[1.III.5.1] Scales: Thumb Under, Thumb Over
Scales and arpeggios are the most basic piano passages; yet the most important method for playing them is often not taught at all! Arpeggios are simply expanded scales and can therefore be treated similarly to scales; thus we shall first discuss scales and then note how similar rules apply to arpeggios. There is one fundamental difference on how you must play the arpeggio (a flexible wrist) compared to the scale; once you learn that difference, arpeggios will become much easier, even for small hands.
There are two ways to play the scale. The first is the well-known "thumb under" method (TU) and the second is the "thumb over" method (TO). In the TU method, the thumb is brought under the hand in order to pass the 3rd or 4th finger for playing the scale. This TU operation is facilitated by two unique structures of the thumb; it is shorter than the other fingers and is located below the palm. In the TO method, the thumb is treated like the other 4 fingers, thus greatly simplifying the motion. Both methods are required to play the scale but each is needed under different circumstances; the TO method is needed for fast, technically difficult passages and the TU method is useful for slow, legato passages, or when some notes need to be held while others are being played.
Historically, many piano teachers were totally unaware of the TO method. This presented few difficulties as long as the students did not progress to advanced levels. In fact, with sufficient effort and work, it is possible to play fairly difficult passages using the TU method and there are accomplished pianists who think that TU is the only method they need. In reality, for sufficiently fast passages, they have subconsciously learned (through very hard work) to modify the TU method in such a way that it approaches the TO method. This modification is necessary because for such rapid scales, it is physically impossible to play them using the TU method. Therefore, it is important for the student to start learning the TO method as soon as they are past the novice stage, before the TU habit becomes ingrained into passages that should be played TO.
Many students use the method of playing slowly initially and then ramping up the speed. They do fine using TU at slow speed and consequently acquire the TU habit and find out, when they get up to speed, that they need to change to the TO method. This change can be a very difficult, frustrating, and time consuming task, not only for scales, but also for any fast run -- another reason why the ramping up method is not recommended in this book. The TU motion is one of the most common causes of speed walls and flubs. Thus once the TO method is learned, it should always be used to play runs except when the TU method gives better results.
The main piano playing muscles for the thumb are in the forearm, just as for the other 4 fingers. However, the thumb has other muscles in the hand that are used to move the thumb sideways in the TU method. The involvement of these extra muscles for the TU motion makes it a more complex operation, thus slowing down the maximum speed attainable. The extra complication also causes mistakes. Teachers who teach TO claim that for those who use TU exclusively, 90% of their flubs originate with the TU motion.
You can demonstrate the disadvantage of the TU method by observing the loss of thumb mobility in its tucked-in position. First, stretch your fingers out so that all the fingers are in the same plane. You will find that all the fingers, including the thumb, have mobility up and down (the motion needed to play the piano). Now, wiggle the thumb up and down rapidly -- you will see that the thumb can move 3 or 4 cm vertically with ease (without rotating the forearm), quite rapidly. Then, while still wiggling at the same rapid frequency, gradually pull the thumb under the hand -- you will see that as it goes under, it loses vertical mobility until it becomes immobile, almost paralyzed, when it is under the middle finger.
Now stop the wiggling and thrust the thumb down (without moving the wrist) -- it moves down! This is because you are now using a different set of muscles. Then, using these new muscles, try to move the thumb up and down as fast as you can -- you should find that these new muscles are much clumsier and the up and down motion is slower than the wiggle rate of the thumb when it was stretched out. Therefore, in order to be able to move the thumb in its tucked position, you not only need to use a new set of muscles but, in addition, these muscles are slower. It is the introduction of these clumsy muscles that creates mistakes and slows down the play in the TU method. The objective of the TO method is to eliminate these problems. The obvious question is, "what price do you pay for it?"
Scales and arpeggios are some of the most abused exercises in piano pedagogy -- novice students are taught only the TU method, leaving them unable to acquire proper techniques for runs and arpeggios. Not only that but, as the scale is speeded up, stress begins to mysteriously build up. Worse still, the student builds up a large repertoire with wrong habits that will need to be laboriously corrected. The TO method is easier to learn than the TU method because it does not require the sideways contortions of the thumb, hand, arm, and elbow. The TO method should be taught as soon as faster scales are needed, within the first two years of lessons. Beginners should be taught TU first because it is needed for slow passages and takes longer to learn. For talented students, the TO method must be taught within months of their first lessons, or as soon as they master TU.
Because there are two ways to play the scale, there are two schools of teaching on how to play it. The TU school (Czerny, Leschetizky) claims that TU is the only way that legato scales can be played and that, with sufficient practice, TU can play scales at any speed. The TO school (Whitesides, Sandor) has gradually taken over and the more insistent adherents forbid the use of TU, under any circumstances. See the Reference section for more discussions on TU vs TO teaching. Both extreme schools are wrong because you need both skills.
The TO teachers claim that the TU method is the cause of a majority of flubs and that if you practiced each method the same amount of time, you will be playing far superior scales with the TO method. They are understandably angered by the fact that advanced students passed to them by private teachers often do not know the TO method and it takes six months or more just to correct hours of repertoire that they had learned the wrong way. One disadvantage of learning both TU and TO is that when sight reading, the thumb might become confused and not know which way to go. This confusion is one reason why some teachers in the TO school actually forbid the use of TU. I recommend that you standardize to the TO method and use the TU as an exception to the rule. Note that Chopin taught both methods (Eigeldinger, P. 37).
Although the TO method was rediscovered by Whitesides, etc., the earliest account of its use dates back to at least Franz Liszt (Fay). Liszt is known to have stopped performing and returned to developing his technique for over a year when he was about 20 years old. He was dissatisfied with his technique (especially when playing scales) when compared to the magical performances of Paganini on the violin, and experimented with improving his technique. At the end of this period, he emerged satisfied with his new skills but could not teach others exactly what he had done to improve -- he could only demonstrate on the piano (this was true of most of Liszt's "teachings"). However, Amy Fay noticed that he now played the scale differently; instead of TU, Liszt was "rolling the hand over the passed finger" so that the thumb fell on the next key. It apparently took Fay many months to imitate this method but, according to her, "it completely changed my way of playing" and she claimed that it resulted in a marked improvement in her technique generally, not only for playing scales.