First off I want to say sorry if someone already posted this (which I'm almost cetain they have, but I didn't want to scan through 23+ pages of post).

I have been playing for about 18 months, I like to play metal and I'm now trying to develop faster downpicking. I found an exercise on youtube which I've had recommended to me by numerous different people. Using a metronome, I start at a comfortable pace (70-75 BMP), then I downpick 16th note power chords - starting at open E up to the 12th fret E then back down. After every completion of the exercise I am to increase the tempo by 1 BPM - the exercise is completed after ten sets, i.e.:

Mon: 70 - 80
Tue: 71 - 81
Wed: 72 -82

So on & so forth.

I pay very close attention to make sure to use my wrist and not my arm, but any time I get up to around 90 BPM, my bicep starts to cramp up & burn. I also make an attempt to downpick Master of Puppets at a tempo that I play cleanly, but at 86 BPM - I'm not even at half-speed. I have been told that I should feel it in my forearm but I don't. I am in exceptional physical shape (though I completely understand that I am training different muscles to work in a different way) & I don't want to hurt myself.

Any tips?

Also if someone knows some control tips for play gallops and downpicking at high speeds (Disposable Heroes to be precise), those would also be greatly appreciated...

Thanks to all.
Jackson JS30RR
Ibanez RG170DX
Squier Stratocaster
Dunlop "Grommet" straps, strap locks & .88 Tortex Jazz picks
Behringer V-Tone GM108 (15 watt)
Boss ME-70
dont just step the speed up as soon as you feel you can go for a while at said tempo, get comfortable and play at that speed for a few days to a week, you will become even more relaxed and comfortable then. theeen you can step it up, but only a little
Play songs like no remorse and seek and destroy. seek and destroy isn't that quick, but if you downpick it all you'll strengthen up your wrist etc and get more comfortable with downpicking.
The part in seek and destroy just before the solo also helps (8th notes at around 208 I think)
And songs are a lot more fun to play than boring repetitive exercises
this wont be heaps helpful but another way to bring up speed is once you have an exercise down, in addition to slowly bringing up the tempo, sometimes it helps to play it faster than you actually can for a few minutes. Then go back to a slower tempo and you'll be more accustomed to speed and find it easier to play slower.

For myself, I found over analyzing my technique ruined the 'flow' or feel of it. After trying to perfect my technique I got nowhere and in the end I just went for it however it felt comfortable. And if its not comfortable, make it comfortable. Speed comes over time, don't obsess too much over it although there's nothing wrong with working on it. Also remember to keep up playing some songs, excercises aren't fun! good luck.
I know what video you're talking about (I actually know the guy)
And that exercise worked really well for me.
Just play along with songs religiously.
It's mainly about working on it every day.
If I'm on vacation or something I come back in pretty bad shape.
when you're out doing something practice it on a table or something.
(I'm doing it as i type)