The cool down is just as important as the workout, and just like the exercises, it must be done correctly for maximum benefit. There is nothing difficult or earth shattering here, and optimally you should spend about 20 minutes total in the cooling down phase. This will help you rid your muscles of any waste products, like lactic acid build-up, from your working muscles, your heart rate will have a chance to return back to normal, and your muscle fibers will realign after the stress endured during exercise.
The first step in the cooling down process is to rehydrate your body. Make sure you drink plenty of fluids, and sports drinks with electrolytes are the best choice, although even water will do the trick. A good way to tell if you are rehydrated is to monitor the color of your urine. Ideally, you'll want a lighter yellow urine color which signifies a well hydrated body, but if it is dark golden, you'll need to drink more.
This is the best cooling down exercise you can do for your body. Go for a good 10 minute walk at the end of your exercise session.
Although you could go for a very light jog, walking is better for you in this instance. Walking means you are no longer stressing your body in any way which allows all aspects of your body mechanics to return to normal operating procedure. A jog, no matter how light it is, still puts a bit of stress on your joints, and after a good exercise session, you don't need any more stress on joints. Plus, walking more effectively reduces your body temperature and your blood pressure, which is exactly where you want to be during a cool down.
So take a walk, allow your body to relax and cool, which will also help remove waste products as well.
After your walk when your muscles are still warm, do some light stretching. Again, nothing hard core here, and this is the best way to realign all of your muscle fibers. Stretching is particularly helpful if you have a sore muscle, because during the cool down is the time to stretch it out. By doing this you'll speed blood flow to the affected muscle and that aids in both healing and flushing out waste.
Do about 10 minutes or so of stretching, let your body relax and you'll be good to go.
Drink a Protein Shake/Smoothie
Your body is in its maximum nutritional absorption state during your cool down period. After you cool down, drink a protein shake or a protein smoothie. The protein will speed right to your muscles and begin to nourish and rebuild them for the next day's work out.
A good recipe is 1 gram of protein for every 4 grams of carbs. If you have a pre-mixed protein powder, that's an even better solution. And here's a tip- If you don't have a protein drink handy, drink a glass of chocolate milk instead. Granted, it's higher in sugars but the chocolate has a lot of protein in it, and if you drink skim chocolate milk, you'll limit your fat caloric intake.
Just remember, for optimal results, the cool down must be done after every workout. Don't skimp on the time or skip this routine altogether. The cool down is the best time for your muscles to begin rebuilding, so it is very important to follow this regimen every time.