You oversimplified wrote:
Not really. Animals that run faster than us use springs so we're essentially trying to alter our conformation to duplicate their advantage. I
I am no expert in biomechanics or physics, although I do have an engineering degree, so I would love to understand more about how a spring would work to "create" energy. Not trolling, I really am interested.
If you're a mechanical engineer or an engineer who understood dynamics fairly well, draw a free body diagram of the whole foot as it contacts the ground. This will show you that all this "spring" nonsense about saving energy is more of a publicity thing than working technology.
Running shoes have always been about shock absorption so that your legs don't break down as quickly while running. The only spring-action taking place while running is from the calves (and hamstrings i guess but that's not important for this rant) during ankle flexation, while pushing off the ground. So that piece of carbon fiber in the sole is really only a fancy shoe support, unless runners have been generating force by bending their foot in half somehow...
And before anybody approximates the foot as a single point, just remember that the ankle is a joint, which means, any "extra energy" produced by these shoes is then transferred to the calf muscle which means more atp spent to resist a larger load.