I read a post today in a forum where a pianist spoke of having problems keeping their hand open but relaxed in the Chopin etude op 25 no 1, stating that they gradually accumulate tension that becomes too great to function. The likely reason for this is something that tends to show up the most in the wide intervals of this etude. However, it also applies to basically everything in technique so I thought I'd give a quick summary here, from foundation techniques to advanced.
People often say that stretching is bad and that you should think of opening instead. Often, it's also suggested that even any opening should be released as quickly as possible. I agree that thinking of "stretching" can suggest undue effort, but it's not magically solved merely by changing the word. We should look at the what the difference actually is, in more precisely defined terms. Also, I fundamentally disagree that you should always try to release any opening as quickly as possible. Done the right way (without needless effort) only the most extreme intervals urgently require the hand to avoid staying open. Anyway, what is the fundamental difference between "stretching" and "opening"? See here, on the simple third, between fingers 2 and 3.
When the arm exerts unnecessary pressure on the first note, even something so basic can feel strenuous. The pressure into the keybed both limits the ability of the arm to move and also reduces mobility of the fingers themselves. When the arm is free to move sideways with the next finger, however, it's effortless. The finger still "reaches" to a degree, but the arm can now assist it rather than hinder it. This is a quality that you want to begin to instill from your very first foundations of piano playing.
When we move up a level to a broken chord, the same issue applies. If the hand is held in position, as I show first, it will feel very strenuous to try to apply arm pressures to each individual key. There will be a strong sense of stretching and straining. However, it's generally completely unnecessary to counter this by thinking that you shouldn't stay in an open position. Just move better. If you apply the same smooth quality of arm movement, you can drift sideways in a continuous motion. See the difference in the fluidity of my demonstrations. First I move *to* each key and try to rest down. Then I move *through* and beyond each key, with constant arm sideways arm motion that doesn't stop for any individual note.
This will alternately take the thumb and fifth fingers off the keys, as they follow the arm movement. There will also be subtle changes of feeling between fingers, but my second and third fingers *never need leave their keys*. The hand is still open. If you feel any sense of tension from keeping that distance, it's almost a certainty that your real problem is about individual pressures into the keybeds, just the same as in the first exercise. A degree of exception might sometimes apply for smaller hands. However, if you want to do this quickly, then you can't afford to entirely lose the shape, regardless of hand size. The problem can't be fixed simply by running from readiness for such an ordinary interval. You need to remove *the excess arm pressures that cause you to strain*. The job of the arm is to follow through and beyond the new notes, not to stop to push down or weigh directly into any finger.
Last, I show some of the etude. Here we have a slightly different issue that will reveal a huge truth about both of the prior examples. If we try to feel the weight of the arm pinning the melody note down (as is often advised in traditional ideas), the arm is now basically immobilised again. The open position likely feels stretched and strained, once more. For this to work properly, you need your arm to be fully mobile around the fifth finger. Start by moving the arm around a clear contact in the keybed. Although the fifth finger still creates an essential join for the arm, it isn't a weighted feeling. It comes from ensuring *the fingertip actively pins that key down*. Arm pressure will stop the arm being truly free to move around that pivot and we get the same sense of strain that was caused before.
A finger has to be especially active to keep the feeling of an arm join. There is a constant process of adjustment, in order to ensure that the arm movement doesn't simply pop the finger off the key. These adjustments should serve to keep the level of pressure steady, no matter where your arm goes. If you have made the mistake of taking arm weight explanations at face value, you may find yourself letting the key pop up at first. However, if you want to be mobile and free with your arm, you're going to have to learn to adjust within the finger itself. Once you do so, the arm is again free to drift sideways through the following notes, with the melody clearly pinned down at all times. This simply cannot be accomplished if you think of keeping the keys down with literal arm weight. Notice how big the difference is between my example of getting stuck in weight, vs freeing the arm to go with the moving notes.
If you go back to the more basic first examples now, the ideal technique should come from exactly the same place. Whenever the arm is moving sideways, it's the job *of the fingertip* to keep the previous key pinned safely down, while the arm is moving sideways, and not weighing down. Watch how much the original finger has to adjust on that original basic third, when the arm is free. It's not a transfer of weight but rather a transfer of fingertip *contact* (which is chiefly sustained via constant adjustment within the hand). The weight is being carried sideways to prevent burden, in relation to the support of active fingers. Intent to just relax often actively prevents this from happening. Fingers that don't intentionally pin keys down with extreme clarity *cannot* fully free the hand to open, or the arm to move. Significant whole arm pressure occurs instead and causes all the problems shown.
The only reliable way to avoid "stretched" feelings is to be have very active control over depressed keys, coupled with constant sideways arm movement. Even slight breaks in the ongoing movement may allow the arm to weigh down on the fingers and create that feeling of exertion. With clearly grounded keys and steady sideways arm motion (without bobbling up and down) any necessary relaxation will almost certainly develop for itself, without risk of associated heaviness or instability.
If you get this technique right you will not have to fear a hand that generally stays open and neither should you feel "stretched". Obviously every hand has a limit. However, unless you understand how to use the fingers to keep keys grounded (while the arm drifts freely around the comfortable contact) you will not have any sense of where your easy limit actually lies.
Also, here is a video I previously made of the full study. To be honest, I'm not especially keen on the playing. However, you can see the sense of how the left hand thumb largely stays out- rather than feel that this is something to retreat from.
