Isometric exercises are an old school exercise to increase strength. isometric contractions are contractions were the muscle can’t shorten because there is a resistance that can’t be overcome.
The drill is pretty simple. find a tree and stand about even with the tree with the front foot. now you approach the tree slowly with the Bat like a slow motion swing and then you push as hard as you can against the tree for 3-4 seconds and you repeat that about 10 times.
Ideally you use a slightly incline tree so that you can push slightly upward like in a swing.
However the word push is a little misleading. You do not want to use the arms but use the turn of the body.
-pull the front shoulder back and up
-hands stay on on the plate side of the body (right for righty)
-hips are extended
-body slightly leaning back to no back arch, keep arch tight)
That drill is for good posture at contact which can lead to better launch angles. losing that posture often leads to lower launch angles.
It also isometrically trains the rotational muscles of the body and also trains forearm strength. Overall it is a good drill that trains all the muscles that fire in a swing and it also reinforces a good contact position.
Physically you are not pushing through contact in a baseball swing but it still is a good drill for better posture and strength.