The cool down is the period in which the physiological processes begin to return to their original state. With repetitive motions where muscles are continuously shortening, they may have the tendency to become stiff or feel tight. Within the cool down period, holding static stretches for longer periods is beneficial to bring working muscles back to their original length.

Not only do your physiological processes have to return to their natural states, but your mind needs to come back to its natural state. After your workout, take some deep breaths, relax into some stretches, and observe the effects of your workout. Acknowledge the fact that you are doing something that is good for yourself. Taking the time to be proud of what you accomplish with each workout can make you appreciate it more and keep you coming back for more.

It is thought that stretching to cool down minimizes muscle soreness and is the best time to increase flexibility. Since your muscles are warm and are experiencing an increase in blood flow, it is not uncommon for you to feel as though the stretches you do are becoming much easier.

Take advantage of this time to both relax and enjoy the endorphin rush that often follows a good workout. Use this time to work on your flexibility and to calm your body by taking slow, deep breaths. Move deeper into your stretches. For more information on stretching for flexibility, refer to Chapter 5.

During intense periods of physical exertion, the systems of your body are stressed to their near maximums, leading to an increase in body temperature, heart rate, and blood pressure. In addition, your body also experiences a buildup of biological materials (such as lactic acid) in the muscles. Also, your body releases adrenaline and endorphins into your bloodstream. If you were to simply stop moving after your workout, the levels of adrenaline and endorphins would remain at these high levels, potentially resulting in feelings of restlessness that can cause insomnia later that night. The biological materials in your muscles are known to cause fatigue and stiffness, and a rapid decrease in body temperature, heart rate, and/or blood pressure is extremely unhealthy for anyone.

For these reasons, a cool down routine is beneficial and will help you stay well and healthy in your training. Cooling down allows your body to experience a more gradual decrease in temperature, heart rate, and blood pressure until these finally return to normal resting levels. By gently working the major muscle groups, the biological materials are actively removed from your muscles.

As you gently exercise during your cool down, your body will start releasing hormones that will counteract the adrenaline in your system, allowing you to rest and have a good night's sleep afterward. As a result of the increase in the temperature of your body tissues, the postexercise period is the ideal time for you to stretch.