Adidas has introduced the model "1", a shoe that provides intelligent cushioning by automatically and continuously adjusting itself. It does so by sensing the cushioning level, using a sensor and a magnet. It then understands whether the cushioning level is too soft or too firm via a small computer. It adapts with a motor-driven cable system to provide the correct cushioning throughout the run. It works like a human reflex nerve.
The nerve is a magnetic sensing system, where the sensor sits just below the runner's heel and the magnet is placed at the bottom of the midsole. On each impact, this sensor measures the distance from top to bottom of the midsole (accurate to 0.1 millimiter) gauging the compression and therefore the amount of cushioning being used. About 1000 readings per second are taken and relayed to the shoe's brain.
Underneath the arch is the shoe's brain, a microprocessor capable of making five million calculations per second. Software written specifically for the shoe compares the compression messages received from the sensor to a preset zone and understands if the shoe is too soft or too firm. Once it has determined if the cushioning level is appropriate, it sends a command to the shoe's muscle to make a change.
A motor-driven cable system is the shoe's muscle. The motor, housed in the midfoot, receives the brain's instructions and adapts by turning a screw, which lengthens or shortens a cable. This cable is secured to the walls of a plastic cushioning element. When the cable is shortened, the cushioning element is tensed and compresses very little. When the cable is longer, it allows the cushioning element to compress further, making the shoe's ride softer. A small battery, which is replaceable and lasts for 100 hours of running (the normal life of a shoe), provides the motor's power. The changes are gradual and happen automatically, so all the runner notices is that the shoe feels right during an entire run.
Three years in development, the shoe was a secret project, known by only a few people even within Adidas. The Adidas 1 shoe was officially presented on May 2004.