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Understanding gait

There is no clear understanding in Medical or Sports Medicine texts of the way the lower limb, the levers that moves us over the ground, actually functions in it's contact with the ground when we walk or run. There has been a great deal of side-on two dimensional work but none that view the lower limb front on to gain a three dimensional perspective. Different texts I examine describe foot function in running/walking in a significantly different way. The most impossible version is in Brukner & Kahn 2005. A well regarded sports medicine text Petersen & Renstrom also has an impossible model of foot function. It obviously depends on who they have been observing. A more possible description can usually be gained talking to a group of seasoned runners who have a general idea of leg and foot function in running. Some will even be aware that they should roll in a few degrees at the fore foot but roll too much and it causes them injury problems.

Still not correct but the closest to an ideal model was described in a Biomechanics text (Kreighbaum, E., and Barthels, K.M., 1985). These authors also explain that we all have very different function. They point out that a tendency to view what is commonly occurring in the population to be normal is not correct. In looking at the posture and walking/running functions of humans, " Normal alignment does not necessarily mean ideal alignment for what is normal is a measure of what occurs on the average in the population not necessarily an ideal measure. In fact, most people do not have ideal alignment for one reason or another."

In fact I make the point that all of us are an individual variation of our own in every aspect such as size, shape and appearance. This is so with our inherited skeletal structure with it's individual variations and asymmetry in structure which gives us our faults in posture. This means that any normal healthy human being's locomotion over the ground is likely to be faulty and cause injury or wear. That is in fact what actually happens.

The way to identify what is an ideal model of foot and limb function during walking/running is not only to observe apparently healthy individuals who appear to walk or run with symmetry but to analyze that movement based on having studied the joints involved and decide the alignment required for healthy function. That is to have the joints aligned in their planes of movement to not suffer excessive wear and the limb aligned as a stable structure to withstand the forces of gravity acting from the ground up through. Once this is achieved the muscles/tendons attached to the structure will also be seen to function without the micro tears/stiffness usually accepted as normal for athletic activities or the occasional significant injury, tightness or tears usually labelled as overuse.

In a correctly aligned leg, the forces act straight through the joints with no tendency of ankle or knee collapse. The muscles only need to power us along and stabilize at a very low level. If the person has misaligned foot contact and suffers any excessive foot roll during the stride, the leg turns, ankle and knees turn and collapse sideways, hip turns excessively. The rapid forceful change in leg alignment creates wear to the joints and tears fibres in the working muscles. The forces are great and cannot be resisted by the muscles especially because it is repeated on each and every step.

The left hand illustration (a) (Brukner & Kahn) is said to illustrate weight bearing alignment of the lower limb with the ankle and knee aligned with the iliac crest. It is incorrect as alignment like this would have a person collapse inward and suffer forceful leg rotations with the leg swinging out widely and they would be exhausted after a few steps. This further illustrates the confusion that still continues in traditional ideas.

The right illustration (b) shows a correctly aligned weight bearing structure with forces acting up from the foot through the joints of the legs to the upper aspect of the hip socket. This is the alignment required to function correctly.

 

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