Inspiratory Reserve Volume (IRV) is the maximum amount of air that can be inhaled after a normal inhalation. It represents the extra capacity of the lungs to take in air when needed, such as during exercise or physical exertion. IRV is an important component of lung function and is measured during pulmonary function tests. Understanding IRV helps assess respiratory health and can indicate how well the lungs are functioning in various conditions, such as asthma or chronic obstructive pulmonary disease (COPD).