Changes in lung function during an extreme mountain ultramarathon. An Italian group has studied the influence of an ultramarathon (330 km and 24'000 meters) on lung function. Before, during and after the course, the runners had to have a battery of lung function tests above themselves.
It showed that the lung function has increasingly decreased over the course of the competition. The work can be found under https://pubmed.ncbi.nlm.nih.gov/25262823/