The U.S. military has already tried basically this twice. Once back in the late 40's to for fighter pilots, and again in the 90's, a practice they called "Bloo

The U.S. military has already tried basically this twice. Once back in the late 40's to for fighter pilots, and again in the 90's, a practice they called "Blood loading". https://en.wikipedia.org/wiki/Blood_doping https://en.wikipedia.org/wiki/Blood_doping