What happens to peak work capacity in CF during disease progression?

What happens to peak work capacity in CF during disease progression?

• A. Increases
• B. Unchanged
• C. Decreases
• D. Fluctuates

Answer: (C)

Peak work capacity in CF declines as the disease progresses because the lungs become more impaired and the body spends more energy just to breathe during effort. Worsening airway obstruction and mucus plugging reduce airflow and gas exchange, so ventilatory limits are reached earlier and the respiratory muscles fatigue faster during high-intensity activity. At the same time, systemic factors like malnutrition and muscle deconditioning weaken peripheral muscles, making it harder to sustain or reach a high work rate. Combined, these changes lower the maximum work someone can perform. Day-to-day fluctuations can occur with infections or nutritional status, but the overall trend with progression is a decrease in peak work capacity.

Peak work capacity in CF declines as the disease progresses because the lungs become more impaired and the body spends more energy just to breathe during effort. Worsening airway obstruction and mucus plugging reduce airflow and gas exchange, so ventilatory limits are reached earlier and the respiratory muscles fatigue faster during high-intensity activity. At the same time, systemic factors like malnutrition and muscle deconditioning weaken peripheral muscles, making it harder to sustain or reach a high work rate. Combined, these changes lower the maximum work someone can perform. Day-to-day fluctuations can occur with infections or nutritional status, but the overall trend with progression is a decrease in peak work capacity.