How far are you supposed to push yourself when trying to build stamina?
I think I *might* be overdoing it, as I'm feeling a slight twinge of pain in my lower forearm (just where it meets my wrist) whenever I move it too quickly. I think this was probably caused by my current approach to building downpicking stamina, which consists of picking a tempo that I think I can handle and then playing a riff that uses a lot of downpicking at that speed for 4 minutes. If I start to feel my wrist ache, I push through until that 4 minutes is up, no matter what. No matter how much I have to tense up. As long as I get through that 4 minutes with it sounding coherent I count it as a win. Now that my wrist/forearm is hurting, I'm starting to think I may need to alter my approach. However, doing it any other way seems counterproductive to me because if I'm not pushing myself to near-failure, then I'm not pushing myself hard enough to improve, right?
How would you recomment I approach this? How did you do it?