What they are trying to say when using the words "старший" and "младший" is:it has always been the nationals of elder age.
Juniors - senior group/division/segment
Juniors - junior group/division/segment
Novice - senior group/division/segment
Novice - junior group/division/segment
When translating into english, one should add "group or division or segment", because "старший" and "младший" is actually an age division with in a competition category.