BACKGROUND AND OBJECTIVE:: METHODS:: RESULTS:: NIV during UAE increased endurance time by a mean of 91 s (95% confidence interval (CI): 10-172, P = 0.031) and reduced dyspnoea by a mean of 2.3 on the Borg scale (95% CI: 1.0-3.7, P = 0.002) compared with exercise without NIV. There was a non-significant increase in walking endurance time with NIV during exercise (119 s, 95% CI: −17 to 254, P = 0.081); however, isotime dyspnoea was unchanged compared with walking without NIV (−1.0, 95% CI: −3.0 to 1.0, P = 0.29). CONCLUSION