Proper and comprehensive athletic warm-up and cool-down protocols are essential to short-term exercise performance, as well as long-term injury prevention and general physical health. The warm-up/cool-down sequences are as important to athletic performance as the athlete's abilities in the sport itself. While each is a part of the exercise and training continuum, different principles are at play in these training phases.

A warm-up is intended to ready the athlete for either a training session or a competition. While a warm-up routine may take many forms, subject to the sport or the training goals of the athlete, the warm-up will both physically and mentally prepare the athlete for the intended task. From a physiological perspective, the first objective of the warm-up is the increased flow of blood through the cardiovascular system, preparatory to the heart being engaged in more vigorous and demanding effort. The increase in blood flow serves to make the skeletal muscles supple and more prepared to stretch. Increased blood supplied to the muscles correspondingly increases the amount of oxygen and other nutrients available to the muscles during exercise.

The start of a warm-up is a signal to the body that exercise is about to commence, a form of mental preparation. The warm-up also is a trigger to the neuromuscular system that the linkages between the nervous system and various muscle groups will be utilized shortly. While a lack of available training time and a desire to begin the substantive parts of the training or activity are the most common reasons as to why some warm-ups are not thorough, numerous sports science studies have confirmed that a thorough warm-up will reduce the rate of injury while increasing overall athletic performance.

While the intensity and the duration of a warm-up will vary due to individual circumstances, evidence that the desired increase in cardiovascular activity and an increase in internal body temperature consistent with muscle warmth is the generation of a light-to-moderate degree of perspiration. A minimal warm-up, where the athlete is not engaging in a specific or targeted activity, will generally last from eight to 10 minutes. This warm-up might include very easy jogging or vigorous walking, with a pronounced arm swing to increase the heart rate. When the warm-up is conducted in cold weather, the body may require a longer period of time to produce the desired cardiovascular and thermoregulatory effects. The athlete may conduct some sport-specific warm-up movements to provide benefits.

Once the body has been activated through a basic warm-up, the athlete may engage in a stretching program. All skeletal muscle groups are more vulnerable to strain and tearing if the muscles are aggressively stretched without a warm-up. The most effective method of stretching, the static stretch, requires the athlete to maintain the muscle structure in the extended position for between 20 and 30 seconds. It is particularly important to conduct the static stretches for the muscles that will be primarily engaged in the activity ahead.

The primary goal of the cool-down phase is to gradually reduce the level of activity achieved by the body during either training or competition. An effective cool-down program will gradually reduce the person's heart rate to its normal level, and it will assist in the efficient removal of metabolic wastes, such as lactic acid produced by the cardiovascular system. Just as importantly, a proper cool-down will ready the muscles for the next training session or activity. There is no conclusive scientific proof that cooling down necessarily reduces a condition known as delayed onset muscle soreness. This condition frequently occurs to athletes whose muscles have been subjected to a strenuous workout, with the onset of muscle discomfort not present for between 24 to 48 hours after the event. However, overall muscle health is promoted through the cool-down process whether or not the muscle subsequently becomes sore.

A simple and effective means of cooling down is to continue to exercise at a low intensity level for approximately 10 minutes for every hour of vigorous exercise, immediately at the conclusion of the primary exercise. A gap between the higher intensity levels is counterproductive to the goals of a gradual return to resting levels. A stretching routine of the same extent and intensity level to that employed in the warm-up is also useful, as the muscles are properly warm from the activity.

SEE ALSO Calisthenics; Exercise recovery; Fitness; Musculoskeletal injuries; Stretching and flexibility.