Just finished Guitar Fundamentals 1 and started Guitar Fundamentals 2. Prior to signing up for GuitarTricks, I was self taught, and I'm amazed how much better my tone and chords sound just from learning proper technique over the past few weeks.

I now have a question on power chord shape technique. I've always played power chords by using my pinky finger as a bar across the 4th and 5th strings instead of using my ring finger on the 5th string and pinky on the 4th string. I've been trying to master the power chord groove using the proper shape technique, but my hands cramp up before I even finish the lesson, partially because I don't have very long fingers.

My hand keeps wanting to revert to the shape of using my pinky to bar the 4th and 5th strings. Is this improper technique that I should keep working to break the habit for, or is a pinky bar an acceptable alternative shape for making power chords?

I am also struggling a bit with proper thumb placement on power chords, although I would say this keeps emerging as a problem even on open chords. Thank you!