I have been practicing more and more lately and find that after a few days in a row of more than 90 minutes of practice my hands and arms start cramping up and I can’t play well no matter how slow I go. But I have the time, I enjoy playing, and doing a lot of practicing is really making me better so I want to stay at it. I already break up my practice sessions into a few short sessions, but would it help to arrange things so that I practice emphasize fast rhythm playing one day and lead the next? Or should I just cut back and start working myself up to more practicing?
If its just fatigue, then we are okay, if you are doing damage to your arms/wrists/hands then id tone it down alot for now. Do you notice that your starting to build up stamina? or is it just like an hour of playing then a solid wall of tired limbs? But ya if you want to get alot of practice done, i wouldn't wear yourself out in the beginning, work on slow stuff like hard licks or scales or whatever, then at the end when youve "paced" yourself, work on those fast rhythms.
you need to do a proper warm up. it`s like a runner running a marathon, if he doesn`t warm up, his muscles he`s going suffer cramps and injuries. use the searchbar and youtube for warm up excersises just remember you got to stretch your upper body, arms and wrists before picking up the guitar, a good warm up will take 30-45 minutes
I know... "I used to play my guitar till my fingers used to bleed..." Common work ethic, especially with you young guys.
But you can be causing yourself long-term damage. Back off a bit. Take a couple days rest, then as ibanezgod says a nice warmup before your practice session and maybe cut down on the total time.
Make sure your position is good. If you're in the habit of playing with that sexy "low slung" position you're putting a lot of extra strain on those tendons.