Saturday, April 4, 2009

The Foot " Part One

By Jonathan Blood Smyth

According to the evolutionary view of our biological history we have evolved from creatures which had a four-legged gait, changing gradually to our now very successful and functional walking pattern. Our bipedal gait has had several consequences. One is that our upper limbs have been freed so we can use our hands to do things within our visual fields, leading for worse or better to our dominance of the globe. Second is the necessity for our legs to take all the forces and effort of standing and gait, leading at least potentially to problems coping with such high levels of force.

Running, walking and standing are the functions of our feet and they did not expect to have to deal with skateboards, dancing, winter sports, heavy weights or sport. There is no avoiding the fact that feet are the ultimate place taking the weight and forces generated by the body, showing a balance of extraordinary stability and flexibility with both adaptability and strength. As a typical person may walk a hundred and fifty thousand miles while they are on earth this is a lot of stress, not including pursuing sports and other energetic pursuits.

However, the foot evolved to walk, stand and run. It did not evolve to do ballet, ski, skateboard, lift heavy weights or skip. The foot receives and copes with every pound of pressure the body exerts upon it in its many activities. The foot is extremely strong and stable, but also adaptable and flexible. It has to cope with a typical 150,000 miles the average person walks in their lifetime, with greater loads imposed by anyone who pursues an athletic activity or simply exercises regularly.

The key to how it is possible to put a greater load through our body than our weight is to consider the addition of speed to the equation. The amount of force involved is a product of speed and weight, with the forces increasing significantly as the speed of the movement increases. It is easy to understand this when thinking about the dreaded weighing scales, not a popular thought mostly. Stepping onto that scale you will see, for a second or so, the scale jumps right up beyond your weight then settles back to where you hope it might. To simulate the stresses of vigorous movements such as jumping, jump right onto that scale and see the scarily high level the dial gets to!

After considering the speed of movement we have to go back and talk about weight, not a favourite subject but one that involves much anxiety and stress and applies a considerable pressure. Our extra pounds are not just passengers hanging about, they make up an important part of the speed times weight equation. On vigorous movements that extra pound is multiplied many times, to stress our joints, ligaments, bones and muscles. This makes it harder to exercise the heavier we get, setting up a vicious circle where increasing weight leads to decreasing activity. At this point our bodyweight becomes a factor limiting our ability to exercise to reduce our bodyweight.

The other part of the equation mentioned above is our weight, that subject we are not keen on but which occupies such an important space in many of our lives, usually for negative reasons. Every extra pound we put on does not just sit their passively, it is multiplied many times when we indulge in various activities and this will make it progressively harder for overweight persons to exercise. This very quickly can become a self-fulfilling prophecy as increasing weight makes exercise increasingly more difficult. This way the people who really need to exercise find it less and less likely that they can do it.

The midfoot is made up of five bones of irregular structure and constitutes the middle of the foot arch, giving the foot the power of propulsion as well as the ability to shock absorb. The hindfoot is made up of the calcaneus or heel bone and the talus or ankle bone. The weightbearing calcaneus bears the tendo Achilles attachment and the tibia and fibula make up the ankle joint with the talus, constructing a very important joint for normal gait. - 14130

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