One of my students just flashed me a thumbs-up. Not because they like me (even though they do, of course, because hey, why wouldn’t they?), but in homage to one the recurring topics in my beginner lessons – the never ending battle of the thumb.
Your Best Friend
When your hand is properly positioned, your thumb does a lot of the work for your left hand. First, it gives your fingers something to press against. The force that holds down your string is a combination of pressure from your finger and thumb – think of them like a vice grip, with the guitar neck and strings in between. This helps you keep your fingers properly arched and allows you to more clearly voice the notes and chords you are playing.
Second, your thumb provides an anchor point for your whole left hand. Even when playing your first notes and chords, you will find that having your thumb properly centered and aligned will help you maintain a “home base” for your hand, especially as you begin playing more with higher fret positions, and especially more especially when you start messing around with arpeggios.
Your Worst Enemy
The problem is, the proper hand position also goes against the way we’ve used our hands for most of our lives. When we pick something up, we grab it, using not only our thumb and fingertips, but our entire hand. Handshake? Grab. Doorknob? Grab. Baseball bat? Grab. Generally speaking, we depend on that stable grip to help perform whatever task we are undertaking.
Guitar, however, is completely different.
To illustrate this, take your left hand completely away from your guitar. In fact, you know what? Raise it up over your head. Now, with your right hand, strum your guitar a little bit. Now, you are not voicing any chords, so unless you are using an open tuning, it will sound jangly. No matter – the important thing to notice is the neck of the guitar. Unless you are dancing a jig and/or having a seizure, you should notice that the guitar neck isn’t swinging wildly, it isn’t twisting and turning, and the headstock isn’t poking your eye out… in fact, it all stays in place just fine without your left hand.
So, you don’t need to worry about grabbing the guitar neck. Brilliant! This means that you can focus on your thumb, and give your fingers a good solid floor upon which to dance.
Doing it “Right”
When your thumb is properly positioned, it will be across the back of the guitar neck, perpendicular to the direction of the strings. Think of this as your anchor point, your main connection to the neck of the guitar. Now, let’s voice a chord. Pick a familiar chord (it doesn’t matter which one, but choose something nice and easy) and reach your fingers around until they are pressed against the fretboard. Your fingertips should be at a 90 degree angle to the fretboard. This will place your wrist be slightly below and away from the guitar (as always, the standard rule of any exercise/stretch/experiment/whatever with your hands and fingers applies – be careful, be gentle, and if you are in pain, stop immediately).
This is exactly where it feels weird to a lot of people, mostly due to our innate grabbiness that I mentioned earlier. Your wrist will probably yearn to press against something, and your thumb will almost certainly display a grim determination to creep over the top of the guitar neck. Fight it, my friend, you must fight it! With practice, you will eventually be able assert your will over your thumb and force it to do your bidding; however, the tendency towards guitar neck death grip is hard to shake, and for many folks out there, the battle is a lifelong one.
Doing it “Wrong”
I know, I know. You see people hanging their thumb over the guitar neck all the time, and a lot of musicians even use their thumb to voice notes. Take “Pinball Wizard” by The Who – that guitar part uses the thumb for darn near every single chord! In terms of classical technique, Pete Townshend is doing it “wrong”, but listening to the song makes it clear that he plays that guitar part oh-so right. And really, at the end of the day, if something feels and sounds right, then it IS right, dadgummit.
That said, for the majority of guitar players out there, proper positioning of the thumb plays an incredibly important role in the sound of your music, even though it will fight you every step of the way 