In a person with muscular dystrophy, which statement regarding pulmonary function is true?

In individuals with muscular dystrophy, respiratory function is often compromised due to the weakening of the muscles involved in respiration. Inspiratory capacity refers to the maximum amount of air that can be inhaled after a normal expiration. In this condition, the respiratory muscles may not function adequately, resulting in a reduced ability to take deep breaths. This inability to effectively expand the thoracic cavity typically leads to a low inspiratory capacity.

In contrast, vital capacity, or the total amount of air that can be exhaled after a full inhalation, may actually be reduced rather than increased due to muscular weakness, which affects both the inhalation and exhalation phases. Total lung capacity could also be impacted, typically showing reductions rather than remaining unchanged. As for expiratory volume, since the muscles required for expiration (such as the diaphragm and abdominal muscles) are weakened, there is often a decrease in the amount of air that can be forcefully exhaled.

Thus, the assertion regarding inspiratory capacity being abnormally low accurately reflects the physiological consequences of muscular dystrophy on pulmonary function.