The principle of 'overload' states that the body adapts to the training stress or stimulus if it is worked harder than normal or longer than normal. If overload is featured gradually and regularly, then the body adapts so that the increased stress can be tolerated.
Improvements and adaptations cannot occur without an overload in effort or intensity of sessions. If the training effort or intensity is low, then detraining could occur (Izquierdo et al, 2007). The diagram below shows that if the overload is applied and enough recovery given between training sessions then adaption and improvement are achieved.
However, if overload is applied and adequate recovery is not provided, fatigue occurs (Bompa 2000, 2005). It is important that any overload is applied in a gradual and progressive manner and recovery time is adequately planned. The FITT principles discussed previously can be used to manipulate the overload placed on the player.