The remarkable foot
Feet are one of the less attractive parts of the body and yet are vital to our very existence. The leg and the foot are the levers that enable us to move around.
The foot in particular is also highly complex. It contains no less than 26 bones joined by 107 ligaments and linked to 19 muscles by a series of tendons in order to create movement. There are nerves that link it to the brain which tells it what to do and blood vessels that carry the minerals and proteins that maintain the tissues protecting its central bone structure. Understanding how it operates is fundamental to producing good footwear.
Bone structure
The bone structure of the foot is divided into three groups.
- Tarsus with seven bones, including the calcaneum or heel bone.
- Metatarsus with five bones and comprising the middle of the foot.
- Phalanges with 14 bones which make up the toes.
Bone itself is formed by the deposit of calcium phosphate which forms a light but strong honeycombed structure. It is a long process which continues into the very late teens. A child’s foot, therefore, has little real structure, so correctly designed lasts and carefully fitted shoes are essential. This bone structure also forms two arches. The longitudinal arch falls between the heel bone and the head of the first metatarsal. Its height varies from person to person with some people having particularly high arches and insteps while its absence in some is the cause of flat feet and other foot problems. The transverse arch lies across the base of the metatarsals when the foot is relaxed. Under load, it flattens out and the foot becomes wider as the bones spread.
Feet and motion
When we walk, the foot provides support for the body and propulsion to move it forward. It works in a rolling fashion with the outside of the heel hitting the ground first. As the forefoot contracts, the foot rolls inwards and the point of greatest pressure follows the outer edge of the foot up to the outer joint. As the heel lifts to flex the foot, the pressure transfers across to the inner joint and finally to the big toe as the body is propelled forward. (This explains why it is so difficult to walk if you hurt your big toe). Exploiting this foot action to the maximum is a key factor for sports shoes.
An average day may involve up to 10,000 steps and the transmission of surprisingly large forces through very delicate and fragile areas. Excessively long periods of standing, running or jumping and walking on uneven surfaces can therefore cause problems, especially if a person is overweight. When walking, feet come under the impact of one and quarter times body weight, so extra weight means ankles, bones and joints come under increased pressure.
They also need to provide more shock absorption for the body. That in turn means more wear and tear and a greater likelihood of foot or ankle pain. In addition, the bones of the foot are held together by ligaments, so extra weight can force joints apart and make these ligaments stretch. This can change the shape of the foot so that it becomes wider and the arches to begin to collapse. Beyond the age of 80, the foot becomes more flexible and the arch much weaker due to the ageing process.
Footwear must therefore always be functional in order to work with the foot rather than against it. This might seem obvious, but fashion often tries to ignore this and results in footwear that has the potential to cause damage to the foot. It is therefore essential that as well as providing good fit and comfort, a shoe must cause as little disruption to foot function as possible. The last shape in particular has the most profound effect and must therefore take into account the type of person who will wear the finished footwear and the purpose for which it will be worn. Sports shoes, for instance, require a different set of parameters to dress shoes, as do children’s to adults’, and men’s to women’s.
As we age, the way we walk tends to become more cautious. The foot spends more time in contact with the ground so that less and less time is spent resting on a single leg which helps older people to cope better with uneven surfaces. The downside is a reduction in walking speed as they now take shorter steps. This is more pronounced in women than in men. The width of the step is also increased and the foot itself is not raised so far when it is lifted off the ground. As a result, it tends to be carried forward closer to the ground surface so increasing the risk of tripping, a common cause of falls.
The foot is indeed a remarkable part of the body and one which we all too often take for granted until something goes wrong. It is also one that is frequently abused through wearing ill-fitting, unsuitable or poorly designed footwear. Much of this is down to the choice of the wearer who in an age of online shopping has no professional to advise them.
However, there are still instances of designers slavishly following the dictates of fashion without due regard to the requirements of the foot itself. There is no real excuse for this. After all we only have one pair of feet to last a lifetime.
CREDIT: SHUTTERSTOCK / ELIZAVETA GALITCKAIA
