ha, no the pump has nothing to do with lactase. It refers to blood filling your muscles -- you probably get a pump in your forearms from climbing. Feels like someone stuck a bike pump in your arm and "pumped" you up.
Interesting. Yeah it's a different feeling I think for climbers. From what I've read it's lactic acid build up, like when I fully crimp it hits the forearms hard after a bit just not able to grip anymore
