Being lifelong marathoners, we’ve long searched for the best running shoe. You can probably relate! In 2018, after years working for other running footwear brands, we started Vimazi with the idea of designing and making the best running shoe.
But what does “best running shoe” even mean? Given a deep background in math and science, we knew a physics-based understanding of running forces was necessary. So in 2018 we conducted a Forces in Running Study which looked at the timing, location, and intensity of forces generated while running. The research looked at a variety of paces and footstrike patterns for both women and men.
Two things surprised us: First, the impact force occurs and ends so quickly that it can’t help with propulsion. Second, the propulsion force is much greater than the impact force.
Since these facts were at odds with conventional wisdom, we set out to develop physics equations that defined running and running forces in a way that conformed with this new information. After multiple training blocks and countless marathons of math across many whiteboards, we developed a unified theory of running forces that aligned with Newtonian physics.
As crazy as it sounds, this had never been done before.
But running shoes have been studied for forever, haven’t they? Yes! Let’s discuss. As you're certainly aware, countless studies have seemed to show that super shoes help runners run faster. Unfortunately, these studies all suffer from a causation fallacy—we observe runners running faster, therefore it must be because of the shoes. But there's no direct link from shoes to better performances. What about smarter training techniques? Maybe it's better fueling during events? How about advancements in diet and hydration? Some of the studies suffered from self-reporting bias as well, which isn’t reliable and isn’t even science. Worse, most of the studies and descriptions of running and running shoes haven’t conformed with Newtonian physics. Last I heard we’re all still running on earth…but I digress.
We took our new theory of running forces and verified it with the experimental data from our Forces in Running Study. It was a huge and fundamental breakthrough. With the physics now proven, we were able to calculate the exact forces generated at different paces in the heel, arch, forefoot, and big toe.
It became immediately clear, given the physics and study data, that the midsole shouldn’t be thought of as one homogenous unit. To make a shoe that works in concert with the physics of running—in other words, a best running shoe—you need to think about the heel and forefoot as completely separate units. Our solution was to invent a foam disc we call a forefoot FastPod that responds to the forces you generate during push-off.
We also learned that runners generate a wider range of both impact forces and propulsion forces than we had thought. Those forces are intense at 5 minutes per mile (3:06 min/km) but much more gentle at 12 minutes per mile (7:27 min/km).
To study running forces and better understand midsole foams, we used a dynamic compression device to test the compression constant in the heel and forefoot of various shoes. Surprise! We found that midsole foam (it doesn’t matter what type) isn’t nearly as adaptable as we’ve all been led to believe. In fact, it turns out that it’s impossible for one midsole foam to respond appropriately and efficiently to the forces at all running speeds. Your midsole might be way too soft and therefore inefficient or way too hard and devoid of proper cushioning. With current running shoes, you’ll never know!
If you want a midsole that responds correctly to the pace you run, the foam density needs to be adjusted to address the precise forces at that pace. When we adjust the density of the foam in the heel and forefoot FastPod for each running shoe models, we’re matching the compression constant with the forces inherent within a specific pace zone. We call this density adjustment “tuning.”
All this means two fundamental things. First, the heel and midfoot need to be tuned differently from the forefoot to accommodate the differing forces. We solve this using a forefoot FastPod that’s tuned differently from the midsole foam in the heel.
Second, the heel and forefoot need to be tuned for specific pace zones in order to respond appropriately and efficiently. We solve this by making different models for different pace zones.
Pursuing the truth and understanding the physics paid off. By tuning midsole foam density between heel and forefoot as well as by pace zone for each of our models, we’ve been able to optimize cushioning and maximize push-off efficiency for every runner. We’re offering a more personalized running shoe, and at the same time democratizing cushioning and performance for all runners.
The only way to get the best cushioning and the most energy out of your shoes is if they’re tuned for the pace you run. And that’s exactly what we do. Yes, it’s a radically different way to think about running shoes, but it’s the right way. By doing this work we’ve definitely closed in on our goal of creating the best running shoe.
Now you’re welcome to continue running on non-tuned shoes with generic cushioning that probably aren’t correctly responding to the forces you generate at your pace. But we think running in shoes personalized to the way you run is pretty cool. And if you can get better performance and a perfectly cushioned ride, all the better.