For the record, people saying "This is stupid, they're spartans not ninjas."
Well to put it simply, Yes, they are ninjas.
No of course they're not ninjas smartass, but don't base what you know off of the game... maybe the book.
Spartans are incredibly fast, strong, and have capabilities of jumping higher than 2 metres in the air, doing some crazy-ass aerobics, as seen in the chieftain battle.
It isn't seen much in the games because, well, fighting with a spartan is mostly used with guns, and in a FPS, you don't really get the chance to do aerobics all over your enemies.
The only other time this has been shown is the Halo Wars Cutscene: Monsters, where the spartan does the varial backflip over the elite while shooting with with an SMG.
Spartans ARE that capable, just because you haven't seen it in the game, doesn't mean they can't do it.
/Rant