Caffeine stimulates the alpha receptors in the heart, I believe though I could be mistaken on the details (it’s elither Alpha or Beta receptors). The end result is it will produce adrenaline which creates the fight or flight response drawing blood away from the hands, feet, and yes even the penis. From my experience taking 400-600mg caffeine in pill form and 75mg ephedrine daily, shrinkage is a big factor though only temporary. It usually goes away after 6-12hrs and a half life result of 50-100mg. Though I caution those into higher doses of caffeine and extensive execise to practice daily edging/pumping or the blood vessels more towards the head will atrophy. You can get your hard earned girth back but it may take a few weeks of edging twice a day. A Divocup does help but there is a chance it will fall off under times of stress.
Bpel: 8", Bpeg: 6", Mbeg: 5.75", Meg: 5.5", Aheg: 5.25", Heg: 4.5" - 11/18/11
Bpel: 8", Bpeg: 6", Mbeg: 5.875", Meg: 5.63", Aheg: 5.38", Heg: 4.75" - 5/18/12
Bpel:+1/4", Bpeg:6", Mbeg: 5.875", Meg:+1/16", Aheg: +1/16", Heg: +1/16" - 6/18/12