I think one of the best ways phill from a purely physical exercise point would be to do repeated sets of high intensity exercise. If you were training for a fight I think varying the times and recovery periods would be a good idea.

Ive noticed that 200 m runners also run 400m 100m etc in training. So on some days it would be beneficial to train for rounds longer than what youre rounds were going to be.

Cant remember who said it but another reason those endurance runners look emaciated is the type of muscle they have is very different from the type of muscle some one generally goes after in the gym. They have long and sinewey muscle not from their body eating the muscle (protein) but from their body developing the most efficient muscle type it can for endurance sport. The amount of energy coming from protein derived from muscle is very minimal.

Although some of us wernt really made for endurance running (australian aborigines seem well made) we also wernt really made to eat mac attacks and consume as much garbage and energy dense nutrient poor crap as we do.