From concept to creation: the Vimazi journey

In 2017, around the time Nike was working on their Breaking-2 project, founder Scott was struck by an early morning thought while jogging to the track for his interval workout. It was 5 am on a dark, drizzly Tuesday morning. The thought hit him like this: he bet he could design a running shoe that did a better job of returning energy if he engineered the midsole to respond to the forces placed on it while running. He was only half-right. Yes, the forces generated change with how fast one runs. No, you can't manipulate a shoe to return energy in running. Why? Scott was to discover that running isn't the bouncing motion many have modeled it to be. It's a controlled, choreographed sequence of two legs that expend energy to get each stride just right. Inserting energy return into this motion violates the laws of physics. That's a big problem for energy-return advocates. Just a brief aside, in an otherwise very long post; Scott is a lifelong runner and he's spent his career making footwear for runners. Only to say that thinking about making shoes wasn’t a random Tuesday morning thing. 

Could there be a way to lose less energy during a stride? Perhaps help the joints articulate more efficiently or with less torque? Or improve the timing of muscle firing? Could certain foam properties or other materials influence how the body works and save a few Calories? The answer turned out to be “no”, but it took a while to get there. 

Like everybody else in the world and the hundreds of published papers, Scott assumed that running incorporated spring-like motions. And if springs were involved, then maybe there would be a harmonic resonance associated with particular stride lengths and cadences (i.e. paces). If you could engineer a shoe to match a resonance frequency, then you could get much more energy return. Or so the thinking went... 

Meanwhile, Scott started working with his high school running friend John to come up with the best way to tell their “resonance frequency means more energy return with pace tuned shoes” story. The story improved and the partnership clicked, so John and Scott decided to start Vimazi. After incorporating, they rallied a few friends and family members to invest in the company as they pursued the idea. 

At the same time, Scott worked on getting the formulas to do the engineering so he could build a prototype shoe and test it. He read every research paper and book on the subject, but nobody had published formulas to predict forces; there were only incomplete models to relate springs to running. Not to be stymied, Scott started working out the math and physics for himself. But he found a big problem: When he used real numbers as inputs (there are lots of force measurements published), he couldn't get a result that made any sense. What he means is that the properties of a spring in a shoe didn't result in anything that looked like the running measurements that anyone else had made. His numbers for resonance were off by a factor of 5. That's a gigantic discrepancy, and it was a low moment for him. Either he didn't know how to do the simple math for damped harmonic motion (which anyone can lookup online), or he was barking up the wrong tree. Hand on forehead! How does he break the news to John and the investors? 

Back to the drawing board. If it isn't harmonic motion, (that’s what you get when you bounce on a spring) then what’s going on? They aren’t talking about what happens inside the body, they’re talking about a shoe made of a simple bouncy material. If energy return is equal to harmonic motion, and if harmonic motion doesn't result in anything close to real-world measurements, then what is energy return? 

Another thought struck, and it struck hard. Maybe there’s no such thing as energy return in running. Maybe there is just shock absorption and propulsion. And if so, can a shoe be engineered to have a beneficial effect? 

Yes it can! But the plot thickens, because human feet are very peculiar. You thought this was going to be easy, right? Sorry. 

The total energy to move your body (a mathematical equation involving time) is part of the problem. How the forces are transmitted through your feet is another story. You won’t be surprised to know that there is a difference between what happens under the heel and under the forefoot. Humans have this big bone, the calcaneus, and an anatomy that lifts the heel off the ground halfway through the stride. It’s called plantigrade and is very different from dogs and cats (digitigrade). It is also very different from an artificial leg made for running that has a single pad as a “foot”. Since a shoe midsole only reacts to the forces directly on top of it, there are different forces on heel of the shoe than on the forefoot. Dramatically different. Here is the absolute key to the whole subject: the amount of energy on the heel at impact is significantly less than the energy pushing off the forefoot. They can determine the relative forces in the heel and forefoot as matters of pace, strike pattern, cadence, and terrain. Shock absorption turns out to be related to the ratio between heel and forefoot. Nail down that ratio and you can engineer how much shock to absorb. 

Shock absorption matters a lot to runners because repeated shock causes aches and pains. For Scott, the holy grail of running shoe design is to ease the stresses that cause pain and may lead to injury. He figured that stress-relieving shoes would be a perennial favorite. Good news investors! With this understanding of the physics of human running, the mission of Vimazi went from chasing an imaginary dream to delivering something of exceptional value: health and happiness. 

Stage two was to put the theory to the test and actually engineer a shoe and test it. And then Covid hit. They had countless delays in designing, prototyping, and commercializing their first six models. They’ve heard all about the supply chain slowdowns, and they suffered from that for sure. It didn’t help that they were tiny and unproven and couldn’t visit their suppliers and manufacturing partners in China. 

As the delays extended, they needed something to focus on, so they spent their time writing and publishing an interval training book, Running in Circles. They also built a unique training plan app called RunCrush, which was well-received on launch though they’ve had to back-burner it for the moment as they focus their efforts and watch their bank account. 

Meanwhile, the rest of the running world has been convinced that ultra-thick shoes with bouncy foam and carbon plates make you run faster. Some even say it’s a form of cheating. All without theory or proof, only causation fallacy. (We won’t digress into the fundamental problems with the analyses of marathon finish times or with the experimental designs in the running economy studies.) 

Despite the interminable supply chain delays, they were able to develop the initial styles, tuned for different types of people (fitness runners and walkers to elites), and test them against their math equations. The data store a trove of new insights, all of which are predicted by the math. But the best part has been experiencing the benefits of more shock absorption without compromising on stability. 

Every iteration along the way needed to be carefully tested. They spent a lot of time running on each model, and fine-tuning the fit, feel, and ride. Eyelets, heel components, toe design, laces, midsole finishing, and much more had to be reevaluated numerous times. By the end, the shoes have been tested in the Boston, London, Portland, and San Antonio Marathons, as well as in countless smaller races and training runs by runners of all abilities. 

Successful San Antonio Marathon in the Z50s

Finally, after almost five years, the world’s first tuned shoes have been completed and are on the way to their warehouse near Detroit. Woof! As they wait for them to arrive, John and Scott are looking at each other wondering what the next leg of the run is going to look like. They can’t wait.