Pressure points in your back and shoulders can quickly become painful knots and if they are not properly dealt with. They can also prevent muscles from fully engaging when lifting. If you try doing big lifts with only part of the target muscle group firing, you can find yourself on the PUP list sooner than later.
The best tool I have found to combat muscle knots in my back and shoulders are lacrosse balls. I prefer lacrosse balls over foam massage balls because of their firmness. Lacrosse balls also cost a fraction of the price of foam massage balls.
One nice thing about foam balls is that they come in a variety of sizes. I prefer the option that is about the size of a grapefruit. I find it really helpful for my lower back and sciatica area. The larger size is also less painful on the hammies and quads because it doesn't feel like you're being stabbed with an elbow or something.
I tried using the foam ball that was about the same size as a lacrosse ball on my shoulders for a few months. After working the foam ball around for a while between my back and the wall, I realized I was pushing kinda hard. Not only did I turn a sphere into something that resembled an egg, but I also put dents in the drywall around my house, pictured here:
These are not small dents either. Each patch of dents is about 10 x 12 inches. Yes, I do realize there are two separate sets of dents on two separate walls. My shoulder pain was so bad I truly didn't care at the time. When I noticed I had screwed one wall I simply thought, "it's my shoulder or the wall" and I moved to another wall and went to town.
That's the main problem I have with foam roller balls. They're soft. Too soft. If you have serious muscle knots and you use a foam ball to try to work them out, you're going to press pretty hard. The directions that come with the foam ball kit suggest putting a ball on the ground and lying on it. That was too much for me. I feel like I'd break a rib somehow.
Lacrosse balls are pretty hard. Not as hard as a baseball but not as soft as a tennis ball. They're the Goldilocks of athletic equipment. But since they are kinda hard, you don't lean on them with nearly as much force as you might with a foam ball. That means they don't put giant dents in your walls either and they don’t lose their shape. You don't push as hard, you get better relief and you spend less money in the process. Kind of a no-brainer.