example, if you want to accelerate a racket, a ball, your body, where the mass (or weight) of the object is fixed, the acceleration is dependent on the size of the force you can apply.

The Law of Reaction:

Newton’s 3rd Law states ‘every action has an equal and opposite reaction’. The magnitude of force and the direction at which that force is applied are both of great importance within sports. When an athlete applies force to the floor, an equal and opposite reactive force is applied back to the athlete. This is known as Ground Reaction Force. If an athlete wishes to jump vertically upwards, then their force needs to be applied vertically downwards.