Work, power and energy

When investigating the biomechanics of human movement, the term “work” is used to describe the relationship between the net forces applied to a body and its subsequent movements. However, some movements may require the work to be carried out within a relatively short period (e.g. shot-put), while others may allow the work to be conducted over an increased timeframe (e.g. walking stance phase). To appreciate the mechanical differences between such tasks, scientists may also be interested in describing the rate at which an athlete performs the work; that is, they may wish to evaluate the athlete’s power. This section describes the differences between positive and negative mechanical work and summarises the various sources of energy that provide the potential for work to be performed. Although when used in the context of human movement, the term “energy” can be limited to describing the chemical energy involved in muscle contraction, this section highlights the importance of mechanical energy sources such as potential energy and kinetic energy to human movement.