The validity and reliability of four-meter gait speed test for stable interstitial lung disease patients: the prospective study.

Background: The 4-m gait speed test is a simple functional performance measure for older adults or patients with chronic obstructive lung disease. However, limited data exist regarding these measures for patients with interstitial lung disease. We evaluated the correlation between the 4-m gait speed and 6-min walk distance tests for interstitial lung disease patients and examined their underlying physiological factors.