I can't see any reason it wouldn't be OK. But a couple of things look slightly eccentric (not wrong, just strange choices).

Not sure what is the reason for splitting the workout data into three relations, as they share a primary key and if merged they would still (as far as I can see) be in 5NF.

Also not sure why there are three excercise type attributes in workoutmethod, rather than just one attribute that can take three values.