Quantifying leg muscle deoxygenation during incremental cycling in hypoxemic patients with fibrotic interstitial lung disease: Conclusion.

Patients showed lower exercise capacity than controls (e.g., peak WR= 67±18 vs 105±20% predicted, respectively; p<0.001). The [HHb] response profile was typically S-shaped, presenting three distinct phases. Exacerbated muscle deoxygenation in patients vs controls was evidenced by: i) a steeper mid-exercise [HHb]-WR slope (0.30±0.22 vs 0.11±0.08 μmol/W, p=0.008) (phase 2), and ii) a larger late-exercise increase in [HHb] (p=0.002) (phase 3). Steeper [HHb]-WR slope was associated with lower peak WR (r=-0.70) and greater leg discomfort (r=0.77, p<0.001) in f-ILD. This article is protected by copyright. All rights reserved.