(For legal reasons, I should briefly stress that all exercises are undertaken at your own risk. Please note that while the videos provide a valuable illustration aid, it's the thinking that runs behind the movements that matters the most. It's very important to follow the instructions of each exercise- rather than only the videos. If you do so with due care and pay attention to the feedback from your perception, there should be nothing to fear. However, take special care if you have prior injuries or medical issues. Above all, anyone should stop immediately in the unlikely event of discomfort or pain. None of the movements involved should feel anything less than comfortable and even pleasurable to execute. )
Anyway, let's go straight to the piano. Try to make a massively sonorous melody line, using only the thumb of the right hand (plus pedal for legato) for long, broad notes. While you can use whatever piece you like, something like the opening melody from Chopin's op. 25 no. 12 would be extremely suitable. However, I have no desire to exclude anyone. Do a slow thumb-only version of "Mary Had a Little Lamb" if you wish- as this exercise is suitable for all levels!. The performance below gives an excellent idea of the type of sound you're looking to make (with a bell-like quality to the line)- but forget the flurries of notes! Only play a melody line (plus bass, if desired)!
Don't think too much about the movements the first time around- think of the intended sound and just do it! Once you're finished, think a little about how you found yourself moving when striving for that type of sound. Maybe even repeat it and pay more conscious attention this time. Also, how happy were you with the musical sounds you produced? It might be worth recording yourself to see how it sounds upon playback. If you're honest with yourself, did you manage to come anywhere near producing the type of "golden age" sound that (the surprisingly little-known) David Smith produces? Maybe you succeeded in creating a pleasant enough musical line- but only by sticking within a very "polite" and gentle dynamic range? Or maybe you knocked seven shades of shinola out of the piano, but failed to achieve the seamless quality of tone required for a genuinely vocal melodic line? Without thinking too much about anything but the sound and the musical goals, spend a little time trying to improve upon the results and see how you fare.
We'll come back to that shortly. However, firstly, rest your right hand very lightly on a solid table top, palm down. Start to exert a moderate pressure against the table through your thumb. Now imagine the table is a piano key and do the same once again. Was the action the same or different?
Okay, now let's look at what you actually did there. Firstly, I'd be willing to bet that at least 90% of people will have performed every one of these actions (at both piano and table) by pressing their arm through either a stiffly braced thumb, or a floppy and inactive one that collapses. Before I go any further, if you hold the typical belief that big sounds should come from actions of the upper arm, I'd ask you simply to keep enough of an open mind to stay with me for just a few minutes- rather than exit this page in disgust. I hope I'll be able to illustrate just how much more versatile your thumb is than you probably realise, and show quite how much LESS impact and exertion is likely to result when your arm stops sending needlessly high levels of momentum into collision at the keybed. Yes- involving a notably pronounced movement from the thumb itself should actually be vastly more comfortable than trying to press the arm through a thumb that merely "supports" and I hope I can show you how to perceive this for yourself.
When you pressed into the table, what happened to the rest of your hand? Did it raise up over your thumb? If not, I'm afraid to say that this is a sure sign that you scarcely engaged the most useful activities AT ALL!!! Don't worry though- the details on how to introduce them are coming right up. If you did cause the rest of your hand to lift away, that's a promising sign- but how far did it go? Try going back to your starting point and simply lift up the fingers, as shown in example 1:
Don't press with your arm as you do so and don't even make any willful attempt to create pressure through your thumb! Start with it touching lightly and just think of lifting your fingers up and away. Did you feel your thumb starting to lightly engage- simply by lifting the fingers up? Try flicking the fingers up fairly quickly now (see example 2)- but remember to think up! Think of the downward pressure as being like a side-effect of lifting up- not as any kind of a goal. If the thumb feels "squashed" at all (either during the movement or once the fingers have stopped) make sure you start with a lightened arm and think of the hand's actions as being upward all the more. Sometimes try "waving" (keeping the knuckles high but moving the fingers back and forth) as in example 3. Particularly during this wave, be careful not to brace your arm. If it wants to wobble slightly in response, that's exactly what you need to be letting it get on with. Feel the sense of a loose "chain" that is free to sway slightly- extending from the thumb all the way to the shoulder.
