aka "blood doping" which generally involves extracting your own blood perhaps on a rest day and re-infusing that blood pre-workout or better yet in between sets. This will help with much faster recovery, an increase in oxygen carrying red blood cells, ability to workout longer/ harder as well as better pumps at the gym.
Best of all, it's legal, safe and FREE!
But it's gonna be a bit tricky to pull it off at a public gym I suppose.