The volume of air (in liters) that can be drawn from the fully inflated lungs is called forced vital capacity (FVC); also the most important measure of air flow is the forced expiratory volume in the first second (FEV1), this is the amount of air that an individual can draw a second after starting exhalation taking the Fully inflated lungs and doing their best.
Training improves the resistance and strength of the respiratory muscles in athletes, reduces the resistance of the respiratory channels, increases lung elasticity and alveolar expansion as seen in studies where there is an expansion of lung capacities and volumes. This improvement can be quantified by spirometry.
