Posture at the workplace, Part 2
Muscle activity, balance and nerves
In the last newsletter we introduced the importance of correct alignment of joints. This article looks at the relationship of muscles, balance and nerves.
Muscle activity
There are two kinds of muscle, each with their own function. The first kind, postural or slow fibre muscle, is for holding us in the correct position. The other kind, movement or fast fibre muscle, is for moving us. Slow fibre muscle gives us control, fast fibre provides power; ballet dancers have control, footballers have power. Using fast fibre muscles to control tends not to be effective.
Even postural muscles will not hold positions for any length of time if they are not fit, a good reason in itself for sedentary workers to take exercise. The phrase "muscle tone" in physiotherapy refers to the amount of fibres in the muscle firing at any one time. Even in repose, some fibres are firing, the muscle is ready to go. Only when a body is dead is there no muscle tone! The amount of muscle tone in a posture is largely a function of the amount of support being provided. At an extreme, a person lying on their back has a wide support base, so minimum muscle tone. At the other extreme, a person standing on tiptoes on one leg has a very narrow base and so needs maximum muscle tone in perfect alignment.
Balance
A contributory factor to holding a posture is balance. Balance can be used in two ways when talking about posture. It can mean the balance of opposing forces. For instance, are the muscles holding the shoulders back strong enough in comparison with those pulling the shoulders forward? If not, then a round back is likely to be the consequence. Secondly, it can mean balance in the sense that if it is not right, the person falls over.
A person with good muscle balance will be able to hold an unstable position for longer, because the movement muscles are less involved. A person with poor balance will move a lot and have to use the movement muscles to try to get back to balance, these muscles will get tired quickly and the posture will be lost.
Nerves
We control our movement through our nerves. Messages are passed in both directions between the extremities, the muscles, the joints to and from the brain. If this passage of information is disturbed, we do not have proper movement. Nerves are physical entities and just as subject to maltreatment as bones and muscle; they can be affected by blows, by stretching, by pressure, by twisting. They pass between muscles, bones and joints along paths developed, like the rest of the system, during evolution. So it follows again that if alignment is not right, the nerves may be affected.
Would you like to read Part 1: Introduction; What is posture?; Joint alignments
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