Exercises involving elbow pressure into a cushion with deep breathing can activate latissimus dorsi and external rotators.

“no more than two pounds of pressure i'm going to drive this elbow into the cushion and you should feel all this kick off see if i press here these muscles are really strong and tight and now i don't know what you're doing is breathing and trying to fill your whole rib cage in the presence of that tension so now just relax it and rock your body upward give a little micro break you can relax this pressure too good feeling right and then drop down again and press the elbow down good upright that fine breathing here filling your entire rib cage and while that fills here this shouldn't change”