[Muenchener]

My brachioradialis gets sore if I so much as look at a steep boulder problem. It's fine on routes. Stretching and massage seem to help, but is there anything else I should be doing / not doing? Simply wait for it to get stronger?

[slackline]

Avoid looking at steep boulder problems. 

[shark]

I get a bit confused with the bits starting with Brachi... but if it is the muscle under the bicep then try freezing water in a yoghurt pot then using it to press right into the source of the pain for a few minutes each night before bedtime. I had it a couple of years ago and tried a few things but it just persisted till I did this and then it went away and hasn't come back.   

[Muenchener]

I get a bit confused with the bits starting with Brachi... but if it is the muscle under the bicep 

That's not the one I meant (although it might be the one whose name i used.) The one I meant is the elbow flexor in the forearm and (checks anatomy book ...) it is indeed called the brachioradialis.

So clearly I need to spend more time on straight-arm, eyes closed technique exercises.

[shark]

Ah - sorry. Have you experimented with the stretch illustrated on the second page of this article?

[douglas]

Perhaps it's weak and needs strengthening. You may be able to tweak this exercise to hit the BR

http://www.ukclimbing.com/articles/page.php?id=3614

[Fultonius]

It could be your shoulders!

Is it a very sharp, pin point pain or more of a general malaise?

[Muenchener]

It's a general soreness. Not pumped, more of a nearly but not quite pulled/strained soreness/ache.

Have you experimented with the stretch illustrated on the second page of this article?

Yes, I learned that stretch in a bouldering technique course that I did in May, and it does help to relieve the soreness. But I'm wondering if I might need to find a way to specifically strengthen the muscle. Not sure how, though, because apart from bouldering nothing else I've ever done seems to bother it. Weighted pullups, campusing etc. - no pain.