Evaluation of lung function and airway impedance in response to ultra-marathon

Ultra-marathon races present a prolonged cardiopulmonary physiological stress but the magnitude, persistence, and impact of race environment on respiratory function are incompletely understood. The aim of this study is to observe the effect of ultra-marathon trail races on both lung function and airway impedance.

Fifty-seven individuals (49/8, M/F) participated in either the Courmayeur-Champex-Chamonix (CCC^®, 101.5km), Ultra Trail du Mont-Blanc (UMTB^®, 171.5 km), or the Hong Kong 100 (HK, 100 km) races. Participant demographics were measured pre-race and included: age (40.7±10.3 yrs); height (175.5±7.1 cm), body mass (69.7±8.3 kg). Spirometry, airway impedance (via forced oscillation technique, FOT), maximal inspiratory (MIP) and expiratory pressure (MEP), and exhaled nitric oxide (ExNO) were assessed before, immediately (18-4 hours after), and 188-24 hours post-race. Mixed effects analysis with Dunnett's post-hoc correction were conducted to evaluate the effects of race and time.

Results demonstrated significant effects of time for: forced vital capacity (FVC), forced expiratory flow over one second (FEV₁), peak expiratory flow (PEF), forced expiratory flow between 25-75% (FEF25-75), forced expiratory flow at 25% and at 50% (FEF₂₅ and FEF₅₀, respectively), MIP, MEP, airway reactance (X) at all frequencies from FOT (X₅, X₁₁, X₁₉), respiratory rate, and ExNO (all p<0.05). A significant effect of race was also observed for ExNO (p=0.002).

Findings indicate declines in lung function and airway impedance immediately after ultra-marathon races, some of which, persisted up to 24 hours post-race. Further investigations are required to better understand the etiology of changes in lung function following ultra-endurance events.