We are always in a hurry, and for some of us when we exercise it's not much different. We jump into the exercise routine hoping to warm up as we go, and we stop and rush out of the gym thinking that the body will take care of itself. But it isn't quite that way.
Each exercise session should be marked by a period of warm up and another of cold down. The warm up period is mandatory to prepare your body to the exercise to come, and to reduce the chances of injury. The best form of warm up is the one the incorporates rhythmic motions and active stretching initially at small amplitudes, increasing it as the body warms up. In the case of specific sports the athlete performs activities related to the sport but with low intensity.
The increase in the muscle temperature increases the flexibility, allowing the muscles to contract faster when compared to the same muscle without being warmed up. The blood flow must increase significantly to protect the muscles against injuries during the exercise. Other effects of the warm up include increase in metabolism, increase in cardiac frequency, increase in the transport and usage of oxygen by the body, increase in the speed conduction of the nerves, and increase in muscle contraction speed and quality.
The ideal interval for warm up is of about 5 to 10 minutes. After 45 minutes without any physical activity the body has returned to its rest temperature. As a consequence of the warm up there is an activation of the central nervous system with an improvement in the attention spam, favoring learning ability, coordination, and movement precision, crucial during training. There is a release of adrenaline, which decreases the blood viscosity, increases the activity of the enzymes, and increases the energy levels by increased the metabolism of glycogen (a form of sugar readily available in the cells of the liver and muscles).
At the end of the exercise session, the cold down period is as essential as the warm up. The cool down allows the muscles to eliminate lactic acid, a metabolic by-product that accumulates in the muscles with the exercise. The gradual decrease in the activity level during cool down helps to prevent dizziness that may happen with the sudden stop of the activity. When the exercise is suddenly stopped, the blood accumulates to the lower extremities, and does not arrive to the brain in sufficient amount leading to dizziness. The cold down is also important to assist in the normalization of the blood pressure, and to gradually relax the body structures involved in the activity. The characteristics of the cold down are similar to the warm up, prioritizing whole body exercises with duration of 5 to 10 minutes in total.
In sum, the warm up and cooldown are part of your training/exercise session, offering you a safe practice, and granting longevity to the training program. Al decisions about the exercise session should always be made taking into consideration the objectives and the individuality of each person/athlete.