Position of Left Thumb in Cello Technique
Remember these Principles
Know your pivot joints
Know your active motions
Know your passive motions
Use anatomically neutral positions
Motion can loosen tension
Do not hinder passive motions
Use fluid rather than static technique
Divide up the work
Use large muscle groups
Tension and release
It may seem odd to have an entire article devoted to the position of the left thumb in cello technique. The reason for this is because "traditional" cello technique maintains that the left thumb should always stay across from the second finger and I disagree with that. This is another example of what I call "static technique". In other words, it prescribes a position for the thumb that is stationary. I prefer a "fluid" cello technique. Please see my article on technique fundamentals.
As teachers and cellists, we all know that the left thumb is prone to tension: it tends to squeeze. And a tight thumb results in a tight hand.
Tight Thumb = Tight Hand
Press the pad of your left thumb against the pad of your right index finger. This will cause the thumb muscle to contract. Now try moving your fingers quickly. Take your left thumb away from your right index finger, allowing the thumb muscle to relax, and move your left fingers quickly. Which has less tension in the hand? You probably notice that the less tense the thumb muscle is, the less tense the hand is also. So it is absolutely vital to maintain a loose thumb while playing.
Hold your left thumb across from your second finger. Now try to move your fingers quickly. Now hold your thumb across from your first finger. Try moving your fingers quickly. Which is easier? My guess is that you felt more ease of playing with your thumb by first finger.
Why is this? Most likely, the anatomically neutral position (for definition see this article) for your hand is when your thumb is across from your 1st finger, not your 2nd finger . When you deviate from this anatomically neutral position, it takes extra work (muscle tension). The extra tension in the thumb creates extra tension in the hand.
So remember the principle;
Use Anatomically Neutral Positions whenever Possible.
While positioning your left thumb across from your first finger, feel the thumb muscle.
While positioning your left thumb across from the second finger, feel the thumb muscle.
While positioning your left thumb across from the 3rd finger, feel the thumb muscle.
While positioning your left thumb across from the 4rd finger, feel the thumb muscle.
Which position causes the most tension in the thumb muscle? I am assuming you found that the most tense position is one where the thumb is across from the 4th finger. Which position is the loosest? Isn't it the one where the thumb is across from the 1st finger? The further you get away from the anatomically neutral position, the tighter the muscle.
So why does tradition tell us to keep our thumbs across from the 2nd finger? It comes from the premise that that we should avoid extra motion at all costs (i.e that would be inefficient). Therefore, it seeks for a position that works reasonably well for all the fingers so as to avoid any change in position in the thumb (extra motion). Traditional cello technique tends to favor a "static" technique as opposed to a "fluid" one.
So am I not also advocating a static technique by insisting that the 1st finger always be across from the first finger? Not at all. This leads me to the next section.
Use a Fluid not a Static Technique for the Left Thumb
Hold your thumb across from your second finger in 1st position and vibrato on 1st finger. Now, place your thumb across from your 1st finger and vibrato on your first finger in first position. Which allows for more freedom?
Now, place your thumb across from your 1st finger in first position and vibrato on 4th finger. Now, place your thumb across from your 2nd finger and vibrato on 4th finger. Which allows for more freedom?
Most of you probably felt that the 1st finger vibrato was freer when your thumb was across from your 1st finger and your 4th finger vibrato was more comfortable when your thumb was across from your 2nd finger.
So I advocate having a position where your thumb moves according to which finger you are vibrating. This way, we use the most anatomically natural position of the thumb when possible and deviate from it only when necessary.
What about Fast Playing?
Try Experiment II again. Come back when you are done.
OK, what did you find? Did your fingers tend to move faster when the thumb opposes the 1st finger? I have yet to find a person whose fingers moved faster with the thumb across from the 2nd finger. If you are an exception, I'd love to hear from! Because of this, in fast playing, I prefer to keep my thumb across from the 1st finger. For a related article read about hand rotation on the cello
Remember: Think critically, analyze your technique, and always experiment!