Alright well what happens is weed is a bronchial dilator. Thats how it treats asthma, during an attack when the airways are inflammed, it opens the lung volume back up and allows oxygen in. Well if you apply that to aerobic exercise its the same thing. It allows more air into your lungs, which puts more oxygen in the blood, increasing blood flow to muscles.

Straight up it works. And the only reason I found this out is because I'm a huge stoner and pretty much blaze b4 everything. After finding this out, Ive asked around and read that a lot of body builders and swimmers like to blaze for the same reasons. Bobybuilders that smoke actually build muscle mass easier.