Train your rear delts

I feel there has been a recent push on the internet to expose rear delt training. Its tough, because its not sexy.

Training your rear delts will eventually give you the 3d look their promotional material pushes, but their main value is they act as a key to larger shoulders (as opposed to a main driver).

When you press (any angle), all 3 heads are going to take a part in the action. There's just no other way. If you imagine your mid and rear delts are sipping on long islands yelling MUSH MUSH while your front delts cry the weight up, you are sick. Fuck you. Sick. That's not entirely the case though. Your anterior (front) delts are the powerhouses of pressing while your mid and rear delts primarily stabilize the weight. They are getting their hands dirty, but the rest of the contributing stabilizers and movers - traps, upper back, glutes, quads, abs, anterior delts - are way stronger and firmly take the pressing reigns.

This tells us a few things:
1. Training rear delts is important in the same way that training your back is important. A one sided muscle balance (anterior versus posterior) is eventually going to cause pain and/or injury.

A similar comparison would be shin splints for runners. One part of the lower leg is overdeveloped, so intense pain is felt on the shin due to the muscle pulling tight again its antagonist (and no muscle on the other end to pull back).

2. Training your rear delts needs to be felt
Light weights apply here.

Because rear delts play stabilizers, their incidence of actually contracting is very low. Use low weights to actively engage your rear delts in a contraction to build them. They are a small ass muscle, you do not need a lot of weight to make a difference here.

Using too much weight will activate the same response as heavy pressing. Your rear delts will stabilize the movement, but your traps and upper back will get greedy and move the weight. Congrats, you just turned a great rear delt movement into a shitty trap exercise.

There are cheating and partial rear delt movements that should be thrown in the mix as well, but the majority of your rear delt work should be light and leave you with a distinct muscle pump.