#1
There's this chromatic legato exercise (which I'm sure you may have all heard of) that goes 1-2-3-4 going up (hammering-on) on all the strings, then 5-4-3-2 (pull-offs) and so on up the fretboard, up to 10th position, and back down again. However, I find that when I go back down to 2nd/1st position, there's this awkward ache in my hand. The pain is in the bit by my thumb. I position my thumb in the middle of the neck, below where my middle finger is placed. Does anyone know why I'm experiencing this pain in my hand and how I can avoid it?
Curses...i have nothing of interest to write in this here place.
#2
Quote by GunsN'tallica
There's this chromatic legato exercise (which I'm sure you may have all heard of) that goes 1-2-3-4 going up (hammering-on) on all the strings, then 5-4-3-2 (pull-offs) and so on up the fretboard, up to 10th position, and back down again. However, I find that when I go back down to 2nd/1st position, there's this awkward ache in my hand. The pain is in the bit by my thumb. I position my thumb in the middle of the neck, below where my middle finger is placed. Does anyone know why I'm experiencing this pain in my hand and how I can avoid it?


The simplest source of the problem would be that you're pressing down too hard with your thumb. That's the problem with the classical hand position - you can have more fretting accuracy but you need to be more "in tune" with the pressure that your thumb has on the neck.

I'll just say this, just in case you don't know it already: Your thumb is just supposed to be a guide for your fingers, not a gripping tool. If you ever have to lift the neck up, you should only have to do it with a minimal amount of force.
#3
I don't mean to criticize, but it may be a result of how you hold the guitar while playing.
When I started playing when I was young (as in around 1957 - geez I feel old!), I rotated the guitar so that I could directly see the finger board. I just didn't have the confidence to "find" the fret(s) without looking. So, to do that I had to rotate my wrist - a lot. That put a lot of strain on it, and for a number of months I had pain.

Then my teacher said to become better at just "knowing" where the frets are, use the position markers on the edge of the neck (if you have them), and reduce the sharpness of my wrist to forearm angle. In other words, I had to relearn how to hold the guitar to make the pain go away.

I am almost 60 now (hear me snoring?) and I can and do play every day for at least an hour. Stick with it. You will get better, and maybe even be great!

Try everything - music is a passion!