• Greg Marshall

Testing the Latest Injury-Proof Running Shoes

What some of the latest developments in running footwear might mean for all of our success in the sport.



I grew up with the barefoot generation. As a highschooler, I remember looking at two of my cross country teammates skeptically as they geared up in the locker room. One of them was pulling on a pair of Vibram FiveFingers, the most out-of-place looking “running shoe” I had ever seen. My other teammate had opted to do away with the institution of footwear altogether for these last few months of cross country practice, and he’d begun to develop thick calluses under foot as he pursued a “healthier and more natural” way of running.


In the late 2000s and early 2010s, a new wave of running philosophy had taken hold. Minimalism was king. Inspired by the native American tribe of the Rarámuri detailed in the bestselling Born to Run, runners scrambled over one another for pairs of Vibram Five Fingers or, better yet, to make their own shoddy sandals at home. The prevailing belief was that the less shoe under your foot, the better and more injury-free a runner you could be.


The trend didn’t last long as eventually, runners who’d taken on the minimalist philosophy started getting injured just like their footwear-bearing competitors. In the months and years that followed, academic studies started to trickle out showing that no, we’re not really any better off ditching the cushion.


Hoka Tennine

Today runners are finding themselves immersed in a very different message. Companies like the world-renowned Hoka One One are bringing us what they claim we really needed all along: maximalist running shoes. Athletes are trading their tired old trainers for inches of ultra-thick, ultra soft, air-injected midsoles that at first feel more like a moon shoe than something you’d work out in.


There hasn’t been a lot of information on this new breed of shoe for runners to fall back on, marketing claims and anecdotal evidence aside. Recognizing the blindspot, Drs. Brianne Borgia and Julia Freedman Silvernail of the University of Nevada Las Vegas and Dr. James Becker of Montana State University in Bozeman, began conducting rigorous studies to test the viability of the newest “injury-proof” running shoes.



Impact and Repetition


Borgia et al. conducted two studies utilizing a similar protocol but with different objectives. The first one sought to characterize how the demand placed on a runner’s leg by a footstrike in maximalist shoes compares to others. In other words, what forces were involved? The second study sought to understand the differences in coordination pattern of a leg through the stance phase; what kind of motion was involved?


It’s a difficult thing to precisely measure what a person does while running without influencing that person’s running. For example, even if you can measure the forces applied to your knee while running with equipment strapped to the outside of it, it’s pretty likely that the extra baggage is going to change the way you run. Instead, biomechanists opt for noninvasive measurement devices like commercial-grade motion capture cameras and impact-force-measuring treadmills (not to mention a heavy dose of post hoc physics calculations). The team then tested three common shoes representing a minimalist (New Balance 1400), traditional (Nike Pegasus), and maximalist cushioned shoe (Hoka One One Bondi), and each participant spent a few minutes running at an easy pace in each shoe.



Rearfoot biomechanics
Rearfoot motion patterns (Morley et al., 2010)

In the background, Borgia, Becker, and Silvernail all have some pre-existing notions of what kind of factors result in running injury-- primarily impact and repetition. They quantified the effects of impact as leg stiffness (essentially how the leg absorbs shock) and the effects of repetition as coordination variability (the differences in how the leg moves through one stride with every other stride in the test). To sharpen their picture of what changes might be resulting from maximalist shoes, the team’s analysis broke these two measurements down a step further. Leg stiffness was parsed into hip, knee, and ankle stiffness to understand each joint’s contribution. Three coordination relationships were also used- how the rearfoot (heel) moves relative to the tibia (shin), how the shin moves relative to the knee, and how the knee moves relative to the heel.


It doesn’t take an expert to recognize that impact and repetition are prominent features in running, but if maximalist shoes are doing their job, we’d hope as Borgia and her team did, to see a reduction in both of these with comparison to our minimalist and standard shoe options.



The Preferred Running Pattern


One of the more notable insights gained from the studies conducted by Borgia et al. was that rather than reducing impact to the leg, impact attenuation shifts a bit for the maximalist option by comparison to the other shoes. The hip and knee reduced in stiffness, moving through a larger degree of motion as they were loaded, and the ankle was more rigid, passing the force on up the leg to the other joints. What does that mean for chance of injury? It’s hard to say for sure, but the extra work being done at the knee and hip with the maximalist shoe actually indicates potential increased risk for injury to the two joints.


Hip and knee stiffness aside, Borgia’s team generated a mountain of data characterizing how runners subconsciously respond to the shoes on their feet. In all of the data, the result that sticks out most is that really no result sticks out.


Coordination Variability Histogram
Consistency in motion patterns for shoe type and joint/shank coupling (Borgia et al., 2020)

For all of the variation of shoes, the number of different participants, and the different forces and movement relationships measured, maximalist shoes were unremarkable. The maximalist option made no difference in whole-leg stiffness with comparison to the minimalist and traditional options. The knees, shins, and heels of runners coordinated the same stride pattern in the maximalist option as in the others, and with no reduction in the repetitiveness of impact. In other words, stride variation went unchanged.


Those results seem a bit deflating, until you realize what they mean for the message the big-cushioning industry is filling our shoe stores with. The promises of reduced risk for overuse injury, or even better injury recovery, look to be in question.


Still, Borgia and her team note that we’re left with more questions than answers about the performance effects of maximalist cushioning. Perhaps, they note, we could be seeing an artifact of how new shoe designs interact with a concept known as the preferred movement path paradigm (Nigg et al., 2015). The paradigm suggests that we can instinctively correct our familiar motion patterns to what we’re used to, even in a new shoe that’s trying to disrupt that pattern. If we assume that is in fact what we’re seeing, the questions get increasingly interesting and complex as to what implications these new designs could have on muscle activation, athletic performance, and risk for injury.



So what does this mean for the era of Maximalist Running? It’s still too early to say if there is any actual benefit or detriment that can be attributed to ultra-cushioning shoes, but it’s pretty clear that these shoes won’t instantly elevate us to a superior, injury-free stride. For the most part, your body continues to do what it has always done when it’s running.


Borgia, Becker, and Silvernail have illuminated how the body reacts the moment it steps into one popular maximalist shoe, but they also note that there’s no telling how biomechanics could be impacted over the course of a training cycle, or even how things change as a maximalist shoe wears out. For me the takeaway is pretty clear: the human body excels, as it always has, at adapting to changing stresses. For the time being, it seems like it’s still best to choose what feels right on your foot whether that’s inches of cushioning or just millimeters of rubber.




References

Brianne Borgia & James Becker (2019) Lower extremity stiffness when running in minimalist, traditional, and ultra-cushioning shoes, Footwear Science, 11:1, 45-54, DOI: 10.1080/19424280.2018.1555860

Brianne Borgia, Julia Freedman Silvernail & James Becker (2020) Joint coordination when running in minimalist, neutral, and ultra-cushioning shoes, Journal of Sports Sciences, 38:8, 855-862, DOI: 10.1080/02640414.2020.1736245

Nigg, B. M., Baltich, J., Hoerzer, S., & Enders, H. (2015). Running shoes and running injuries: Mythbusting and a proposal for two new paradigms: ‘preferred movement path’ and ‘comfort filter.’. British Journal of Sports Medicine, 49(20), 1290–1294.



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