What a dick
Never had them. I honestly don’t get what “pumped” lower back feels like. You say pumped. Like tight and hurting then goes away?
I’d say it’s a tight, dull pain across your back somewhat reminiscent of the feeling in your quads after doing a burnout set on leg extensions. Immediate relief begins to come as soon as you lay down and relax the back muscles. Then get up do another set and it all starts over again.