Why some athletes / runners can run so fast?

Part of the answer is investigating the respiratory system, its characteristics and its limits.

The overall function of the respiratory system is, essentially, to guarantee the constancy of the partial pressures of the respiratory gases at the alveolar level and therefore in the arterial blood at rest and during muscular work.

The body’s need for oxygen, especially during muscular work (think of the average oxygen consumption of a 3-4 L min. Marathoner), is covered by the functional behavior of the respiratory system.

The respiratory system consists of the lungs and the airways that allow the entry of oxygen and the expulsion of metabolic residues from within the organism. The main function of the lungs is to oxygenate the blood, through internal structures called alveoli. In the alveoli the gas exchange function is realized, in particular the oxygen diffuses from the alveolar air towards the blood while the carbon dioxide completes the inverse way.

The pulmonary ventilation mechanism allows continuous renewal of the air in the alveoli, so as to maintain constant the partial pressures of the respiratory gases in the alveolar air. This guarantees the optimal conditions for the diffusion of the gases themselves.

Physical activity induces increases in oxygen consumption and carbon dioxide production. Correlated to these metabolic changes there is an increase in pulmonary ventilation for the constant maintenance of pressure in the alveolar compartment. The increase in ventilation is mainly due to an increase in the current volume while the respiratory rate does not vary much.

VO2 max indicates oxygen uptake at the lungs, or oxygen consumption, under aerobic metabolism conditions. Data from the literature indicate that resistance training can produce an increase in VO2 max of about 10% compared to untrained individuals.

Yet the VO2 max of the marathon runners is more than about 45% of those of untrained individuals. This is partly supported by genetic factors, chest size ratio / body size greater than the ordinary and with stronger respiratory muscles. But it is also true that the long training that the marathoner undergoes produces an increase in the VO2 max to values considerably higher than 10%.

Among the various adaptations induced by resistance training, there is the ability of the organism to maintain relatively unchanged the physical chemical condition of the organic fluids, consequently there are less modifications of both the hormone structure and the acid-base structure. This greater stability promotes respiratory function (Jhonson, 1992).

The data also suggest that there is an improvement in the capacity of the inspiratory muscles to generate force and therefore pressure (Clanton, 1987), allowing the respiratory muscles to increase the aerobic capacity and therefore to have to resort less to the lactic acidic pathway (Martin, 1984) .

The morphological and structural adaptations of the respiratory system in response to training are much lower than those occurring for the cardiovascular and neuromuscular systems.

Important consideration is that respiratory capacity is not limiting on aerobic capacity in a healthy person. But various authors (Powers, 1989, Rasmussen, 1991, Williams, 1986) report that in athletes who excel in endurance tests, where there is an extreme adaptation (marathon) of the cardiovascular and muscular system to specific training, the case may occur that the respiratory system may represent a limit to aerobic power.

Good workout.



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