Here is the context:
These are the most effective exercises for building muscle as identified by science.
Does as identified by science means the same as which was identified by science?
Per identified or according identified is not used. That's why they used as identified. They are trying to stress to the reader that it is something that has been identified by science. If you say "according to science" it more seems to infer that they are referring to commonly known laws of science, which they are not. You could also say "which was identified by science" to mean the same thing.
as identified by science ~= per science, or according to science, which science has identified.