Principles of Biomechanics in Sports

The nine principles of biomechanics form the minimum set of core principles that can be applied to all human movements. They can be organised into two broad groups:

• principles dealing mainly with the creation of movement — the process of producing motion; and
• principles dealing mainly with the outcome of projectiles — the product, such as how far or how accurately something is thrown.

These generic principles are drawn from the work of several biomechanists (for example Norman, 1975 and Hudson, 1995), who developed principles meant to apply to every human movement. Other writers have proposed principles for categories of movement — throwing, catching, running — or for specific skills. A few biomechanists even argue that truly general principles are hard to identify and of limited practical use, because every skill has its own goals and environment (Hochmuth and Marhold, 1978).

Why a small, general set of principles is useful

A coach cannot memorise a separate biomechanical rule for every one of the hundreds of skills across different sports. The value of reducing everything to nine generic principles is that the same principle explains performance in completely unrelated events. For example, the Principle of Balance explains both a gymnast holding a handstand and a wrestler defending a takedown; the Principle of Optimal Projection explains both a basketball free throw and a javelin throw. Learning a principle once, and then recognising it in a new skill, is far more efficient than learning a new rule for every sport.

Process principles versus product principles, in practice

• Process principles (Force-Motion, Force-Time, Inertia, Coordination Continuum, Segmental Interaction) help a coach diagnose how an athlete is generating or controlling a movement — useful while a skill is actually being performed, such as watching a bowler's run-up and arm action.
• Product principles (Range of Motion, Balance, Optimal Projection, Spin) help evaluate the result of the movement — useful when judging the outcome, such as the distance of a shot put or the flight of a cricket ball. …