your red blood cells carry oxygen to your muscles. so basically the higher your red blood cell percentage the better your muscles will operate under stress. in layman s terms, the more red blood cells you have the faster you re going to ride a bike. so what was the doctor s solution to raising those levels? yeah, a couple months before, maybe a month and a half before my first tour de france, it was epo. under uci rules at the time, riders were allowed a hematocrit level of 50% but no higher. tyler hamilton said doctors would tell riders what their glow time was with different drugs. you were given the limits on what product would how long you d glow for. how long you d test positive for. so as long as you played by what the team doctors told you, it