Ok...now I've been playing over a year now so I probably should already know this but seeing as I'm self taught it's inevitable that I'm going to run into a few obstacles along the way, particularly with no teacher to lead my away from the wrong technique.

Warning, this isn't the shortest post in the world but bear with me...

Anyway, my problem centres around barre/power chords mainly and it is all down to the thumb position or, to be more precise, the angle in which the thumb is pressed against the back of the neck.

Now, I know how to play barre chords to a decent standard etc and things started off fine but in the last few months I've noticed that when playing them for a sustained amount of time (particularly with chord progressions around the 1st, 2nd and 3rd frets) not only my thumb came in for a lot of pain but the whole area between the thumb and index finger was giving me a lot of grief. I initially put this down to changing string gauge (from .009s to .010s) but after the pain not subsiding at all I figured that it was probably something to do with the way my thumb was pressed against the neck.

Last night I altered my thumbs position so the tip area of the thumb was pressed against the neck as opposed to the main 'base' (for want of a better term) of the thumb as I was doing before. And bingo, the pain went...but that's not really the end of the problem.

You see, I'm still confused as to what angle the thumb should be positioned at when it's pressed against the neck. I've started doing it at a similar angle to the one shown in the bottom picture but this position is hard to maintain when doing barre and power chords at the higher frets in which the angle in the first picture is more comfortable (which was also a similar angle to the one I was adopting whilst experiencing the pain) around higher frets.

So to sum up...which of the two angles shown below is deemed to be the correct one? Is there a correct one or is it just down to the player to use which ever angle they feel comfortable with? I don't want to really resume practicing barre chords too much without being sure on the 'correct' technique as it would just cause me problems in the future if I was using a flawed method for years on end. So I thought it best to consult people who have far more knowledge about the instrument than I do.

Apologies for the poor pictures, I'll try and shoot some in daylight if they aren't clear enough. Apologies also about my long winded description/explanation, it's not the easiest thing in the world to describe.

Picture One

Picture Two

Any help much appreciated, cheers.
On the second one your thumb is bent at a well weird angle. Try bending your wrist so the outside of your hand is more parallel to the fret board. This will take the stress of your thumb and help your fingers play more freely and let you move up and down the fretboard.
Also if you have big hands you can also wrap your hand around the neck with your thumb on the edge at the top of the fretboard.
hold a credit card, or some other sort of card between ur index finger and thumb, that's how you're thumb should be pressed against the back of the neck, that's how i was taught
It's natural to feel some tension when you're starting to use barre chords. You're using a lot of muscles that you've never used before (common in playing guitar).

It does take a lot of playing to overcome that initial pain, but before you know it, it becomes second nature. Just remember to stretch your fingers and thumbs before you play. That advice comes from John Petrucci's 'Rock Discipline' and I've noticed that it makes a big difference in your speed, accuracy and stamina.

It's good to work those muscles, but don't overdue it. You can really screw things up if you force it.

As far as the thumb position, I honestly haven't thought about it too much, but I lean toward the first position you are showing in your post.

Also, take it slow and work on making it sound good before you work on speed. You're using those muscles, but also 'teaching' them. If you do it right from the beginning, it will pay off big in the future.
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Quote by spunkeymonkey36
On the second one your thumb is bent at a well weird angle. Try bending your wrist so the outside of your hand is more parallel to the fret board. This will take the stress of your thumb and help your fingers play more freely and let you move up and down the fretboard.

Aye, my thumbs sort of bent in towards the neck in the second one...looks really awkward but it's comfortable enough around the lower to middle frets...just not particularly practical around higher frets.

I'll give a try to what you suggested anyway and see how that feels, cheers.
Oh, and just out of interest, does it matter which part of the thumb presses against the neck e.g. tip of the thumb? Or is it once again a case of whatever you're comfortable with?

One of the concerns was that I wasn't exactly new to barre chords when this pain started although I suppose it was new to playing them for a sustained period of a couple of minutes plus...although it could also be a case of slipping into bad habits.

I actually used to do that with my thumb, but I just trained myself not to.
I actually use my thumb in barre chords sometimes. Like, hang my thumb over and presse the top note with it. Not that I can't do it the right way, it just depends on what I played previously. Sometimes it's easier to shift to one than the other.

Bottom line, as longs as it works for you and you're comfortable, it shouldn't really matter.