It's hard to be tactical when you're blinded by sweat and breathing like a train but boxers have to be fit enough to fight and think at the same time. In controlling Russian giant Nikolay Valuev for 12 rounds, and becoming WBA heavyweight champion in the process, David Haye has proven he's one of the best fighters in the world at doing just that.

So how does he prepare to go the distance? 'The first round is the toughest because people rush you and you've got to be mentally switched on,' says Haye. Then it's a question of being fit enough to move better than your opponent and land more quality punches than he does.

'It's not enough just to have strong muscles. Boxing is an explosive sport and a boxer needs to increase the speed of contraction in his muscles to get a powerful punch.'

Rotational core strength is vital when producing punching force because knockouts come from movement as much as muscle, while rock-solid abs also soak up an opponent's body blows and pack an even bigger punch.

On the right, you'll find the workout he uses to get in knockout shape.

For more cracking boxing features, subscribe to Men's Fitness. We'll give you three issue for £1.