Playing heel up on a bass drum?

Hi, whenever I play the bass drum for more than 10 minutes heel up, my leg really starts to hurt and it starts to have spasms so i can't play the correct beats. Has anybody got any tips? or had any experiences like this?

ive played heel up kick since i started getting into drumming. i have absolutely had those same problems before. there are a few things i can recommend...

1. your calves. work them, stretch them, build the muscle... all good. strong, resilient, fast calves will help with lots of drum/feet problems..
2. throne. i noticed that i needed to sit further back on my throne and sit up straight. it keeps my weight over my ass, instead of making my feet have to both balance and play. make sure your core, ass, and upper legs are in charge of balance. they are your strong muscles.
3. take something like an old flip flop and cut the heel off it. use some double sided tape and adhere it to your pedals heel plate (if its not a longboard). let your heel use this as a small boost to give you a heel-up resting spot.\

good luck