Effect Of Passive Cold Exposure Prior To A Cold Air Exercise Challenge On Post Exercise Respiratory Function And Symptoms

Cold air exercise challenges (CAX) are one approach to assessing exercise induced bronchoconstriction (EIB). However it is unclear if passive exposure to cold air prior to a CAX alters the EIB response. PURPOSE: Thus, we aimed to determine the effect of passive cold air exposure, on airway function post CAX and associated respiratory symptoms. We hypothesized that cold discomfort (CD) and thermal state (TS) would increase with greater passive cold exposure, heightening airway reactivity and reducing airway function post exercise challenge. METHODS: Fourteen (8 female) healthy participants (24.7 ± 5.6 years; V̇O2max 54.6 ± 5.5 ml/kg/min) completed 3 randomized trials (0 (CON), 6 (6Min) or 12 (12Min) minutes between warmup & CAX) all with the same 15 min warm-up and subsequent 8 min run trial at -15.0 °C. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow (PEF), forced expiratory flow at 25-75% (FEF25-75), and forced expiratory flow at 50% (FEF50) were measured pre and at 3,6,10,15, & 20 min post-exercise. CD (0 to 10) and TS (-5 to +5) were measured at end of warm-up, end of interim period to confirm degree of cold stress. Respiratory symptoms were tracked 24 hours post-trial. RESULTS: CAX led to 6 EIB+ tests in 5 different participants (1 in CON, 2 in 6Min, 1 in 12Min, 1 in 6Min & 12Min) and 11 in CON, 9 in 6Min and, 9 in 12Min had FEV1 reductions of 0 to 10%. Overall (n = 14) FEV1 was reduced 4.0, 3.9, 5.4 % (p = 0.55), FVC reduced 6.5, 3.0, 4.3 % (p = 0.09), PEF reduced 5.7, 6.0, 10.3 % (p = 0.019), FEF25-75 reduced 5.6, 8.7, 11.3 % (p = 0.09) and FEF50 reduced 7.3, 9.2, 15.0 % (p = 0.07) in CON, 6Min, 12Min respectively. CD, TS and respiratory symptoms were 2.4, 4.6, 5.8 (p < 0.00); -0.7, -2.6, -3.2 (p < 0.00) and 1.5, 2.0 and 2.3 (p = 0.42) average symptoms reported for CON, 6Min and 12Min respectively. CONCLUSION: Despite significant increases in CD and TS in 6Min & 12Min conditions, prolonged passive cold exposure did not augment responses to a CAX. The PEF, FEF25-75 and FEF50 reductions in the 12Min condition may indicate that mid & small airway function are affected more with greater passive cold stress, maybe linked to CD and TS induced shivering. The trend toward more severe responses with prolonged exposure highlights how “waiting to exercise or compete” in cold weather affects respiratory function and symptoms.