Today's sports shoes are genuine high-tech products compared to previous versions. The many different materials used to manufacture the shoes make them lightweight and stable. These materials enable the shoes to be tailored precisely to suite the style of running, the customer’s expectations and the various running disciplines. All this can be confirmed with a look around the development laboratories of sports shoe manufacturers: Test subjects run over sensitive pressure measuring plates which analyze and evaluate every step. High-speed cameras film the movement patterns and the heel-to-toe motion of the feet in the tiniest detail. All this information goes into the subsequent shoe design, which enables athletes to achieve new personal bests - and also offers recreational runners optimal running conditions.Manufacturers are permanently on the lookout for cutting edge technologies and innovative materials. adidas is also constantly further developing its running shoes. The company, headquartered in Herzogenaurach, Germany, has been supported by BASF materials experts for more than 20 years. Using BASF's new foam Infinergy, adidas has now developed the Energy Boost, a thoroughly new running shoe with unique spring and cushioning properties. Its outstanding feature is the midsole, the central element of every running shoe. It is made from a new particle foam which absorbs the shock impact on the foot during jogging, while simultaneously cushioning the foot. The high rebound effect of the material provides the runner with an energy return not offered by any other running shoe.
Infinergy is made of expanded thermoplastic polyurethane, in short E-TPU. "E-TPU is manufactured by foaming the starting material, TPU granules," explains Dr. Uwe Keppeler, material and process developer at BASF. "After pretreatment with pressure and heat, the individual granules measuring up to five millimeters each are blown up like popcorn." In the process, its volume increases tenfold to produce oval foam beads with tiny, closed gas bubbles inside. "These sealed air cells make the lightweight foam beads very elastic and provide the desired rebound effect. The individual beads can be imagined as being like tiny footballs: The more air they contain, the better they bounce and rebound back," says BASF research scientist Dr. Frank Prissok.
