The body responds to exertion in a specific manner. This response can be divided into 4 stages.
Phase 1: ‘tiredness’
During the exertion phase, various mechanisms in the body are engaged, such as energy provision, the disposal of waste substances, etc.
An untrained body is quickly overwhelmed by the exertion and this manifests as tiredness. The tiredness increases systematically and the activity reserve reduces further.
Phase 2: ‘recovery’
After the exertion, it takes a while for the normal functions of the body to be restored. The energy stores in the body must be replenished.
The waste substances that have collected in the muscles must be disposed of and any damage, e.g. stressed muscle fibres, must be repaired. The performance capacity is temporarily reduced.
Phase 3: ‘super-compensation’
Recovery after exertion continues until the body has achieved its previous condition. The body strengthens a few functions so that it is better prepared for future exertion.
These improvements are called the training effect. During this phase, people can make greater efforts than previously. The phase must be used in order to build up fitness. Training in this phase will lead to improved fitness, little by little.
Phase 4: ‘reducing to original situation’
When no further exertion occurs, the accumulated reserves gradually return to their original levels.