Rugby is not a continuous steady state sport - it requires frequent changes in speed and intensity of effort and is therefore a predominantly
anaerobic sport

The aim of fuel mix drills is to develop a capacity to generate energy and resist fatigue, so players can perform effectively for the duration of the game. Rugby is a high intensity sport involving multiple sprints and various strength and power movements, and these activities require a rapid production of energy. This energy is produced by the anaerobic and aerobic systems, either exclusively or at the same time, hence the term fuel mix

The energy systems do not work in isolation - more often than not players will rely on a fuel mix of anaerobic and aerobic energy

The intensity and the duration of activity determines the extent to which each energy system is used. Match analysis tells us that at elite level, ball in play activities last on average 18 seconds, with a range of 5 - 63 seconds, and are performed with high intensity effort.

With multiple-sprint, strength, and power activities dominating, our preferred mode of conditioning for rugby is fuel mix training.

Energy Supply

Energy for competition is supplied via 3 pathways - anaerobic 1, anaerobic 2 and aerobic:-

1. Anaerobic 1 is termed the phosphagen system and provides short term energy for high intensity activities i.e. lineout lift.
2. Anaerobic 2, termed glycolysis, has a greater part to play and fuels most high intensity plays during a game, and produces lactic acid as a by product.
3. Aerobic energy can only supply the muscles during low to medium intensity play such as during stoppages or walking and jogging to get into position, and facilitates recovery.

As soon as intensity and duration of play reaches a certain threshold, anaerobic sources become predominant

Aerobic fitness is still an important component of the total rugby fitness programme. Aerobic training is very beneficial during active rest periods, for recovery sessions, fat burning, and for injured players who cannot perform high intensity training.

A sound aerobic capacity is required to possess health related fitness, and provides a platform for fuel mix conditioning, but should not be emphasised at the expense of strength, power and speed