Put Your Best Foot Forward

Who remembers James Fixx these days? At the end of the 1970s, the man was a celebrity, a star, because he started a mass movement. The wave spilled over into many countries. People—infected with a desire to run—ran in fields, woods and meadows, on paths along rivers, on sidewalks, and if there weren’t any, in the street.

Molding compounds based on polyamide 12 meet the high standards runners have for their shoes.

Stefan is 50 years old and a marathoner. His best time: 2:56:32. His weekly totals are between 50 and 80 kilometers. When training at this intensity, running shoes have to take a lot of punishment, sometimes going on hard asphalt, sometimes trails through the woods, sometimes paths along river banks.

Stability and low weight:

Marc Knebel, Lifestyle key account manager for High Performance Polymers, and himself a runner, explains, “Complex chemical structures need to be transformed into tangible applications. We’ve accomplished this successfully by working closely with well-known sporting goods manufacturers during the development of athletic footwear using molding compounds based on polyamide 12 and polyamide 12 elastomers from Evonik. Polyamides play a large role in the design of athletic footwear. The focus is essentially on semi-crystalline materials from the top-third of the polymer pyramid, so these high standards can be met. Compared with other polyamides, molding compounds based on polyamide 12 are characterized by high dimensional stability, constancy of properties in fluctuating environmental conditions, and low water absorption.”

Even when hobby runners don’t splurge on custom shoes, their standards for this important piece of “athletic equipment” are high. The shoe needs to fit (manufacturers refer to this as “correct fit”), it needs to be comfortable, and it should support a tendency to run naturally.

So what is required of athletic shoes, and what can the polyamides from Evonik offer? Beyer responds, “Athletic shoes need to be tough, which means the polymers need to meet very tough mechanical requirements, both static and dynamic ones. And the polyamides also need to be able to stand up to the effects of the weather. The shoes need to give a feeling of effortlessness—giving sprinters wings, long-jumpers a tailwind, and long-distance runners legs that float. Because the polyamide 12 molding compounds have a density of just under one, the weight savings for a 100-meter sprinter would be one kilogram.

The sole material absorbs energy when it is deformed, some of which is returned to the runner as an impulse via a spring effect. With VESTAMID® the difference between the absorbed and returned energy is very small compared to other materials.

The most lucrative part of the business is in mass-market running shoes and that is where, says Beyer, “our VESTAMID® has been incorporated into many shoes. The magic word is cushioning.” Cushioning is supposed to keep the feet as comfortable as possible on hard surfaces without neglecting athletics, and while supporting the work of the muscles and joints.

The market is always changing, and new trends pop up all the time. The shoes the 244 marathon pioneers wore running through Berlin’s Grunewald in 1974 are now fit only for a sports museum. Training versus race shoes, cushioning, cutting-edge transparency and design, new requirement emerge every season practically—which means new challenges for manufacturers and their suppliers.

And Fixx, the man who got us all running? He died of a heart attack while out on a run at only age 52. But his notion of running as an ideal sport—because it was simple, healthy, and inexpensive—continues to fascinate millions of people around the globe.