When hands are hanging loosely at the sides of the body, the fingers are in a "natural curve," which is a perfect hand position. The finger are not extended but in their natural, relaxed state (see Example 1). (Natural curve varies from person to person.)
Try This: Extend your fingers straight, and keep them there (see Example 2). Within a few seconds, tension is experienced because the hands and fingers want to return to their naturally curved position. Naturally curved fingers make the ideal hand position for playing the piano. They are not to be at or "over-curled."
The hand should then be slightly opened through the palm (from the knuckle of the fifth finger to the inwardly curved first joint of the thumb). Fingers should not be stretched apart, and the top of the hand should be relaxed. Placing the hand on the crown of the head is another way to open or expand it.
When playing, the palms of the hands should feel "alive," similar to when the hand is ready to open a doorknob. It is not tense and not totally relaxed, but in a state of "readiness," ready to respond.
The "Arch" of the hand
In its natural curve, the knuckles (connecting the fingers to the hand) are higher than the wrist. This makes a "bridge" or "arch" that connects the thumb to the tip of finger five. The fingers and the angled tip of the thumb all become the same length with this curved arch in the hand (see Example 3). The thumb is angled (not lying flat) to support the fingers on the keys, and is played on the side tip (see Example 4).
A major support of the arch of the hand is a muscle that connects the thumb and finger three (see Example 5, arrow A). The arch is completed by finger five, which is one of the stronger fingers since it has its own muscle (see Example 5, arrow B). When playing finger five, it should feel "lifted" from the palm (see Example 6), not pressed down from the top of the hand, as shown in Example 7.
Firm nail joints
Nail-joints must be firm. Theodor Leschetizky, one of the greatest piano teachers of the late nineteenth and early twentieth centuries, insisted on this. Known for not having a specific method, "He required rock-like firmness of the nail joint. It is one of the few absolute principles he laid down." After interviewing numerous concert pianists, Harriet Brower wrote that, "Most of them agree that an arched [hand] position with rounded finger joints is the correct one...furthermore there should be no weakness nor giving in at the nail joint."
Attaining firm nail joints
Here are some ways to help develop firm nail joints:
1. "Knock" on a table, or the piano keys, until nail joints "feel heavy."
2. Make a circle by touching the tips of fingers 1 and 2, then 1 and 3, 1 and 4, and 1 and 5. Press them together to strengthen the nail joint.
3. Playing each finger one at a time, with the other hand, gently "push" on the nail joint that is playing to feel its firmness.
4. "Hang" on the edge of the keyboard with the nail joint of each finger (one at a time). Have someone shake the upper arm, keeping the nail joint firmly in place (see Example 8).
It takes time to develop a good hand position with firm nail joints. Patience and perseverance are necessary by both teacher and student. The reward is the ability to create beautiful music.