I think that Kytkattin has a point, and no one here really has any idea what her experience with dog nutrition is. She was giving an opinion on the product, which is what the original poster wanted, so why comment negatively.
Anyways, I wouldn't use this product. Flynn has no need for it and she is a high energy performance sports dog. She has no problem sprinting for hours on end, in whatever sport we are doing (disc/flyball/herding). I equate this with stage moms using pixi sticks to get their kids to perk up, and there's no way Flynn needs anything like this. After a long day, she still comes home ready to play fetch. I don't think she's ever really been tired. haha.
I'm sure some people use it, and they think it might give their dog an edge or something. I personally think it's a silly thing, and that dogs don't need it. Dogs can always go longer and harder than we humans think they can. I'm pretty sure it's just another way of the company making money. Also, I think far too many people would abuse this product not knowing what it's actually meant for. Like, oh I take my dog on a 30 minute walk, it must need ENERGY! I can't say how many people I've come across thinking their dog is a performance athlete, when all they do is walk with it.