However, clenbuterol also yielded three very negative changes. First, after just four weeks, clenbuterol-treated rats were unable to maintain their normal swimming or running training intensities, while clean rodents were quite capable of continuing. Secondly, the hearts of the clenbuterol-taking, trained rats increased dramatically in size compared to the hearts of sedentary rats, but the heart expansion was probably due to the infiltration of collagen fibres into the heart walls, not an increase in heart-muscle cells. Collagen is a tough connective tissue which doesn't augment heart-muscle power but in fact stiffens the heart, potentially leading to a decrease in cardiac output. Increases in collagen may also produce cardiac arrhythmias. Thirdly, clenbuterol rats suffered from noticeable cardiac-cell degeneration.
(
http://www.pponline.co.uk/encyc/0176.htm)
You may not think you are a rat, but some people might.
Bottom line, I've done the real deal, I noticed an increased pump using it. I also noticed it made my calves cramp, and read about a lot of bad long term sides.
I have decided at my ripe old age of 26, that I may want to limit the chemicals I put into my body. Just giving this a shot for a couple weeks.
Thanks for the input you negative nancys.