Posture has long been thought of in terms of standing and sitting and correct posture as the erect position assumed when one is under inspection, but posture should really be considered as the sum total of the positions and movements of the body throughout the day and throughout life. The above is the opinion of an orthopedic surgeon who leads an active outdoor life.
Good posture changes with age. The very young child is more like a four-legged animal than a man. As the child gets moving about, he is potbellied and sway-backed - that is, like an old horse with a sagging back. But gradually, as he approaches manhood, the belly becomes less and less prominent and the curve of the back lessens.
In the past the ideal standing posture held up to us was that of the soldier on inspection: the chest expanded, the shoulders thrown back, the toes turned out. This tense strained position is uncomfortable and inefficient. Who has ever seen an athlete perform efficiently with the toes turned out? The big toe is the part of the foot which does the work.
The argument for chairs designed for proper posture is based on the assumption that the occupants will conform their positions to the shape of the chairs, or vice versa. Children in their formative years are squirming organisms. They will not fit any shape of chair for long. Cats, the most efficient of athletes, always take loose slouchy attitudes when resting. The best quality of a chair would seem to be its comfortableness. It is safe to say that any posture taken temporarily while at rest is unimportant. It is only habitual bad posture which is harmful.
As the muscles are the only factor of posture controllable by the individual, exercises are the principal treatment. Sports are the pleasantest forms of exercise, and to be efficient at these it is necessary to apply the principles of posture in motion. For any of the muscles, the restful position, of course, is relaxation. But each muscle has its opponent. When you bend a joint as far as possible, you stretch the muscle on the other side. A position in-between rests both muscles. From this position each muscle is ready to do its work quickly and efficiently. Hence you see that when a person starts to rise from a chair, climb a ladder, run, walk, box or do any other active motion, his arms, legs, back and in general all his joints are somewhat bent and relaxed and thus ready for motion in any direction.
Proper attire helps this moving posture. The high collars of the old days are gone and the neck can now bend. Tight heavy clothing interferes with rhythmic movement.
To sum up: Don't expect your young child to have the posture of a man. If he grows up with a tendency to round shoulders and caved-in chest, give him setting-up exercises in loose clothing and remember that the moving posture is the important one, not that standing at attention for inspection.
Not only does proper posture in motion give us ease and conserve our strength but it is necessary for good balance. The other day I watched a lovely year-old child playing about. Seizing a piece of furniture, she would pull herself to a standing position and remain thus erect apparently until bored but not tired. Yet she did not walk. Why not, when she had plenty of strength and often wanted to get to another place? It is because the act of balancing is exceedingly complicated, requiring the teamwork of brain, eye, ear, muscles, nerves, and some remarkable sensations called "proprioceptive." This sounds tough but the word simply has the meanings of "proprietor" and "accept." The brain is just taking sensations from its own body.
This is how it works. You are standing upright but start to topple to the right. Instantly sensations in your muscles, joints, and skin telephone to your brain: "Get busy, he is falling to the right." If you are a tightrope walker, your brain in about a millionth of a second has told your muscles to pull you to the left. The muscles get in the game quickly and some of these same sensations tell them exactly when they have done enough and not too much.
The physical laws of stability are pretty well ignored in the human body. The big drug firms are nice people so I am sure that one of the largest of them will not object when I quote a paragraph from one of its articles: "Take a flexible, somewhat rubbery, oblong, irregularly shaped object weighing in the neighborhood of one hundred and fifty pounds and measuring something under six feet high, with a center of gravity two-thirds of the way up. Put this object in motion and try then to balance it on a couple of bearing surfaces each no larger than twenty square inches. Chances are that it will topple over and crash." The writer is describing a predicament that comes home forcibly in the later years of life when these millionth-of-a-second reactions have gone forever. Of course, people who may be classed as normal vary greatly in the delicacy of their balance. Otherwise circus acrobats would be out of jobs.