When a person takes part in exercise, their body systems provide energy for these activities. After regular exercise participation, these systems adapt to improve exercise performance.
There are two elements to analyse when looking at effects of exercise.
Immediate/short term effects of exercise relates to what happens to your body systems as soon as you start exercising and shortly after.
Long term effects of exercise relates to what happens to your body systems over a period of time. For example your 8 week personal fitness programme.
Adaptation: The changes experienced in the body's systems as a result of long term training.