As we have seen, training can be effective only if the body’s systems are put under stress.

So, there must be a suitable element of overload in any training programme. This means that we have to be able to establish the safe yet effective level that an individual should train at. This is known as the training threshold. Physical work done below this level will have little or no effect on the improvement of fitness. However, work done too far above this level can lead to injury.

KEY POINT - A training threshold rate is a safe and effective level to work at.