Ninety minutes of sprints, cuts, tackles and decelerations. Or three hours of lunging side to side on clay, serving over and over. You walk off feeling like you gave everything — and 48 hours later you find out exactly how much. Legs like concrete. A first step that's half a beat slow. A brain that reads the play a moment too late. That gap between the final whistle and feeling sharp again comes down, in large part, to two cellular control systems: the NRF2 and mTOR pathwa