It like getting any other pump in the gym. But this is in the lower erector spinae/lumbar region. I spend a lot of time carrying heavy lumber and hanging drywall so that gets it going at work.
In the gym deadlifts, squats, or any other exercise that requires heavy core stabilization gets it going too. It's not a shooting pain like nerve issues or a pulled muscle. It just gets extremely tight and is uncomfortable to remain standing. I usually have to sit down for a couple minutes and it will give me enough relief to continue the exercise....only to pump it up again LOL