The ability to continually function at different work rates is an essential element of rugby fitness.   Rugby matches are made up of passages of play where you have to work at different levels.

For instance a prop might be battling with their opposite number using all types of endurance, yet at the same time a full back is running from one side of the pitch to the other as he spots the mismatch the opposition have created.  Both require endurance, just at different levels.

A ball might only be in play about 20 minutes of an 80 minute match, yet the speed at which you have to move and do stuff is really very high for a major portion of those 20 minutes.  Plus as in the example above the full back can still have to work whilst the ball is out of play (getting into position).

The ability to keep working at high intensity levels is what makes a really good athlete shine when surrounded by less capable players.  A player who is able to be just as dynamic and ferocious in the 75th minute as they were in the 5th minute can cause a lot of trouble, especially in tight matches.

Most people think endurance is just about being able to run for a long time, when in fact it can be incorporated into a lot of physiological terms.  We will be looking at anaerobic endurance, aerobic endurance and local muscle endurance (speed endurance is covered in the Speed section).

The most important of the three is probably anaerobic endurance as this incorporates a lot of the work done during a rugby match.

Aerobic endurance is of importance initially in your training and then less so, where as local muscular endurance should be trained regularly, depending on position.

Before we look at the three areas in more detail it is important to understand how we re-synthesise energy in the body (energy is never destroyed, just converts from one form to another).

1.    We supply Oxygen and Nutrients to the muscles through the blood which in turns over a lot of the energy.  The downside to this is it is slow and only useful for medium intensity work.

2.    We re-synthesise it in the muscle its self using a system called Glycolysis, which unfortunately leads to the build up of lactic acid.

3.    There is a small amount of energy stored in the muscles, some free floating and then others are attached to a phosphate molecule to form Phosphocreatine.  These supplies are very limited and get used up within a minute of starting exercise.  You cannot train the body, in the traditional sense, to have greater supplies of this.  However, some people take Creatine in order to boost the potential for greater supply.

The fitness required for rugby will have to re-sythesis energy in all the ways in order to function a your best.  Check out all the posts under the Endurance tag and you will see the different ways of training the body to re-sythesise more energy from points 1 and 2 above.