So, I did shoulders and bi's yesterday. Took the third packet on Thursday and yesterday during work out had really great pumps. I don't know if its had time to build up in my system-alien blood ya know-or if its just when I do bi's. However, didn't keep the pump very long. Literally within an hour and a half or so, it was gone. And I am not getting that pumped feeling 8 hours later like many have reported. I gonna keep trying though.