Back training is pulls; shoulder training is mostly pushes. Simple enough, right? On the former, you focus on a variety of rows and pull-downs that engage a wide variety of real estate on your backside, including the lats, middle and lower traps, and rhomboids. Maybe you even do some deadlifts in there. On shoulder day, it's military presses, dumbbell presses, and isolation work like lateral raises.
But there's one muscle group that fits in a gray area between these two: your rear delts. These muscles on the back of your shoulders are highly engaged in multijoint back exercises where you bring your elbows back behind the plane of your body—in other words, rowing motions and that end-of-shoulder-day classic, the rear-delt fly.
But should rear delts be trained on shoulder day or back day? It may seem like splitting hairs, but there's more to take into consideration than you might imagine. Let's break it down.
Out of Site, Not out of Mind
It's likely not surprising that muscle stimulation on the rear delts isn't great on overhead shoulder presses. Those primarily focus on the middle and front delts, as well as triceps. After a few hard sets, your body will definitely let you know this is the case. But the research backs it up as well.
An unpublished EMG analysis from 2014 found that rear-delt activation was considerably less on the overhead dumbbell press than it is on the incline dumbbell row. This suggests to me that other kinds of rows also effectively engage the rear-delt musculature.
So if overhead presses don't really hit the rear delts, but rows do, why don't bodybuilders consider training their rear delts as part of their back workouts rather than shoulders? In fact, many do. But before you make your decision, here are some further points to consider.
You're probably double-dipping: If you choose to do rear-delt isolation exercises like bent-over lateral raises or reverse pec-deck flyes with you shoulder workout to ensure it covers all three delt heads, don't forget you'll get further rear-delt stimulation on your back days.
That means your rear delts are effectively being trained twice over the course of your split. This isn't necessarily a bad thing! On the contrary, it can be a great strategy to bring your rear delts up if they're lagging in comparison to the fronts and middles.
The rear delts still need rest: Typically, you don't want to work a muscle on consecutive days to allow for more optimal recovery. So, if you want to hit your rear delts hard, consider separating your back and shoulder workouts by at least 48 hours.
You could train back with shoulders: Yes, one potential solution to this dilemma is to hit both muscle groups in the same workout. If you do, start your training session with the larger muscle group—in this case, the back. Who knows; starting with back might actually be good for your shoulder health and pressing power!
Rear-delt isolation work still belongs at the end: If you train rear delts with back, add single-joint rear-delt moves after you're done all your multijoint back exercises, just like you would on shoulder day. The combo of multijoint rows and the rear-delt isolation moves will tax them quite effectively.