Most of the older will remember the rubber-soled plimsolls that were traditionally worn in PE lessons throughout most schools in Europe. These were available in any colour you liked as long as it was black or white.
These have been replaced by air cushioned, gel filled capsules with superior technical performance. They come in a variety of colours, shapes and forms and are purchased as much for their appearance as their performance.
The ground-breaking manufacturing technique that allowed the development of the plimsoll was called vulcanization, which is still used today. This process uses heat to meld rubber and cloth together. Sulfur is used during the process.
Plimsolls were revolutionary at the time as they provided comfort, were lightweight and allowed the user to move around silently. Plimsolls became known as sneakers and were sold on a mass scale in America as early as 1917.
In the four years since the last Olympics in Athens technology has moved on somewhat and has definitely moved on since the plimsoll days.
Trainers and sport shoes have evolved, we have different shoes for each event and each pair of shoes is manufactured from a variety of number materials chosen because of their individual properties to put strength and flexibility where it is needed most. Materials such as Kevlar which is ten times stronger than leather, leather or canvas which is both thin, stable and of a low density, foam blown polyurethane which gives a shoe extra cushioning and thermoplastic polyurethane which make a shoe both strong and pliable.
As technology has evolved scientists have developed new composite materials which work together to produce a better performance than that of the two or three separate materials.
Differing materials offer different properties such as stability; offering resistance to twisting and warping. When weight is applied to a material over a period of time it will creep (flatten out and spread).
Some materials are used for their elastic properties, the ability to flex and bend when force is applied and then retain its original shape when the force is removed. Finally, some materials are chosen for their density which can be explained as the amount of matter in an object has per measurement of space, these materials are generally used for shock absorption.
Polyurethane is a unique material that offers the elasticity of rubber combined with the toughness and durability of metal. The flexible type of polyurethane is used to make upholstery, mattresses, earplugs, chemical-resistant coatings, specialty adhesives and sealants, and packaging. It also comes to the rigid forms of insulation for buildings, water heaters, refrigerated transport, and commercial and residential refrigeration. It is used in the manufacture of sports shoes because of its lightweight shock absorption properties as well as being pliable as well as having great torsional and bending strength. Kevlar is one of the most important man-made organic fibres ever developed. The fibre possesses a remarkable combination of properties that has led to its use in a variety of commercial products since its invention in the 1970’s. The fibres of Kevlar consist of long inter-connecting molecular chains produces from poly – paraphenylene terephthalamide. Kevlar offers high tensile strength with a low weight, structural rigidity, low electrical conductivity, high chemical resistance, low thermal shrinkage, excellent dimensional strength, high cut resistance, flame resistant and self extinguishing. Pretty versatile really!
Spiked running shoes have been around for over 100 years created by the British company Reebok in the 1890’s. The spiked shoe was developed out of necessity. The founder of the company enjoyed running and wanted to develop a shoe that would increase his speed.
In 1925 a company called Adi Dassler now known as Adidas created a range of shoes with hand-forged spikes. They offered a range of shoes for different distances. The company used the strongest and lightest materials available at the time to make the running shoes. Adi Dassler’s brother went on to found the Puma sports shoe company.
The involvement of science and technology in the 1970’s sports shoe manufacturers employed experts to conduct research into how humans run. They also investigated the shock effect to the body caused by the collision between the feet and the ground. Their finding helped to develop new, improved sports shoes.
Their research found three types of running styles:
This is where the heel of the runner makes contact with the ground and the foot travels in a straight line as it moves forward.
This where the heel hits the ground but this time the foot moves to the side as it travels forward. It refers to the inward roll of the foot.
This is where the heel hits the ground and the foot rolls outward.
In modern times such materials as foam, silicon, air or gel have been added into trainers, these have been used to create cushioning systems in modern running shoes.
In the 1970’s a plastic called ‘ethylene vinyl acetate (EVA)’ was developed. This material revolutionised the construction of sports shoes. It was made up of tiny air bubbles that provide cushioning and absorbs shock. This material is injection moulded into shapes, which serve as heel supports.
Nike’s Air technology, which used a gas-filled bag of air inserted in the sole of the shoe to cushion the impact of running, first appeared in 1979. The pair of sneakers was named; Tailwind and these technologically advanced air-soles had provided a good foundation for which further Nike advancements are based on. Since then, athletic shoes have become increasingly specialized and prices for various sneakers have grown in accordance to the advances in technology and its value-added features. Some shoes sold in the 1980’s even included a pump valve so you could inflate or deflate the heel on your shoe as if they were bicycle tyres.
Following the introduction of Nike shoes , a technical breakthrough occurred in 1972 when Bill Bowerman, while studying the pattern on a waffle iron, came up with a great idea – waffle soles. Bowerman then cooked some rubber in his waffle iron and glued it to the bottom of a pair of shoes, which he later gave to athletes to test. The athletes came back with great reviews and the sneakers were well received in the market. The patented outsole revolutionized running by offering better traction in a lighter-weight, more durable shoe.