Agreement and reliability between the two-day 6-minute incremental step test and two-day cardiopulmonary exercise test in post COVID-19 condition for assessing post-exertional malaise: The REVEAL-study - Sarah Bomans; Naomi Michotte; Imane El M’Rabet; Berenice Jimenez Garcia; Lynn Leemans; Peter Janssens; Shane Hanon; Elisabeth De Waele; David Beckwée (PLoS ONE, 2026)