It never fails to make me laugh when I see 136 pound guys in the gym training their rear delts. Does anyone know how ridiculous this? If you have been training for a number of years and have gained at least 40-50lbs of muscle and added at least 200+ lbs to your deadlift then you can start to think about to add in some rear delt training on occasion. Maybe not do it, but think about it.
Here is the real secret rear delt/ rhomboid/ upper back exercise that will pack more meat on those muscles than any other...
The deadlift.
If you start with a 225 pound deadlift today and increase that over the next few years to a 500 pound deadlift I can guarantee you that your rear delts, rhomboids, lower and upper traps will be enormous... or at least far bigger than they are right now.
Do you really think a bent over lateral raise with 20lb dumbbells is going to do more than a 500 pound deadlift? Not a shot in hell.
So until you have met the qualifications I listed above (or are injured), I suggest that you ditch the bent over laterals, the y-raises, the scarecrows, the band pull aparts and all that other stuff and stick with heavy deads for a few years. Once you add a couple hundred pounds to that exercise you can add in the above exercises if you still want to. But not before then.
JF
