8 Retract your shoulder blades
Often, you don’t think much about what your shoulder blades are doing when training chest. You simply lower the bar to your chest and press it back up.
But it’s a bit of an understatement to say you’re simply lowering your arms behind the plane of your torso when going into the stretch phase. Rather, you’re retracting your shoulder blades as you complete the negative rep, swelling your chest out like a barrel. This may overexaggerate the curve in your thoracic spine, but remember, you’re stabilized on a bench when doing pressing movements.
This superior stretch enables you to better generate force through your pecs while stabilizing and protecting your shoulders.