Just recently I have been starting to get upper forearm pains when I play guitar in my right arm[picking hand].
Never happened before but now it is.
It happens mostly when I shred but sometimes it just happens out of the blue.
I don't know what it is.
I play with right posture.
The only thing I can think of is the tension I am putting on my body, but I try to stay loose when I play, and I believe I do.
And help, tips?
Stop playing for now. You might need to change your picking technique.

Read through the sticky to ensure that you practice with proper technique. If you don't, I'll make it EXPLICITLY clear, anyways...

The picking technique involves the entire arm...

1.) The picking motion comes from the wrist as much as humanly possible. The degree of motion can and will vary from player to player.

2.) The string changing motion (for example, from the G to B string) is a subtle movement that comes from the elbow and is in no way, shape, or form associated with any tension. <--- Yes, I basically ripped that line off from Martin Goulding, that amazing Guitar Techniques magazine contributor.

If someone uses an extreme, such as "USE ONLY YOUR WRIST!" or "ONLY YOUR ARM!"...they are an idiot and you should hastily dismiss them.

Good luck!

EDIT: I can't believe I almost forgot Freepower's goldmine of information on picking, which can be seen here...http://www.youtube.com/user/FreepowerUG#p/a/u/1/VkeyHyIgqvY

I tend to use mostly translatory picking with a tiny, tiny bit of oscillatory movement...every picking style should involve healthy, tension-free usage of the elbow to keep the same picking angle relative to the string you're on. FP talks about that, too, in the video.
Quote by Junior#1
Gilbert mutes with both hands. Palm muting and left hand muting. As for anchoring, he doesn't. He doesn't need to. After all, he's the creator of life, the universe, and everything.
Last edited by plainsight at Nov 4, 2009,
Youre probably picking wrong as has been suggested above and that's whats putting excess strain on your forearm. Slow it down and do it correctly or you'll injure yourself and have to stop playing.
If you're playing with the right posture, perhaps you have a cold - it can cause muscle pains. Or you're getting faster and better and new muscles need to develop
Last edited by sergiu at Nov 4, 2009,
Have you started to play more "shred" or fast picking than before?

Muscle aches can be caused my tension, but they can also happen if you're not drinking enough water.

Maybe that is what's changed?
If you're using certain techniques more than you have been previously, you're using muscles that aren't used to being used so much. It's natural to have some soreness, try to rest a bit and examine your technique to make sure you aren't putting too much strain on yourself by playing the wrong way.
Andy Fox
Hard rock guitarist
I play a Jackson DK-2 and an Ibanez RG through a Peavey 6505+ stack