Amazing Feet " Part One"
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.
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.
We have many activities we like to partake of and the foot's job is to allow us the wide variation in strength, stability, flexibility and power to achieve these by accepting, adapting to and exerting the necessary force. The foot is divided into the hindfoot, the midfoot and the forefoot. The phalanges and the metatarsals make up the forefoot. The phalanges are the small toe bones, three in each except for only two in the big toe. There are five metatarsals, recently featuring in the broken feet of important football players, making up the main part of the length of the forefoot.
Five non-regularly shaped bones make up the midfoot, occupying the central part of the arch of the foot, giving the foot its ability both to propel itself as well as to absorb shocks. The ankle bone (talus) forms part of the hindfoot and with the fibula and tibia makes up the very important ankle joint, allowing a normal gait pattern. The heel bone (calcaneus) makes up the rest of the hindfoot, a weight bearing bone which takes the forces of the Achilles tendon.