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Many people dismiss the cool down as a waste of time, or simply unimportant. In reality the cool down is just as important as the warm up, and if you want to stay injury free, it's vital.

Although the warm up and cool down are just as important as each other, they are important for different reasons. While the main purpose of warming up is to prepare the body and mind for strenuous activity, cooling down plays a very different role.

Why Cool Down?
The main aim of the cool down is to promote recovery and return the body to a pre exercise, or pre work out level. During a strenuous work out your body goes through a number of stressful processes. Muscle fibers, tendons and ligaments get damaged, and waste products build up within your body.

The cool down, performed properly, will assist your body in its repair process. One area the cool down will help with, is "post exercise muscle soreness." This is the soreness that is usually experienced the day after a tough work out. Most people experience this after having a lay-off from exercise, or at the beginning of their sports season.

This soreness is caused by a number of things. Firstly, during exercise, tiny tears called micro tears develop within the muscle fibers. These micro tears cause swelling of the muscle tissues which in turn puts pressure on the nerve endings and results in pain.

Secondly, when exercising, your heart is pumping large amount of blood to the working muscles. This blood is carrying both oxygen and nutrients that the working muscles need. When the blood reaches the muscles the oxygen and nutrients are used up. Then the force of the contracting (exercising) muscles pushes the blood back to the heart where it is re-oxygenated.

However, when the exercise stops, so does the force that pushes the blood back to the heart. This blood, as well as waste products like lactic acid, stays in the muscles, which in turn causes swelling and pain. This process is often referred to as "blood pooling."

So, the cool down helps all this by keeping the blood circulating, which in turn helps to prevent blood pooling and also removes waste products from the muscles. This circulating blood also brings with it the oxygen and nutrients needed by the muscles, tendons and ligaments for repair.

The Key Parts of an Effective Cool Down
Now we know what the cool down does and why it is so important, lets have a look at the structure of an effective cool down. There are three key elements, or parts, which should be included to ensure an effective and complete cool down. They are:

Gentle exercise
Stretching
Re-fuel

All three parts are equally important and any one part should not be neglected or thought of as not necessary. All three elements work together to repair and replenish the body after exercise. Fuel up. Eat a light snack at least 30-60 minutes after your workout to help your body replace its energy stores and start repairing the body. Experts generally recommend something with both carbohydrates and protein such as yogurt, a smoothie or a half of a turkey sandwich. You should also make sure you drink plenty of water after your workout as well.

Sample Cool Down Routines
To follow are two examples of effective cool downs. The first is an example of a cool down used by a professional athlete. The second is typical of someone who simply exercises for general health, fitness and fun.

Example 1: - For the Professional
10 to 15 minutes of easy exercise. Be sure that the easy exercise resembles the type of exercise that was done during your work out. For example, if your workout involved a lot of running, cool down with easy jogging or walking.
Include some deep breathing as part of your easy exercise to help oxygenate your system.
Follow with about 20 to 30 minutes of stretching. Static stretching and PNF stretching is usually best.
Re-fuel. Both fluid and food are important. Drink plenty of water, plus a good quality sports drink. The best type of food to eat straight after a work out is that which is easily digestible. Fruit is a good example.

Example 2: - For the Amateur
3 to 5 minutes of easy exercise. Be sure that the easy exercise resembles the type of exercise that was done during your work out. For example, if your workout involved a lot of running, cool down with easy jogging or walking.
Include some deep breathing as part of your easy exercise to help oxygenate your system.
Follow with about 5 to 10 minutes of stretching. Static stretching and PNF stretching is usually best.

What are the benefits of a cool down?
An appropriate cool down will:
aid in the dissipation of waste products - including lactic acid reduce the potential for DOMS
reduce the chances of dizziness or fainting caused by the pooling of venous blood at the extremities
reduce the level of adrenaline in the blood
allows the heart rate to return to its resting rate

PNF Stretching

PNF stretching (or proprioceptive muscular facilitation) is one of the most effective forms of flexibility training for increasing range of motion.

PNF techniques can be both passive (no associated muscular contraction) or active (voluntary muscle contraction). While there are several variations of PNF stretching, they all have one thing in common - they facilitate muscular inhibition. It is believed that this is why PNF is superior to other forms of flexibility training.

Both isometric and concentric muscle actions completed immediately before the passive stretch help to achieve autogenic inhibition - a reflex relaxation that occurs in the same muscle where the golgi tendon organ is stimulated. Often the isometric contraction is referred to as 'hold' and the concentric muscle contraction is referred to as 'contract'.

A similar technique involves concentrically contracting the opposing muscle group to that being stretched in order to achieve reciprocal inhibition - a reflex muscular relaxation that occurs in the muscle that is opposite the muscle where the golgi tendon organ is stimulated.

Using these techniques of 'contracting', 'holding' and passive stretching (often referred to as 'relax') results in three PNF stretching techniques. Each technique, although slightly different, involves starting with a passive stretch held for about 10 seconds.

For clarity and to compare each technique, think of a hamstring stretch in the supine (on back, face up) position for each example. The athlete places one leg extended, flat on the floor and the other extended in the air as close to right angles to the body as possible.

Hold-Relax
A partner moves the athlete's extended leg to a point of mild discomfort. This passive stretch is held for 10 seconds.

On instruction, the athlete isometrically contracts the hamstrings by pushing their extended leg against their partner's hand. The partner should apply just enough force so that the leg remains static. This is the 'hold' phase and lasts for 6 seconds.

The athlete is then instructed to 'relax' and the partner completes a second passive stretch held for 30 seconds. The athlete's extended leg should move further than before (greater hip flexion) due to autogenic inhibition activated in the hamstrings.

Contract-Relax
A partner moves the athlete's extended leg to a point of mild discomfort. This passive stretch is held for 10 seconds.

On instruction, the athlete concentrically contracts the hamstrings by pushing their extended leg against their partner's hand. The partner should apply enough force so that there is resistance while allowing the athlete to push their leg to the floor (i.e. through the full range of motion). This is the 'contract' phase.

The athlete is then instructed to 'relax' and the partner completes a second passive stretch held for 30 seconds. The athlete's extended leg should move further than before (greater hip flexion) due to autogenic inhibition activated in the hamstrings.

Hold-Relax with Opposing Muscle Contraction
A partner moves the athlete's extended leg to a point of mild discomfort. This passive stretch is held for 10 seconds.

On instruction, the athlete isometrically contracts the hamstrings by pushing their extended leg against their partner's hand. The partner should apply just enough force so that the leg remains static. This is the 'hold' phase and lasts for 6 seconds. This initiates autogenic inhibition.

The partner completes a second passive stretch held for 30 seconds, however the athlete is instructed to flex the hip (i.e. pull the leg in the same direction as it is being pushed). This initiates reciprocal inhibition allowing the final stretch to be greater.

Here are some other general guidelines when completing PNF stretching:

1. Leave 48 hours between PNF stretching routines.

2. Perform only one exercise per muscle group in a session.

3. For each muscle group complete 2-5 sets of the chosen exercise.

4. Each set should consist of one stretch held for up to 30 seconds after the contracting phase.

5. PNF stretching is not recommended for anyone under the age of 18.

6. If PNF stretching is to be performed as a separate exercise session, a thorough warm up consisting of 5-10 minutes of light aerobic exercise and some dynamic stretches must precede it.

7. Avoid PNF immediately before, or on the morning of competition.