The cool-down portion of an exercise session is important for your safety.  It allows for a gradual decrease in heart rate and blood pressure toward pre-exercise levels.  The cool-down also helps to bring the blood back to the heart.  Stopping exercise too abruptly, especially from a vigorous intensity, could increase the chances for post-exercise hypotension (blood pressure too low) from blood pooling in the legs.  Dizziness and/or fainting could result.  If the cool-down is insufficient, there is a greater likelihood for irregular heart rhythms to occur as well.  Furthermore, a proper cool-down facilitates the removal of "waste" products (lactic acid) from the exercise.

     The cool-down should last at least 5 minutes and involves gradually decreasing the intensity of exercise.  Stretching exercises, especially of the muscle groups used in the activity, can be performed when the heart rate is near pre-exercise levels.  Each stretch position should be held for 10-30 seconds and performed 2-4 times.  Stretch the muscle until you feel tension but not pain.  If pain occurs, ease off until only tension is felt.  Do not bounce during the stretch.  Bouncing can strain the muscles.  Remember to breathe while holding the stretch.

     Drinking fluids to replenish those lost during the activity should be done at this time.  It is recommended that you weigh yourself both before and after exercise to determine how much fluid you need to drink after exercise.  You should consume 20-24 ounces of fluid for each pound lost due to sweating.

     Incorporating a sufficient cool-down that includes a gradual decrease in heart rate, proper stretching techniques and adequate fluid replacement will help to ensure your safety.

Note:  Before beginning an exercise program or increasing the intensity level of a current routine a physician's approval should be obtained, especially for older adults and those at risk for or who currently have chronic health conditions.

Resources:

ACSM's Guidelines for Exercise Testing and Prescription/American College of Sports Medicine; 7th edition

ACSM's Health & Fitness Journal 12(4): 5-6, 2008

Medicine & Science in Sports & Exercise 39(2): 377-390, 2007