Last summer I used the electronic cig for three months and quit regular smoking during that time. I regularly exercised before, during, and after my e-cig trial. a few weeks into using the vape, I noticed tightness in my chest that would persist whenever I exerted myself in any way. I could barely jog a quarter mile without feeling winded, with a burning sensation in my chest. These symptoms had been totally nonexistent before I used the vape, despite my frequent smoking. I regularly ran 3 or more miles without stopping. At first I did not attribute the breathing problems to the vape; I was certain the opposite would be true. My symptoms become very troubling, and other things like migraines, achiness and stiffness developed concurrently. I didn't know what to make of it all, and I considered disorders from Lyme's disease to fibromyalgia to COPD. That's how bad it was. As chance would have it, I picked up cigarettes again after three months, and within a matter of days I noticed that the burning shortness of breath was absent when I ran. The other symptoms soon also dissappeared, though I did not connect the dots till just recently in terms of the timeline of the events. All of the above mentioned symptoms have not returned in the 8 months since. I have continued to smoke cigarettes during this time, but I would still like to quit them. I'm not saying that cigarettes are good for you, or that e - cigs were solely responsible for what I experienced. However, after reading many of the posts in this blog, It's difficult to draw any other conclusion.