My mental model is this: Old cells have DNA mutations. Short telomeres tell the cells that they are old and should take it slow and be careful not to accumulate more mutations (senescence).
Any simple treatment like oxygen therapy, will be unable to fix DNA damage. It has mutated already and thats that. What it might do is to "lie" to the cell. "You are perfectly healthy", when it actually isn't. This has benefits, such as more rapid healing of injuries, and it has drawbacks such as cancer.
I think it's much more likely that old cells just have an accumulation of crud, like a house that is old and doesn't get cleaned enough.
We don't really have a good definition of "aging" because we don't really know what causes the body to give out after a certain amount of time has passed.
Any simple treatment like oxygen therapy, will be unable to fix DNA damage. It has mutated already and thats that. What it might do is to "lie" to the cell. "You are perfectly healthy", when it actually isn't. This has benefits, such as more rapid healing of injuries, and it has drawbacks such as cancer.