Do any of the biped dragons stretch their fore arms, because them having their arms like that one would think that they would get cramp.

Also when they run they spend most of their time floating, except the time when they decide to put one of their feet down to stop falling on their face. :P

there is only one type of biped dragon that doesnt do that and they belong to the army of the dragon crew, they run, walk and whatever with their arms down,

Furox and the purple dragons were seen holding their forearms up to make a threatening stance with their claws showing, but the other bipeds don't seem to use their arms for anything. Propheci of course, used his arms to try and hang on when he fell in "Track of Doom", but I think that's the only time we've seen a biped dragon do something constructive with their forearms.

yeah i havent seen any of them use their arms much

Now that I think about it I havent seen thier arms used much either.

The animators may intentionally be avoiding having the bipeds use their arms to keep them distinct from humans. I don't think the creators of the show want the dragons to come off as looking anthropomorphic even in the slightest. It seems to keep them more animal-like if they don't use their arms.

Today I was watching Animal Park about the animals in a english safari park and I was watching the wallabies, and thought that they look like the biped dragons, except from the fur, they little ears, really cute faces and their bounce.
And then I had a thought, maybe the biped dragons use they fore arms to hold large chunks of food while they eat.

I just rememberd an eppisode when a Biped uses their arms in a big way! In return of drakkus PT2 Tyrannis Pax uses his/her arms to throw Abandonn through a rock wall or something. Of course he uses his normal arms and his extra arms but you get my point.

Oh, wow! How could I ever forget my favorite battle dragon T. Pax! I think I've been working too hard lately. My mind is blanking on something so obvious. :D

Yes, T. Pax doing the Olympic style hammer throw with Abandonn is a classic moment for sure, and one of the just plain coolest moves a dragon makes in the show. (Though Beau's trademark spinning tail-trip move is a close second. :)) And after the toss, T. Pax then carries Mortis to safety in his hands. What a nice dragon. ^_^ I bet Connor gave T. Pax a few extra Draconee-Yum bars that night for sure.

Im not sure that I would want to see the size of the bar it would take to properly reward a dragon as big as Tyrannis Pax.O_o I did forget that he carried Mortis in his arms though.

I think that T. Pax is the exception. The forelimbs on most bipeds (i.e Magma-calss dragons) look largely vestigial. Maybe they can only learn to use them with academy training.