MANILA, Philippines ? What makes Manny Pacquiao different from other boxers of his stature?

Strength and conditioning expert Alex Ariza has a ready reply: Pacquiao always goes the extra mile ? especially now that he?s preparing for his May 2 showdown with Ricky Hatton at the MGM Grand in Las Vegas.

Interviewed by Gareth Davies of Telegraph.co.uk on Saturday, Ariza said that though many fighters gladly do some extra work for a day, they won?t do it regularly.

?Extra on the run, extra on the sprints, extra on the drills; extra everywhere,? said Ariza, who supervises Pacquiao?s roadwork and physical conditioning exercises.

In the same interview, Trainer Freddie Roach said it isn?t unusual for Pacquiao to do 24 rounds of training before even taking his lunch because, ?he likes to work.?

?Sometimes, I need to let him spread his wings and fly,? said Roach of the Pacman. ?Sometimes I need to hold him down.?