Some people say that their cardio is worse when smoking weed but this isnt the case with me. I have better cardio now i smoke then i did when i didn't smoke. Now smoking cigs is a whole different story. My first muay thai class i was a smoker and i couldn't even get through the warm up let alone thai pad/bag work and sparring. But with weed its like i never even have had smoke in my lungs. Some people are different though and i know cig smokers with good cardio aswell lol. 1 cig or even 1 cigar my cardio goes to shit QUICK. I haven't smoked in 6 years though. Gross habbit.