Cigarette smoking: an underused tool in high-performance endurance training (ncbi.nlm.nih.gov)

First all, I'm surprised in this day age that someone is publishing anything that promotes cigarette smoking. This is just asking to get blackballed by the anti-smoking Gestapo.

Secondly, the benefits of cigarette smoking, as outlined here, explains why there's a lot of smokers in high-stress jobs.