I have recently switched to playing heels up, but I am having problems with my leg getting tired. It is mainly a problem when playing constant quarter notes and my leg doesn't have time to rest. I have the springs on my pedal at mid tension, when I sit on my throne my leg is slightly angled down toward the bass drum, my beater angle is about 45 degrees, when I sit my knee is directly above my heel, and I rest my heel on the floor when I can between beats. Does anyone have an idea of what I might be doing wrong? My apologies if this has been discussed before.