What happens to VO2max as disease severity increases in CF?

What happens to VO2max as disease severity increases in CF?

• A. Increases
• B. Remains unchanged
• C. Varies widely
• D. Decreases

Answer: (D)

VO2max is the maximum rate at which the body can take in, transport, and use oxygen during intense exercise, reflecting both delivery by the lungs and heart and utilization by the muscles. In cystic fibrosis, as disease severity increases, lung function worsens due to airway obstruction, mucus plugging, and structural tissue damage, which lowers ventilatory capacity and impairs gas exchange. This leads to reduced oxygen delivery to the blood and greater work of breathing, causing earlier fatigue during exercise. At the same time, progressive CF often brings muscle deconditioning and nutritional deficits that diminish the muscles’ ability to extract and use oxygen (lower oxidative capacity). Because VO2max depends on both oxygen delivery and utilization, worsening CF reduces the body's maximal aerobic capacity.

VO2max is the maximum rate at which the body can take in, transport, and use oxygen during intense exercise, reflecting both delivery by the lungs and heart and utilization by the muscles. In cystic fibrosis, as disease severity increases, lung function worsens due to airway obstruction, mucus plugging, and structural tissue damage, which lowers ventilatory capacity and impairs gas exchange. This leads to reduced oxygen delivery to the blood and greater work of breathing, causing earlier fatigue during exercise. At the same time, progressive CF often brings muscle deconditioning and nutritional deficits that diminish the muscles’ ability to extract and use oxygen (lower oxidative capacity). Because VO2max depends on both oxygen delivery and utilization, worsening CF reduces the body's maximal aerobic capacity.