Ok well I know people that can shrug 500lbs, a shrug does isolate the traps, so it is a true test of strenght for them, they are a very stong muscle.
I agree 100%
The same guy can upright row 160lbs and larteral raise 35`s, you think his traps fail while doing upright rows this very stong muscle that when isolated can shrug 500lbs when he cant do another rep on the upright rows? or is it his much weaker bicpes or delts that fail as when isolated stand like a fagot next to his traps in strenght terms.
The guy can also deallift over 500lbs, now isnt that much closer to the traps actuall isolated strenght, and row over 300lbs same again.
I do not doubt you can feel the traps work from upright rows, if i do 20lb leg extension and if i really concentrated i could feel my quad working too, shit i can do that with no weight ! does that mean its doing much.
But hey the the traps are near the delts arnt they "man thought they were same thing wrote it down on stone people follow it long time"
You should just say no to drugs 