The Effect of High Intensity Interval Exercise in High / Low Temperatures on Exercise-Induced Bronchoconstriction (EIB) in Trained Adolescent Males

BACKGROUND Exercise-induced bronchoconstriction (EIB) describes airway narrowing that occurs in association with exercise. Exercise in hot and cold environments has been reported to increase exercise-induced bronchoconstriction (EIB) in subjects with asthma. However, to our knowledge, the effect of hot and cold environment on pulmonary function and EIB in trained males has not been previously studied. The main goal of this research was to examine the influence of environmental temperature and high intensity interval exercise on pulmonary function in trained teenage males. Also, this study sought to assess the influence of exercise and environmental temperature on EIB. MATERIALS AND METHODS Thirty trained subjects (mean age 16.56±0.89 yrs, all males) underwent high intensity interval exercise testing (22 minutes) by running on a treadmill in hot and cold environments under standardized conditions (10 °C and 45 °C with almost 50% relative humidity in random order in winter and summer). Lung function (flow volume loops) was measured before and 1, 5, 15, 30 and 60 min after the exercise by digital spirometer. Data was analyzed using SPSS software and P < 0.05 was considered significant. The diagnosis of EIB was made by 10% fall in FEV1 post-exercise. RESULTS The post-exercise maximal reduction in forced expiratory volume in 1s (FEV1), peak expiratory flow (PEF) and average forced expiratory flow rate over the middle 50% of the FVC (FEF25-75) increased significantly compared to pre-exercise at 10 °C with almost 50% relative humidity (cold air). The obtained values were: -15.93(15min post-exercise), -22.53 (1 min post-exercise) and -18.25%(5min post-exercise). Post-exercise maximal reduction in FEV1, PEF and FEF25-75 increased significantly compared to pre-exercise value at 45 °C with almost 50% relative humidity (hot air). Obtained values were: -10.35 (1 min post-exercise), -9.16 (1 min post-exercise) and -7.39 (5 min post-exercise). Changes in FEV1, PEF and FEF25-75 reduction in cold air was significantly greater than in hot air (P < 0.05). Maximal prevalence of exercise-induced bronchoconstriction (EIB) in cold and hot air was 60% (18 of 30 subjects) and 40% (12 of 30 subjects), respectively. CONCLUSION This study demonstrated that pulmonary function in hot and cold air was influenced by temperature (in the same relative humidity (50%) and also high intensity interval exercise. Prevalence of EIB after high intensity exercise in hot and cold air increased in trained adolescent males; however, these changes in cold air were greater than in hot air among trained adolescent males. Therefore, results of this study suggest that adolescents (although trained) should avoid high intensity (95% maximal heart rate) exercise in winter (extremely low temperature) and summer (extremely high temperature) to prevent EIB.