Rowe A, et al. - Using eucapnic voluntary hyperpnea (EVH), researchers assessed circadian variability in exercise-induced bronchoconstriction (EIB) among 14 recreationally-active males with mild to moderate asthma and 9 healthy controls enrolled in this study. Using randomization, the participants were asked to first complete either an AM (07:00–08:00) or PM (17:00–18:00) EVH challenge, followed by the alternate test 34 h to 7 days later. In the asthma cohort, 3.58 ± 0.95 L and 3.62 ± 0.87 L were the minimum observed post-EVH FEV₁ in AM and in PM tests, respectively, corresponding to a 15.0 ± 15.3% vs 14.9 ± 14.7% attenuation from baseline, respectively. Findings revealed that EIB was not influenced by time-of-day in mild to moderate asthma, when baseline pulmonary function was similar.