Effects Of A Cooldown On Exercise-induced Bronchoconstriction

PURPOSE: No studies have observed how a cooldown affects the airways of people with exercise-induced bronchoconstriction (EIB). The objective of this study is to determine the effects of a cooldown on the severity of airway narrowing in adults with EIB. We hypothesized that a cooldown through a decremental decrease in workload would reduce airway narrowing in adults with EIB. METHODS: Adults with EIB (n = 3; age, 23.3 ± 0.7 yrs; BMI, 27.5 ± 1.8 kg/m2) and non-EIB controls (CON) (n = 7; age, 32.9 ± 3.2 yrs; BMI, 25.7 ± 1.4 kg/m2) completed a high-intensity cycle ergometry bout on three separate occasions. The exercise bout consisted of six minutes of exercise at 85% peak power. Each bout was followed by one of three interventions: 1) spontaneous recovery consisting of seated relaxation (SR), 2) cooldown through a gradual reduction in workload for 10 minutes after the bout, or 3) mimic ventilation of the tidal volume and breathing frequency achieved during the cooldown trial, without pedaling. Maximal forced exhalations (MFEs) were performed before exercise and every two-minutes after the exercise bout for 20 minutes. The maximal post-exercise decrease in forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and peak expiratory flow (PEF) were compared within- and between-subjects. RESULTS: During the SR trial, the maximum %-decrease in FVC after exercise was significantly greater in the EIB than CON subjects (-1.56 ± 1.05 vs. -12.16 ± 1.60% for CON vs. EIB, respectively; P < 0.01). Significant differences were also seen in FEV1 between the groups during the SR trial (-4.89 ± 2.75 vs. -21.18 ± 4.20% CON vs. EIB, respectively; P < 0.05). No changes to FVC and FEV1 were seen between trials in the CON group. In the EIB group, maximal %decrease in FVC and FEV1 during the SR trial (-12.16 ± 1.60 and -21.18 ± 4.20% for FVC and FEV1, respectively), cooldown trial (-17.67 ± 7.40 and -26.05 ± 8.94% for FVC and FEV1, respectively) and mimic trial (-9.29 ± 3.01 and -22.94 ± 6.02% for FVC and FEV1, respectively) were not significantly different. CONCLUSIONS: The maximal decrease in airway caliber was not significantly different between the different intervention trials in both the CON and EIB groups. Thus, we concluded that the gradual cooldown performed after a high-intensity exercise bout does not reduce airway narrowing in those with EIB.