- About normal walking
- Energy use during normal walking
- Walking compensations for a physical limitations
- Walking with an orthosis or prosthesis
About Normal Walking
Walking is moving by taking steps at a pace slower than running. While energy is definitely consumed during this activity, it is minimized by the symmetrical advancement of body parts. This creates an efficient rhythm allowing energy to be carried over from one step sequence to the next when walking on a fairly level surface.
Discounting certain aspect of walking such as starting, stopping, or changing direction or speed, walking is cyclical. The most commonly accepted basic cycle is from the moment one heel strikes the ground until the same heel strikes the ground again. The amount of time that this cycle takes is easily measured clinically with computer assistance . This allows for a comparison of what the left leg is doing compared to the right leg.
DynamicBracingSolutions™ clinicians further break down this cycle to measure how much time each leg spends on the ground and how much time each leg spends swinging in the air.
Why is so little energy used during normal walking?
Discounting getting up, stopping, or turning, a lot of our normal walking activity is usually done in a fairly straight line. This means that from one step sequence to the next, there is some energy carried over. This minimizes the amount of energy that we use. Thus, all of our body segments (arms, trunk, legs, head) displace minimally and add to a primary, or net, force. The velocity or speed of our body during walking is sustained, if not constant. This is probably as close as we will ever get to Isaac Newton's concept of momentum as stated in the First Law of Motion whereby a body in motion tends to remain in motion.
Walking should result in as little energy consumption as the neuromuscular condition permits in an individual. Orthotic brace and prosthetic design and training should minimize any increase in the amount of energy consumed. Good design should have as a goal the conserving of energy and, where possible, the storing and release of energy to prevent excessive and early fatigue. This is not only desirable for polio or Charcot-Marie-Tooth patients but for any patient displaying deformities or mechanical deviations.
How many different compensations are there?
There are a great many deformities and functional deficits, but there is a limited number of compensations. There are only so many ways that the body can make gross compensations in order to balance and walk in an upright position. All of them require excessive energy use. Some of them may result in secondary deformities if not addressed. All or any of them identify the way you walk as abnormal.
Among the more common compensations are the following:
- Truncal deviations in which the trunk shifts to one side or to the other or moves forwards or backwards. This balancing strategy is horizontal in nature as about 70% of the body's weight shifts.
- Excessive hip flexion in which the hip muscles lift the entire leg against gravity, usually to compensate for a dropfoot or an ankle contracture. This functional strategy is vertical in nature as about 15% of the body's weight is lifted against gravity.
- Circumduction or a swinging of a leg to one side to advance the leg and clear the ground. This functional strategy is also vertical in nature, lifting about 15% of the body's weight. Frequently, however, it is combined with the following strategy.
- Circumduction of a leg accompanied by a shifting of the trunk to the other side. This is a classic seesaw application as the shifting trunk makes possible for the outward swinging of the leg on the other side when the hip muscles are weak.
- Hip hiking or lifting the pelvis on one side. This is a vertical strategy frequently used to assist the leg in clearing the ground.
- Vaulting or raising almost all of ones body weight vertically against gravity. This is an exhausting strategy frequently used to also help in clearing the ground on the other side. It is also sometimes used to regulate timing. By raising the body's weight during vaulting, the velocity or speed of the body decreases. This is sometimes necessary to allow the other leg to catch up.
Should an orthotic brace or a prosthesis address the compensations as well as the deformities?
Yes. If the design and training do not incorporate features for the compensations, it will not be possible to balance properly while walking nor will it be possible to sustain the velocity or the rate at which you are walking. Also it will not be possible to attain a normal way of walking.
Is normal walking possible with an orthosis or a prosthesis?
- In absolute terms, probably not.
- In relative terms, a normal walking appearance is often realizable.
Being fitted with a lower limb orthosis (brace) or prosthesis (artificial limb) does not at all guarantee that you will walk normally. It should, however, improve your walking. The design, fit, and alignment of the device as well as the subsequent training all contribute to the static balancing necessary to potentially achieve a normal gait.
The intended result of an orthosis (brace) or prosthesis (artificial limbs) is to prevent or correct deformity, transfer weight, improve balance, and increase the speed of walking. Various orthotic and prosthetic designs found in the marketplace today provide these results in varying degrees.
Some designs perform amazingly well; others not at all. And some just barely meet the accepted standards.