How do super shoes make you fast?
For a writer, I feel unusually qualified to answer this, having worked on two separate academic research projects related to it.
The simplest answer is one many runners have heard of: carbon-fiber plates. One of the studies I worked on built these plates for sprint spikes. We worked in a manufacturing lab, a lab that housed an enormous number of other team’s projects, such as a project building real satellites to be sent to space.
The beauty of carbon fiber is its unusual combination of strength and being lightweight, which is the first answer to why it works in a running shoe—it doesn’t weigh you down. There’s more than one way to manufacture a carbon-fiber plate, but one way is to take a flexible carbon-fiber mesh, form it around a mold matching the shape of a running shoe, brush resin onto it, and heat it. It will then harden and become something like a really stiff insole, giving the shoe a sort of spring effect, and that’s the key to the whole thing. This can improve running efficiency.
The other study I worked on dealt with the other side—how do you tell how much stiffness is the right amount to create the spring effect? In that project, I worked with a prominent running shoe company to test 6 different levels of stiffness. Well-trained runners would come into the lab (very different than the other lab—this one just had treadmills, computers, and efficiency-testing equipment, such as would be used to test a VO2 max; also a cooling fan because these poor souls particpating in the study would be wearing an oxygen mask and other equipment and the stuffy lab would become very hot). The participants would run in each pair of shoes corresponding to the 6 levels of stiffness on 6 different days. Their efficiency was tested by measuring their oxygen levels and other advanced metrics. This data would be analyzed to determine which stiffness was optimal for the greatest number of people.
In contrast, professional runners often receive the same testing to personalize a certain stiffness for themselves. Olympic marathon gold medalist and former world record holder, Eliud Kipchoge, was among the first high-level athletes to receive this personalized attention, around 2017.
Those early Nike super shoes had a dramatically increased stack height of their soles to accommodate the plate and the geometry of the shoe, landing at around 40 mm. Recognizing that there needed to be a limit to how far this technology could be taken, World Athletics set 40 mm as its legal limit for road racing stack height, allowing for all the super shoes already designed to stay eligible.
Tradition vs. technology is an ever-present debate in any major sport but is much more serious in a sport defined by times and records, with no meaningful way to compare current running stars to the legends of old (or even the ones 15 years ago). And just as significant is that compared to other sports in which both sides receive the advantage, in running, it’s you versus track; you versus the trail; you versus the pavement. Only you have the new shoes.
