Exercise requires the integrated physiology of multiple organ systems, including the respiratory, cardiovascular, and neuromuscular systems. In a typical young healthy individual, the lungs are not thought to commonly be the limiting factor during exercise. In fact, the lungs are generally thought to be “overbuilt” such that young healthy adults generally have a ventilatory reserve when maximal exercise is reached due to the limitations in the cardiovascular system (Dempsey et al., J Appl Physiol (1985) 129(6):1235–56, 2020). However, there are situations where the lungs can be a contributing or primary factor limiting exercise in extremes of aging, pulmonary disease, and elite endurance athletes or when other factors contribute (e.g., extremely high altitude).