There are 3 types of exercise: · Sprinting e.g. explosive running - 100 m sprint · Endurance events e.g. marathon running, triathlon · Resistance e.g. weight lifting

Most activities come into one of these types and the source of energy for these varies:
In short duration sprint exercise the body uses instant energy sources (e.g. glucose) as its primary fuel.
In endurance sports, the body initially uses short term, instant energy (glucose), but the body also draws on its stored energy sources (glycogen and fat) to ensure peak performance can be maintained over extended periods of time.
Intermittent exercise
For many sports – especially team sports such as football, rugby, hockey and netball – a combination of exercise types are involved.
Football is a combination of sprinting and endurance, together with walking and some standing still.
These sports are known as ‘intermittent exercise’ and require both immediately available and stored energy reserves.
Regular sports participants should remember that whatever type of exercise they do, performance can be improved by tailoring the diet to ensure it meets the energy needs of the body.

Keeping glycogen levels topped up and readily available is vital to sporting performance. It’s simple – when you run out of glycogen, you will quickly run out of energy. This is particularly important in endurance events, such as long distance running, as the lower your muscle glycogen content, the shorter the time to exhaustion. This means you’re likely to suffer from early fatigue and impaired performance.