The human body is a marvelous thing, and our spines are feats of mechanical wonder, composed of dozens upon dozens of vertebrae, all of them interlocked and then held together by cartilage and ligaments. Of all the mammals, we have the smallest base of support, the highest center of gravity, and the heaviest brain, making it appear as if we were balancing a bowling ball on a fragile column. Yet somehow it all works due to how brilliantly we are put together. Sometimes, however, stress or bad postures or habits can interfere with this natural state, resulting in problems that yoga can not only solve, but greatly improve upon, so that all kinds of energy are liberated.
The truth is that if you were to remove all the muscles that support the spine it would still hold itself erect due to intrinsic equilibrium. This is because it is built in such a way that between the bone, ligament and cartilage it stacks up and keeps the spine in a neutral, erect posture. However there can be muscular forces at work that can interfere with this balance, and yoga can help correct these bad postures by putting us through movements and correct postures that help us ease the muscular interference. Once this is done correctly, once that energy that is being used to cramp and control muscles around the spine is removed, it can feel as if we have actually gained that energy, as if our reaching intrinsic equilibrium has created a great source of vitality when in fact it has simply removed a block from our natural mechanics.
In short, by practicing the correct postures and movements of yoga, we can learn to correct bad habits and poor postures and in doing so remove the blockage that we may have unconsciously built around our spines, allowing the bones to return to their true neutral and intrinsic equilibrium, suddenly liberating that energy and making it feel as if we had gained a huge bonus when in fact it was always within us, but simply being directed in the wrong way.