Mittuniversitetet

INTRODUCTION: During or shortly after strenuous exercise, some individuals may exhibit exercise-induced bronchoconstriction (EIB) (1). Training in sub-zero temperatures, where the inspired air is cold and dry, can exacerbate the physiological stimuli that give rise to EIB and accentuate lung injury (2). To date, little is known about the training factors, such as duration and modality of exercise that result in airway damage in cold environments. Here, we aimed to examine the influence of exercise duration in cold on lung function and EIB incidence among healthy individuals.

METHODS: Eighteen healthy, non-asthmatic, physically active volunteers (males/females: 14/4, age: 29.4 ± 5.9 years old, maximal oxygen consumption [V̇O2max]: 61.3 ± 8.7 ml/kg/min) who had never competed at the elite level, completed two moderate-intensity (60% V̇O2max) climate chamber running trials at -15 ºC lasting for 30 and 90 min in a randomized cross-over design. Impulse oscillometry (IOS) was conducted before, 12, and 50 min post-trials to assess resistance at 5 and 20 Hz as well as reactance at 5Hz. Forced expiratory volume in 1s (FEV1), forced vital capacity (FVC), and FEV1/FVC ratio were measured via dynamic spirometry before, 15, and 55 min after the trials. Two-way repeated measures ANOVAs were performed to determine the impact of trial and time on the percentage change of IOS and spirometry variables.

RESULTS: There were no significant effects of trial (30 min vs 90 min trial), time (pre-trial vs post-trial time points), or interaction effects for any spirometry or IOS variable. None of the participants exhibited EIB, defined as a ≥10% reduction in FEV1, at any time point (15 min after exercise: +0.37 ±1.95% for the 30 min trial and -0.25 ± 3.47% for the 90 min trial; 55 min after exercise: +0.85 ± 2.32% for the 30 min trial and +0.15 ± 3.97% for the 90 min trial).

CONCLUSION: The acute lung function responses to exercise did not differ between the 30- and 90-min trials. Additionally, moderate-intensity exercise at -15 ºC did not lead to lung function decrements or onset of EIB in healthy individuals who train regularly outdoors.

References1. Anderson, S., & Kippelen, P. (2010). Stimulus and mechanisms of exercise-induced bronchoconstriction. Breathe, 7(1), 25-33.2. Stensrud, T., Berntsen, S., & Carlsen, K. (2007). Exercise capacity and exercise-induced bronchoconstriction (EIB) in a cold environment. Respiratory Medicine, 101(7), 1529-1536.