In terms of running the word endurance can be understood to have several meanings. For some the definition would describe a running distance, on track this is 800m and above; on roads tryical distances are from 5km through to marathon. It is also defined as a component of fitness which is fundamental for any runner to offset fatigue or to be able to perform when fatigued. The 2 basic types of endurance are: Aerobic Endurance (muscular contractions take place using oxygen to release energy from the muscle fuels), Anaerobic Endurance (muscular contractions take place without oxygen using the stored energy available in the muscles). It is helpful to understand the energy systems available and how they are used.

Alactic System: this is the start up energy system and used for high intensity and maximal speed running for up to 10 seconds. It does not require oxygen and waste products are not produced. To develop this energy system maximal intensity efforts for a very short duration with longer recovery should be practised.

Lactate System: sometimes referred to as the linking system. It can operate without oxygen, uses fuel stores but produces both lactate and acid. This fuel system is capable of operating for up to 3 minutes.  This energy system can be developed using repetition/interval training over moderate duration (under 3 minutes) at intensities of 80% and above, with relatively short recovery periods.

Aerobic System: this is the sustained energy system using both oxygen and fuel stores. This energy system can be developed by continuous running including fartlek and also reps/intervals of longer duration/distance with lower intensity, typically 50% – 75%. For repetition/interval training the recovery periods will be shorter.

It should be noted that all energy systems operate together; it is the emphasis that is different depending upon the duration and intensity of the running.