Individuality. People react to the same training stimulus in different ways. The main reasons are: genetic; initial fitness levels; maturity.
Adaptation. When you train regularly, physiological changes take place over time to make you more effective and efficient.
Overload. To improve your fitness, you must continually progress the work you perform.
Work / Play vs Rest / Regeneration. Although it is important that training load is progressive, time for rest and regeneration is just as important.
Specificity. Fitness is specific and your training must relate to the demands of the game you play.
De-training. Any prolonged lay-off from training will be accompanied by a drop-off or de-training of fitness levels. So, you should undertake a reconditioning programme before you return to full training / play.
