The fundamentals of walking gravity, balance and falling
Centre of mass and centre of balance
Let’s be clear, nobody stands directly upright, and evenly balanced on their feet. Without exception, everyone’s body has its own unique way of standing, there are a multitude of twists, rotations, shifts and tilts, and no one stands exactly on both feet or has a perfectly curved and balanced spine. But what we all do is to develop a way of structurally integrating whatever individual adaptions we have in order to hold us together and upright. This ability to hold yourself together is especially important when it comes to walking.
When you are standing upright, your body has both a centre of mass and a centre of balance. Your centre of mass is always spread over the points of contact with the ground. So, if you are standing with both feet evenly weighted on the ground your centre of mass is 50% through each foot. In this position, your centre of balance is also evenly between your feet.
If you then move from one foot across to the other, your centre of mass will transfer, and your centre of balance will also correspondingly transfer from one leg to the other, and you will feel stable. However, if you lean in a counter direction, that is either forward or backwards you will soon feel that your centre of balance is being drawn out of your centre of mass. Gravity pulls on your centre of balance. In simple terms, as long as your centre of balance is able to ground itself through a centre of mass point you will be able to stay stable.
If you stand with your feet in a wide stance start slowly to peel one leg so as to transfer your weight to a single leg stand, then you will feel how your centre of balance is being drawn out of your centre of mass towards the lifting foot. You have two options, you can reinstate your leg and give back two points of mass, or you can integrate your structure and pull and hold your centre of balance on one leg.
Walking: dynamic balance
When you start to walk you first transfer your weight onto the forward foot, your centre of mass now transfers over the one foot in contact with the floor, and providing that you connect up and hold your structure on that one foot you will be able to hold your centre of balance on that foot. (Try it). However, if you release that structural tension that you are holding, your centre of balance will be drawn out of your centre of mass. Like taking away a leg on stool your body will fall to where the removed support was. Walking has been described as controlled falling, and in dynamic balance everyone’s challenge is to stay upright as you move.
This way of moving has however been developed and refined by mother nature ever since man moved onto two legs, so it really should be a part of our very nature. How is it then, that as people age walking becomes such a difficult operation to the extent that about 1 in 3 people over the age of 65 will fall in any given year? And is it really possible to help re-establish that natural movement, and if so how?
When you stand on one leg, your centre of mass is all through that foot, but your centre of balance is outside of the centre of mass. Your balance is only held because you have a structural integration in your body which temporarily keeps your centre of balance from being drawn out by gravity.
In a slow and measured fashion as you release the structural integrity in your body, gravity pulls your centre of balance out of your centre of mass, and you fall both to the inside and also to the front. All things being well you will have placed your other foot in front and your centre of mass will land into your newly placed foot. Your centre of balance will now be distributed across two points of mass and you will be stable. Most of that mass will be on the front foot, which is fine because in dynamic walking you are about to perform the same movement next using the other leg.
Kinetic energy and gravity
When you step next you change from two feet centre of mass onto one foot centre of mass as you lift the next foot, and as long as you are able to hold the structural integration in your weight bearing leg when you lift your foot, then your centre of balance will stay under your direct control. Now there is a kinetic energy from that falling motion and momentum which is stored in the landing stabilised leg, (like in a shock absorber in a car wheel) and then used to propel the walking motion forward in an efficient way.
It is easy to understand now that if you can’t hold the structural integrity in your body when you are on one leg, or you can’t structurally stabilize and absorb the kinetic energy from the falling motion in your forward leg when you move then your centre of balance will not be under your control, and falling is almost inevitable.
The way to re-establish your balance is by learning and practicing:
- How to structurally connect up your body when your weight is on one leg.
- How to release that structural integration in a smooth and controlled manner
- How to develop the ability to transfer weight from one centre of mass to another, that is from one leg to another.
- How to absorb and stabilize your body’s mass into each leg.
- How to store that kinetic energy and release it into a rolling efficient step.