After a strenuous cardio workout, your body feels heavy and hot as your blood continues to stream strongly throughout the different parts of your body. When after an exercise you proceed to dry yourself with a fan or take a shower at once, your muscles might find it a bit difficult to relax. It is important to cool down your body after you exercise.
One benefit of post-exercise cool downs is that it prevents adrenaline dizziness. Heavy workouts cause the leg blood vessels to expand to bring more blood into the legs and feet. Once you stop exercising without any cool down, the heart rate slows down quickly, leaving a large amount of blood stuck in the lower body that may cause dizziness due to the lack of blood in the upper body and too much adrenaline.
Most trainers do not design cool downs to prevent muscle soreness and injury. Instead, it was designed to ensure the blood flow in the body balances out after a workout.
A good proper cool down may be walking from the treadmill to the locker room or just performing a good post-exercise stretch. However, unlike the initial stretching before you exercised, a cool down stretch is slower and more concentrated in ensuring that all blood blocks and circulation continues unhampered throughout the body.