Rooney D, Herkenrath S, Priegnitz C, et al. - In this prospective study, researchers compared two routinely used exercise tests—50-m walk test and 6-min walk test (6MWT)—with the hypoxic challenge testing (HCT) for diagnostic accuracy in determining fitness for air travel in obese individuals. They also evaluated the diagnostic potential of perceived dyspnea as measured with the Borg scale, since this is usually recorded after walking tests. Participants included 21 obese people (10 women; aged 51 ± 15 years; BMI 36 ± 5  kg/m²). COPD was detected as the most prevalent comorbidity (n = 11). In-flight hypoxia was detected in 13 (9 with COPD) of the 21 participants. HCT—but not simple walking tests—predicted in-flight hypoxia in obese individuals. Subjective dyspnea evaluation, when recorded following 6MWT, showed good prognostic ability with an area under the receiver operating characteristic curve of 0.80 (0.55-0.93).