I wore a back brace occasionally when I was working at Lowe's and I was constantly lifting heavy stuff. 60 and 80 lb bags of concrete, 6x6s, sheets of drywall and plywood, concrete block, bags of mulch, etc. At my new job I don't have to lift nearly as much as I was lifting before, I can lift most everything with the forklift so I don't bother with it.Copper is antibacterial. As far as any benefit medically I doubt you'd see any benefit. These are meant to bind you and keep the muscles from taking a huge strain which they do. If they are restricting your motion then they are supportive. If they don't help then don't use it.
As I said I only use one for situations where I am gonna be lifting and twisting in a way that I normally don't. I take it off right after the lifting is done. Otherwise the muscles begin to rely on the belt instead of staying strong.