Equally as important as the warm-up, the cool-down should be less intense and facilitate recovery. The cool-down does not have to be as specific as the warm-up in stimulating activity, but it does need to occur to allow the body the physiological opportunity to return to a pre exercise state. If you have performed a fast-paced workout, you need to complete it with 5 to 10 minutes of slow movements such as stretching or low-intensity exercise.

During strength training, a cool-down naturally occurs within the exercise session as a result of the intervals of work to recovery that are mixed into the workout. Although blood pressure and heart rate rise during strength bouts, they quickly return to pre exercise levels during the naturally occurring recovery periods. Stretching after strength training, however, is a good idea because the body temperature is up and the joints are lubricated.

Therefore, the body is in a good physiological state to increase muscle length. As a general rule of thumb, the more intense and exhausting the activity is, the more gradual the tapering of the cool-down period should be. 

Therefore, an active cool-down is imperative following a cardio workout. Just slow down in increments of 30 seconds to one minute until you are at a complete stop. This would be an ideal time to stretch because your body temperature is up, but your heart rate is down. The cool-down can be as simple as walking on a treadmill and performing a handful of stretches, or decreasing the intensity level of the activity you are performing with accompanying stretches. 

No matter what, do not skip the cool-down because returning to pre exercise levels is important for recovery. An indicator that your cool-down segment was not long enough or adequate to achieve recovery is continued sweating. When clients tell me that they were still sweating after a shower, I know that they did not cool down adequately.

A cool-down helps blood to continue to flow and not pool in the extremities.It also prevents significant changes in blood pressure that occur when intense exercise is stopped too abruptly. A cool-down also helps to remove metabolic waste from the muscles so that it can either be used by other tissues in other chemical processes in the body or expelled in the form of water (sweat) or C02 release (exhaling breath).

Deep, sustained stretching to improve flexibility should follow strength training and cardio workouts because warm muscle tissue accepts stretch stimuli much easier than cold tissue does. This is why stretching at the end of a workout is more advantageous than stretching at the start.

Flexibility is characterised by the ability to move joints through their normal, full ROM (Range of Motion). Adequate flexibility prevents injury and maintains correct posture and body alignment. With specific flexibility training, the muscles, tendons, and ligaments adapt by elongating and increasing their ROM. The only way to increase ROM is to alter the muscles and tendons that control the joint. In some people, these structures become extremely tight, which results in a reduction of the normal ROM.