it all depends on the physical fitness of the body. A trained person does not need a second wind. He is basic enough. For beginners, the second wind opens when the primary adaptation of the body muscles during stress occurs.
First) Over time, muscles are cleared from movement, and blood thinns from an increase in acidity due to an increase in the amount of carbonic acid caused by an increase in the proportion of carbon dioxide due to shallow breathing. We can call the second breath a state when, for the above reasons, the energy consumption in the body decreases. Second) After 40 minutes, glucose ends and energy is taken from the breakdown of fats. We can also consider the appearance of this new source of energy as the second breath. It is better to focus not on the second breath, but on endless endurance at the expense of a pure organism. People run rogaining, so it's possible. https://m.vk.com/wall161608263_88
The so-called "second wind" exists, but scientists have not yet come to a consensus regarding the nature of this phenomenon. There are several hypotheses:
There may be a combination of the above factors. But the fact that professionals practically do not have any second breath, and this condition is more characteristic of those who are not very well prepared, still makes the second point about the efficient use of oxygen and lactic acid more realistic.