Changes

* {{H:heelcounter}}. The heel counter is part of the overall plastic skeleton.

The Energy Boost is immediately comfortable, with a light, flexible upper with no noticeable seams. I'm thankfully Adidas has used a traditional tongue and laces, rather than a sock style upper or Velcro fastening. And while the sole has the traditional raised heel, there is none of the multi-density foam or other intrusions that are so common. I think a lot of people will buy the boost because of its immediate comfort, but stay with it for its extraordinary characteristics.

=Adidas Boost Foam=

The Adidas boost uses a new type of foam in the sole that has more bounce and is more resilient. Adidas demonstrates this extra bounce by dropping a steel ball on their new foam and EVA, the industry standard foam. Because of the extra energy return in their new foam the ball will bounce much higher than on EVA. However, when we run our feet do not bounce off the ground, but have a short period of sustained contact, often called the 'stance phase'. So when your foot lands, it seems that the boost foam would return the landing shock back up your leg rather than absorbing it, which is less than ideal. It would be good to see a study that looks at how the boost foam changes the stresses on knees and hips compared with a standard running shoe. Regardless of how the bounce impacts your running, the increased lifespan of the new foam is appealing. Having a shoe that lasts longer is obviously good, but Adidas also claim that the new foam is more consistent through most of its lifespan, rather than gradually decaying in the way EVA does. Adidas also claims that their new foam does not change characteristics in extreme temperatures like EVA does.