Beterbiev never runs out of gas, but all his opponents do. It's not just his cardiovascular conditioning, it is his pressure that fatigues his opponents. They exert tons of energy, while he is relaxed in the ring. This content is protected
One of the big factors is that he doesn't need to load up. Boxers waste a lot of energy throwing powershots, but Beterbiev's arm punches are powershots. If you just throw powerful arm punches all fight, you're not going to waste that much energy.
