This is usually not useful. Unless we are talking about an arm pose like Crow or Plank, it will not help us to focus on the hands, elbows or shoulders. Here is why…
The majority of postures are about the spine.
The arms do not move the spine. The muscles that move the spine are the muscles that move the spine: abdominal and back muscles. So if we are trying to move the spine, it won’t help us to focus on the arms.
TWO COMMON MISUNDERSTANDINGS
There are two common misunderstandings at play here. The first is that the spine can change length. It can change shape, but this is not the same as the spine itself actually growing longer.
The spine is a fixed length. There are vertebrae and discs that make up the spine. The spine itself cannot lengthen. One side of the spine can lengthen, but it does so by the other side of the spine shortening. This is what we do in backward and forward bends. In a backward bend the front of the body does get longer, but that’s because the back gets shorter.
If we want to change the position of the spine, we have to do so one side (front, back, left, right) at a time.
The second misunderstanding is confusing shoulder elevation for spine length. In the picture above, the spine is no longer than with the arms down by the side. It is only that the shoulders are elevated, or to say it another way, the shoulders are shrugged up by the ears. This is trapezius engagement. With the arms overhead and the trapezius engaged, it may look like the spine is longer, but in fact it is an optical illusion. It is just the arms and the shoulders that have moved.
Often, it is said that reaching with the arms will help bend the spine. But reaching with the arms moves the shoulders. Some shoulder muscles, namely the trapezius and the rhomboids, do attach to the spine. But they get their stability from the spine in order to move the shoulder blades. These are not muscles that change the shape of the spinal column.
To put it simply, the spinal muscles move the spine. The arms, shoulders and hands do not. In spinal postures, do not worry about lengthening your spine or using your arms. Try to put your focus on the muscles that move the spine.