Can you feel the slight adjustments that the thumb makes to remain balanced? While you should clearly perceive that downward pressures occur as an indirect result of your actions, they should never be especially large. With the right quality of movement at a piano, you don't actually need to exert a big pressure to achieve a full tone. I can honestly say that the very slight pressures that occur here (without so much as intent) are not drastically smaller than those required to make a healthy level of sound at the piano.
Anyway, if you're the impatient type you may already have jumped the gun and started applying this to the piano- and you may already be starting to get a better idea of the thumb's potential to produce tone. However, we've barely even started! All we've done is get the muscles to act in response to a flick of the fingers. The thumb is merely required to stabilise against a reaction in the opposite direction to the finger movement. It's possible that you'll have instinctively begun to involve the thumb's actions a little more directly than that, but we need to be sure. In the air now, try to differentiate between pulling the thumb down and away from the hand (example 4)- compared to the previous action of moving the fingers away from the thumb (example 5).
Alternate between the two relatively similar actions and try to notice what differences you can either see or feel in the results. However, be careful not to stiffen in a bid to immobilise anything. Retain maximum lightness and ease by going slowly and smoothly. If sympathetic movements still occur, that's fine- don't try to fight against them! Once you can clearly distinguish between the two, try flicking each movement out more quickly (examples 6 and 7)- but keep it very light again and don't fight the responses! If in doubt, it's better to keep it comfortable than to feel anything is being forced with needless vigour. Next up, try cocking the thumb back and extending it outwards (example 8). This will likely involve a slight rotation of the forearm (example 8).
Let's come back to the table. First remind yourself of the pure thumb "pull" by doing it in the air. Now let the table get in the way and feel how instead of moving the thumb itself, a reaction to that intention will instead raise the knuckles up (example 9).
The table "reflects" the movement in the opposite direction, like a mirror, in a manner of speaking. Make sure you still feel everything as an upwards action rather than downwards (with no jamming hard against the table) but try to feel how much more directly the thumb's action is now responsible for creating the upward motion compared to before. Try going back to lifting the fingers right up and reaching out (as in example 1), to see if the thumb gets more involved there too. Finally, try adding the act of extension. Think of much the same upward lift, but start with the thumb lightly bent and extend out forwards (example 10). Feel how when you lightly contact the table, everything is gently pushed back and away from that point- allowing everything to straighten itself out as the knuckles rise. Don't jam into the point of contact!
Finally, let's take this to the piano. Remember, you still need to think of lifting up though! It's very hard to retain this style of thinking, but you must not focus on moving the key down! For now, feel as if moving the key is a mere side effect of pushing AWAY, without anything resisting that motion away . Bizarre as it may sound, the slightest level of unconscious downward pressure with the arm is often what destroys the efficiency of energy transmission (this post gives a detailed explanation of why arm energy doesn't necessarily transfer to either the finger or the piano hammer, if you're curious). Depending too much on arm pressure also tends to crush everything together and create discomfort at the keybed. It's not impossible to add some in a useful way, but first you have to be sure that the thumb is playing its necessary role without jamming. The arm's role is to give your thumb an optional top-up- not to steal the show so frequently thumb never learns how to fend for itself.
Anyway, try playing that melody again. Is there much improvement in the quality of sound compared to before or in the physical ease of tone-production? Also, do you find habits wanting to come back? For now, you may have to make it extremely conscious, until your brain has a chance to develop an association between a big resonant sound and the activity that most easily achieves it- especially seeing as it feels like that activity is being aimed in what might logically seem to be the "wrong" direction! A great test here is to simply touch the underside of the thumb with the other hand while playing. Any remaining downward pressures will quickly be exposed by this. The underside of the thumb should only be touching (not pressing!) against your other hand. If you feel your playing arm is pushing even slightly, slow down and try to engage the thumb action from a passive arm that merely responds- not from an arm that presses. It's arm pressure that creates a big danger of impact and strain between the thumb and the keybed- not activity from the thumb itself. If you're still trying to lift the hand comfortably up and away when you reach the keybed, you simply cannot cause significant impact. It is only when the arm presses downwards or if the muscles are stiffly braced (or, worst of all, both!) that your thumb can be driven into a hard landing. (I shall upload another video rather shortly, to illustrate this action at the piano).
