By Laurel Thomsen
The thumb plays a key supporting role for the fingers of the left hand on violin and viola, but the left-hand thumb can be a help or a hindrance. When kept in check, it orients our left hand within a position while providing a counter-pressure for the finger action upon the strings. When it goes overboard it can cripple the left hand, leading to issues with finger accuracy and velocity, vibrato, shifting, and playing health. Since the thumb does not play any notes, it needs to do only what will support the other four fingers and their actions.
Here are 4 ways to free your left thumb.
1. Get comfortable
Without your instrument, try raising and lowering your left hand into playing position several times, keeping your fingers and hand relaxed.
With your instrument now, bring your left hand up into playing position. Is there any tendency to grip the neck? If so, you may need to find a more secure instrument hold. A fear of dropping your instrument will make relaxing your hand very challenging.
Check and recheck your posture and instrument hold. Each time you bring your hand up to the neck release any tension or gripping. There is nothing to fear!
2. Add counter-pressure
Since the finger action on the strings is a downward pressure, the thumb needs to provide an upward pressure.
In playing position, notice that your thumb pad gently adheres to the neck of the instrument. It’s really not going anywhere you don’t tell it to go. Try dropping the second finger onto a string and let your thumb press upward rather than inward (Fig. 1).
A relaxed thumb will do this naturally, providing the counter-pressure needed for the fingers to depress the strings without the gripping that makes fast fingers, excellent intonation, and smooth shifting nearly
3. Watch the positioning
Place all four fingers in any finger pattern on the A string in first position. Slide the thumb into a place where all four fingers feel equally strong and comfortable. Now try another pattern, and another, adjusting your thumb as necessary each time.
You are discovering the thumb position that supports each finger placement, likely somewhere between the first and second fingers of each pattern (Fig. 2). This is home base. However, there is no reason why you can’t make minor thumb movements while playing to facilitate the placement of your other fingers, especially if your fingers are relatively short.
To practice, as you prepare to place a fourth finger, move your thumb in the direction of the fourth finger for an easier reach. When stretching back for a low first finger, move your thumb slightly toward the scroll. Focus on strong, secure fingers and thumb adjustments that help. Return to home base after each adjustment.
4. Check your vibrato
A relaxed thumb will aid vibrato while a tense one will stifle it. In a good wrist vibrato the wrist will cause the thumb to pivot slightly, in opposition to the rocking finger. As your finger rocks back toward the scroll the thumb will rock toward you and vice versa (Fig. 3). For arm vibrato the thumb will generally rock in the same direction as the finger (Fig. 4). Practice vibrato slowly at first as you learn to let your thumb move. Thumb movement will especially help those with a fast and narrow vibrato to slow and broaden it.