Does the Arnold bag have internal support? I need a bag that is sturdy and will stand open.

I am not sure if by support you mean a rigidness to stay open or to stand up. If you mean to stay open, not really. However, if you look at the inside picture of the bag you will see that it's a pretty open gym bag. Easy access to all your gym needs! If you mean is the bottom a hard, solid bottom then the answer is no. It's an all around soft sided bag. That is so you can cram it into those narrow gym lockers!