Next up, let's apply the same upward action to the differing context of a scale. For most students, the thumb is something to be feared in scales. It is often thought to be too "strong". However, this belief often causes an attempt to compensate that sees it go flaccid and unsupportive. When you see a bobbling arm in scales, it's almost guaranteed that this is because the student's arm sags down into every thumb note. The sheer inactivity of the thumb causes everything to slump down uncontrolled and jam against the piano. This typically results in an inconsistent sound that features as many heavy lumps as it does notes that barely sound at all. It's also harder to find the next position. Pressing down actively hinders the ability to realign. When the thumb works better, realignment becomes an automatic part of merely moving the key in the first place.
Here's a recently added video:
First I show a fairly lifeless thumb and the awkward wrist twist need to navigate deliberately between positions, without the proper thumb contribution. Then I show a slow sense of being opened around the thumb- not by moving straight to the side but in a larger curve. You can also wiggle the fingers, as earlier, or simply open them out. The feeling of realignment is an almost completely passive response to a very deliberate thumb motion, although the arm must be very light to react so freely and easily. It's not about having to work your thumb hard against weight. This is followed by a fast and almost functional version, with a quick throw of the fingers followed by instant alignment. Finally, the fingers no longer lift visibly, but the inner feeling is identical to the previous step- they still feel thrown up and over by the active thumb movement. It's like a gentle puff of wind "blowing" the arm over the top, into the new alignment. Similar as it might appear, it's nothing like the first one- where they are cranked sideways from a twist in the wrist. The arm is much more responsive to the thumb and nothing is being held into a fixed position.
Most people use overwhelmingly excessive downforce (without embracing the upward reactions) and thus struggle to open this freely. For this reason, take great care not to overdo the sharper actions and don't jam down for even a moment. However, once you have lightened up and learned to move the thumb freely, it becomes a real breeze. By the end, we should have the (seeming) paradox of extreme stability, coupled with a tremendous feeling of lightness and ease- that should carry as much into the other fingers as the thumbs themselves. Contrary to what many believe, the greatest ease of thumb movement comes when you give it a positive task to perform- not when you try to hold back. The problem with holding back a "heavy" thumb is that it removes all this assistance to easy realignment. We're left with the awkward feeling of having to consciously adjust from a wrist bend. With the right action, we simply open up naturally around the thumb, almost as if by magic. After work on these more exaggerated movements, normal scale playing should feel like the easiest thing in the world. The thumb should start to feel athletic and become one of the easiest fingers for controlling tone- not one to be used tentatively or with a sense of caution.
Anyway, I hope that at least one (and hopefully both) of the two different contexts of thumb usage will have become clearer and easier from this. If you've been surprised at how much powerful your thumb is than you realised, do be careful to build this into your playing gradually. Hopefully the thumb's action already feels natural (rather than a thing of great effort)- but it's still important to take care not to overwork muscles that are not used to doing so much (even if it already feels physically comfortable). However, if you didn't feel any great improvement (and are not already coming from a place of being able to execute lightning fast scales at the drop of a hat) I would consider reading some of my earlier posts regarding the arms and hanging on for future updates. The most likely hindrance to good thumb activity lies in arm tensions- which repress the natural responses and make the thumb work needlessly hard against resistance.
PS. I should acknowledge that the basic concept of bringing in a greatly active thumb is owed to what I have learned from Alan Fraser. While I think it's reasonable to refer to these as "my" thumb exercises, I should acknowledge that the ideas are very heavily rooted in the same principles as his "thumb-pushups"- which I strongly recommend.