Short bouts of whole-body warm-up exercise were shown to protect airways by attenuating bronchoconstriction in response to subsequent intense exercise in people with exercise-induced bronchoconstriction (EIB). Whether isolated respiratory warm-up offers similar refractoriness and whether this refractoriness translates into improved exercise performance is unknown. Thus, the aim of this study was to investigate whether 1) respiratory warm-up by normocapnic hyperpnea with partial rebreathing attenuates EIB severity during subsequent exercise and, 2) whether the suggested attenuation leads to improved exercise performance. Nine subjects (6 females, 3 males; age: 25±5 years; forced expiratory volume in 1s [FEV1]: 104±15% predicted) with a history of mild EIB and a ≥10% decrease in FEV1 after a control 8-min exercise challenge (ECh) took part in this study. They were tested in 4 different conditions: Exercise after 1) no warm-up (NWU) or after 10min of respiratory warm-up at either 50% (WU50) or 70% (WU70) of maximal voluntary ventilation, or at variable intensity (30s-80%, 45s-30%, etc; WU80/30). Each warm-up was followed by an 8-min cycling ECh with dry air, followed – after 30min – by constant-load cycling to exhaustion (CL) at similar intensity and air condition. Lung function was measured at baseline, 0, 5, 10 and 15min after NWU/WU, and 5, 10, 15, 20, 25 and 30min after the ECh. Values are means±SD and compared by repeated-measures ANOVA. The maximal decrease in FEV1 after WU did not differ between conditions and never reached ≥10%. The maximal decrease in FEV1 after the ECh was -14.9±3.6% in NWU which was significantly attenuated after WU50 (-9.3±5.0%), WU70 (-7.2±5.0%), and WU80/30 (-8.6±7.5%), with no difference between warm-up conditions (p>0.05). Workload and ventilation during ECh did not differ between conditions, suggesting that the ventilatory stimulus to the bronchial system was similar. In NWU, FEV1 immediately before CL was still significantly reduced compared to baseline and WU-conditions (all p<0.05). This did, however, not translate into significant improvements in times to exhaustion and did not affect ventilation and gas exchange during CL (all p>0.05). These data indicate that intense respiratory warm-up carried out before whole-body exercise can attenuate EIB severity and improve recovery, even in the absence of significant airway narrowing acutely after warm-up. The lack of improvements in exercise performance might be due to a stronger bronchoprotection induced by the ECh, masking improvements observed with prior respiratory warm-up.