Different lung function trajectories potentially relevant for the understanding of the natural history of chronic obstructive pulmonary disease. a) Lung function growth and development through the lifespan of a normal subject. b) Reduced maximally attained ... Different lung function trajectories potentially relevant for the understanding of the natural history of chronic obstructive pulmonary disease. a) Lung function growth and development through the lifespan of a normal subject. b) Reduced maximally attained lung function. c) Reduced duration of the plateau phase of maximal lung function. Accelerated lung function could begin in early adulthood and be d) gradual, e) episodic (e.g. exacerbations) or f) could begin in late life. None of these trajectories are exclusive. Reproduced from [16] with permission from the publisher. Alvar Agustí, and Bartolomé Celli ERJ Open Res 2017;3:00117-2017 ©2017 by European Respiratory Society