Cool-down should complete any training unit. In this phase the intensity decreases and, after loading, the body prepares itself for rest and repose. The heart and circulatory system are subjected to relative activity, but it is no longer a heavy burden. Cooling concludes the exhaustion phase and begins overcompensation, which, with the increase in energy accumulators, forms the basis of good training performance.
To perform the cooling phase, ergometric bicycles, treadmills or any other device that stimulates blood circulation are especially indicated, which, with the increase in irrigation of the musculature, leads to a greater transport of oxygen to process lactic acid (lactate) formed in the muscle cells. If enough oxygen is available, all the energy from lactate can be consumed, and the water and carbon dioxide produced is eliminated by urine and lungs.
Stretching exercises (flexibility) also contribute to regeneration. When muscle tone is high and flexibility is low, the ability of the muscles to support the load is reduced and, therefore, the risk of injury is lower,
Major. On the other hand, stretching reduces the tension of the musculature, which increases considerably during training and can reduce muscle flexibility between 5 and 13%, and allows the muscle to recover more quickly. A gentle stretching favours blood circulation and facilitates the breakdown of intermediate metabolism products. Finally, stretching promotes relaxation and recovery after exertion.
Muscle cells need energy to contract. The only energy that can be used directly by the body is ATP (adenosintriphosphate). Most of this chemical energy, which originates in cells through the breakdown of nutrients into their components, is transported mainly in the form of heat by the blood. Only a small part of it is stored and used by muscle cells to produce movement. However, this energy reserve is limited and rapidly consumed. Energy “recharging” can be done in two ways. For high and short duration loads, e. g. a stroke of 100 m, the muscle uses creatine phosphate for the production of ATP. In contrast, the energy used for long-term muscle work has its origin in the breakdown of carbohydrates (glucose). If the blood carries enough oxygen, energy production is aerobically produced, and oxygen is combined with intermediate metabolism products derived from decomposition. In this way, new energy is released and the ATP provisions are replenished. In endurance loads such as long distance races, almost all energy is obtained aerobically. In contrast, in the case of loads such as a long sprint, which require high amounts of energy in a very short time, glucose decomposes without the intervention of oxygen, i. e. anaerobically. In this case, through several intermediate steps, glucose is transformed into lactic acid salt, which accumulates in the cells and overacidifies the muscle. This causes the chemical bonds responsible for obtaining energy in the muscle cell to begin their activity, which translates into fatigue.
Nature has arranged this form of energy preparation because it is faster than total combustion and can operate with oxygen shortage. The excess energy is not lost, but stored in the form of ATP in lactic acid and can be released by supplying oxygen. Lactic acid is a very energy-rich intermediate product and in no case can it be considered a residual product of metabolism. This is the reason for accelerated breathing that occurs after intense loading in a short time, as in the case of a 400-metre race. In this way, the body obtains the oxygen it needs to transform lactic acid accumulated in the muscles. ATP is not only responsible for muscle tension, but also for its relaxation. Since after intense training there is little ATP available in the muscle cell, flexibility is limited. Therefore, do not attempt to increase muscle flexibility during the cooling phase and do not stretch each muscle group for more than 2 minutes.