The major limitation to exercise performance in COPD is dynamic hyperinflation.

@article{Odonnell2008TheML,
  title={The major limitation to exercise performance in COPD is dynamic hyperinflation.},
  author={Denis O'donnell and Katherine Alexandra Webb},
  journal={Journal of applied physiology},
  year={2008},
  volume={105 2},
  pages={753-5; discussion 755-7}
}