Balance is something we use consciously and unconsciously throughout our day. When we walk, change posture, work, and even when we sit still, our bodies move through different postures that need to be maintained if we want to live comfortably. This is what balance is; the ability of our body to maintain a posture for an extended period of time,. There are many factors that feed into how proper balance, or equilibrium, is achieved, and to go through all of them would take too much time. However, it's worth exploring the relationship that good balance has with good posture, because the two are quite closely interrelated.
Posture has previously been defined as an alignment of the body where the strain on bones and muscles is minimised, and which allows a person to perform an activity. The ability of the body to maintain that posture is the ability of the body to control its Center of Mass. The Center of Mass is the average position of all the matter in the body. In a standing person, the Center of Mass is a few fingers' width in front of the Sacrum; deep within the hips. In standing, gravity acts on the Center of Mass, and the force vector produced by the action of gravity results in the Center of Mass lying above the middle of the feet, which is how most people stand. The action of gravity on the Center of Mass produces the Center of Gravity, which is a vertical line drawn through the Center of Mass, which represents the downward pull of the Earth's gravity on that point. In standing, the position of our feet creates an area called the Base of Support; an area within which the Center of Gravity can move without causing the body to topple. If the Center of Gravity moves out of the Base of Support, then we need to move our feet or grab onto something to compensate.
When we move between postures, such as sitting, standing, walking and kneeling, the size of the Base of Support, as well as the position of the Center of Mass changes. In standing, the Center of Gravity passes through the Base of Support. In sitting, the Center of Gravity passes through a Base of Support created by the seat, which is why we can remain upright even though our feet are in front of our torso. In walking we move one foot in front of the other and the Base of Support constantly changes, but we maintain our posture by having our Center of Gravity sway dynamically, balancing the forward and sideways movement through every step, in a coordinated rhythm of action between the muscles in the legs, back, and the arms. In life, in sport, and at rest, our bodies constantly control the action of our Center of Mass, Center of Gravity, and Base of Support to keep us in whatever position we want to occupy, whether we are sitting still, standing up, or in motion.
There's more to it than that, though. All of the activities described; walking, sitting, standing, and kneeling are all the result of individual action; they are internally produced by the person, in this case by their brain. The body has a complicated set of feed-forward, feed-back, instantly-revising and constantly-monitoring systems to keep ourselves aligned, and the brain is responsible for it all. The brain also works to compensate for actions produced outside of the body. If you've ever ridden a train that was standing room only, stood on the deck of a ship that was rolling, or walked across a pontoon bridge, your body has had to address the effect of forces acting on your body from the outside. These external forces also affect our balance, and the speed with which we can adapt to them is called Agility. So balance isn't just about helping to maintain postures, but in adapting to changing external circumstances which might throw us out of those postures.
These adaptations are the result of automatic reflexes that are controlled by the brain. The brain receives information from the eyes, the muscles, the joints, the inner ear, and processes all of this information faster than the blink of an eye to produce responses that save the body from damage or displacement. Some of these responses are so fast that they bypass the brain entirely; taking place independently of any conscious thought and sometimes happening before we are aware of them. This just goes to show how important it is for our bodies to be able to change position in a moment, faster than a person can snap their fingers.
While these responses can be instant, balance also needs to be maintained over longer time periods. Over the span of a human life, human anatomy changes as a consequence of sustained forces, sustained behaviours, and sustained postures. One example is the gradual forward-bending of the upper, middle, and lower back as a consequence of ageing and weardown of the spine, as well as a lifetime of working on tasks on desks, tables, or benches. As the ribcage rolls forward atop the spine, the Center of Mass and the Center of Gravity shift forward, creeping from between the arches of the feet to the balls of the feet and the toes. This produces the foward-bent posture that is stereotypical of geriatry, in which older men and women become reliant on external supports like walkers or frames. These external supports fulfil the same end as a chair in seating; they increase the size of the Base of Support, and provide a larger area within which the Center of Gravity can move without causing an adverse outcome. In this way, the balance needs of the human body changes over the course of our lives as the anatomy of the human body changes, and the individual capacity to respond to internal and external demands changes as well.
Balance is more than being able to stand on one leg. It is an ongoing, active, and continually revised process which works to measure the internal strain and external obligation imposed upon the body by acts of living and the environment, and address them with controlled, precise reactions using human anatomy. It relies upon sensation, perception, and action to produce exact ends. It changes over the course of our lives, relying upon our muscles, bones, joints, and our nervous system to function. It is a topic far too involved to discuss thoroughly in the span of a single blog-post, but it goes to show that posture and balance are closely interrelated. Good posture facilitates good balance, and good balance allows the maintenance of postures that let us go about our lives in a minimally effortful and maximally enjoyable way.
Good balance is good posture. Good posture is good balance.
You cannot have one without the other.