Hi, fellow guitarists!

I had a lot of difficulty with bar chords, but I'm able to do them after a lot of practice. But there's one problem: my thumb starts to severely cramp up after I hold a bar chord for about half a minute. It's killing me. I used to practice an hour a day and I used to ignore the pain. But now I want to get rid of it really badly, so I can play songs with bar chords and actually enjoy doing it. I know a classical guitarist that advised me to practice less and build up the amount gradually. Well, I played for fifteen minutes a day for the last two weeks and it's still not helping! Scales, open chords, bends, ... no problem, but those bar chords just kill my thumb!

Please, if anybody has any ideas on how to fix my thumb strain, I would be eternally gratefully.

Hi Joshua, how are you doing!
You need to have a lot of patience with this, I recommend you to read the FnF post
Here's a tip from my last post on that thread:
Quote by zyryab
make a bow with the finger so you don't press the unnecesary strings played by the other left non-barre fingers (in F case would be 3,4&5th), and the strength goes to the tip of the index and to the base knuckle, which you should try to pull back.
Don't do this for a very long time and make stretching excercises so you don't get hurt.
Interrupting your playing because of this can be frustrating!

Take care!

Hope it helps!
Thanks for your input Mariano. The problem is that I actually already use that technique. I have no problem with playing bar chords, I can play them reasonably. It's just my thumb. I've searched a lot on the Internet and I believe that it is necessary to use my arm and shoulder muscles. But I haven't got a clue on how to do that exactly. I've tried searching on Youtube, but Youtube thinks that I want to learn how to do a Pilates workout properly.

The position of my thumb is in the middle of the neck, pointing towards the headstock ( hitchhiker position )

If you've got some more tips I'd really appreciate it.