Curved fingers and stiff hands at the piano: what curved fingers really mean for your hands. Resting your hand on a table, not on its task. Normally your fingers are a little curved, but they are not stiffly rounded either. So curved fingers at the piano should be approximately the shape of that. This does not mean a perfect hand shape, but it means each finger pressing down each key with control without tensing the wrist, arm and shoulders.
Often a student hears “curved fingers” and instantly tenses the entire hand. The knuckles go up, the fingers grip each key, and the wrist gets stiff. This can make any melody even slow feel tiring. It is better to think of each finger as rounded, but soft. Each fingertip touches each key, the wrist stays soft and the shoulder is not lifted with each note.
There are a few other useful hints. Before you start a section, let your arm hang loosely by your side, then bring the hand to the piano in that relaxed manner. Put five fingers on five white keys in a row (no notes played). Note the shape of the thumb and the little finger. Is the wrist very high, very low? Is one hand shape better than the other?
Now play, very slowly, five successive notes, one finger at a time, using fingering 1, 2, 3, 4, 5. When each key is played, lift the finger up from the key. Play very quietly. If the notes are loud because you are pressing too hard, then try to play much softer. It is not necessary to strike the piano keys for a good tone, even in the early stages of learning.
Usually, problems with fingers become apparent when each finger moves independently. Fingering 4 seems weaker, the fifth finger straightens, the thumb twists under. Try a slower rate and look for any unnecessary movement. Each finger is moving, but the others must not freeze (this should not be necessary) or lift up, and the fourth and fifth fingers should not stiffen. It is usually much easier to control very slow, soft movements.
Hand shapes will vary somewhat for different pieces of music (a simple melody does not require the same hand shape as a chord or a scale). Still, avoid completely flat or very stiff fingers. If the wrist aches, the forearm gets tight, or the shoulders go up, stop and reset. This course must not be about learning tension.
One indicator that your hand is moving well is that you can remove the hand from the keyboard and place the fingers on new keys without looking and repositioning the wrist, which is flexible, and the fingers can reach each key easily and the notes are even, without pushing. The rounded hand shape at the piano is not an aesthetic for piano technique, but a part of a relaxed technique that makes music reading and melody playing less difficult.