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A coach for the British cycling team, “Team Sky” used a term “Marginal Gains” to try to explain significant performance improvement jumps for his athletes.  We can say this concept is essentially all about finding that extra edge (or series of edges so to speak!) for a boost in speed. A collective cluster of little optimizations that may add up to being very significant performance improvements. Whether or not those “optimizations” may be competitively legal or not is a story for another day!

Let’s consider Eliud Kipchoge’s sub 2 hour Marathon event: Besides having a flat, looped course with ideal weather conditions, other adjustments (not necessarily legal for an official world record or marathon major type of race) were made:

  1. He had a rotating group of “fresh” pacemakers in a specific V-formation for ideal drafting benefits.  
  1. Fluid bottles were handed to him by a person on a moving bike every 5km.
  1. He wore a new carbon fiber plated shoe design that stirred up a controversy of what may or may not be considered “legal” by the IAAF as well as fueling a discussion of regulations (mainly around a 40mm thickness limit and not having multiple, separated carbon fiber plates within a single shoe) 

So let’s focus on point #3: The technology of carbon-fiber plated shoe designs and possible gains from that.

Unless you’ve been living under a rock for the past 2 years or so (or just don’t follow the roadie and track scene  😆), there has been a shift with times dropping on a massive scale. From runners in the US Olympic Marathon Trials and half marathon world records, on the roads to new track records at 5km and 10km, people all around the world are breaking their personal best times by significant margins at an exceedingly high rate. What has been the single biggest change in distance running in the past 3 years? Shoe design we think. Specifically, the use of a curved carbon fiber plate within the thick shoe midsole made with a “bouncy foam.”

The name of the game with these shoes is trying to maximize a higher percentage of energy return (i.e. less energy is lost) with each step. Much like the physics behind how a coil spring transfers energy, the “spring like” return force of a bouncy foam sandwiching the flex of a curved carbon fiber blade (so to speak) has shown to generally be a very efficient mechanism for transferring energy: saving some strain on the muscles and tendons in the runner’s legs, but also improving running efficiency on a flat uniform surface when compared to traditional non-carbon fiber plated shoes. 

There is also a huge variable with individual “responders” in terms of running form and foot/gait mechanics that greatly influence carbon fiber shoe technology benefits. Here we are talking about your foot pronation, how you land, and how the angles in your ankle joint, knee, and hip interact with forward and upward propulsion. On the roads and track however, we’ve seen a fairly consistent and steady drop in times and records with the introduction of this kind of shoe technology. The real question though is: Does carbon fiber plated shoe technology have a place in the MUT Running world? – and will it have the same effect? So far, we have seen runners like HOKA ONE ONE’s Hayden Hawks lower Jim Walmsley’s legendary JFK 50 course record by nearly 3-minutes wearing (at least on the final toe-path and road miles) the carbon fiber Rocket X model. 

The North Face has released it’s new carbon fiber “trail shoe” design in the VECTIV. One of their sponsored runners , former UTMB Champion Pau Capell, time trialed the UTMB course in 2020 supposedly wearing this model – however his time in the new shoe design (21:17) was almost a full hour slower than his winning UTMB time (20:19) from 2019. Maybe not the best endorsement for the new product, but also not really revealing of anything considering an n=1 sample size and the fact that there inevitably different weather on the day and that perhaps the excitement of a real race was not there! 

So we’ll admit there’s not enough concrete scientific and real data yet in the MUT Running world, but it appears on the surface [poor pun intended] that the more technical the trails are with rocks and roots as well as steep uphills and downhills, then the less this new shoe technology is going to actually help improve running economy (efficiency). This may also be magnified at the relatively slower speeds run of these kinds of races anyway. On the flip side, carbon fiber shoes may actually inhibit performance because one may find themselves launching off a rock at an awkward side angle – or getting too much vertical oscillation on a steep uphill!

And of course these “weird force vectors” may or may not twist your ankle on uneven terrain. We’ve seen hard plastics like “rock plates” being used in trail shoe designs for decades. However, they are often mainly strategically placed in the toe to ball of foot area and are not fully integrated into the length of the midsole like many curved carbon fiber plate road shoe designs. Again, depending on the exact design of the carbon fiber plate like it’s curvature and thickness – as well as the type of foam material it is sandwiched within, this may or may not work well with your individual biomechanics. But throw in uneven terrain encountered on technical trails and you have a myriad of variables that will influence how the shoe design actually performs. 

Join the Discussion! Do you think carbon plated shoes (and associated foam technologies that they are often sandwiched in) are going to improve your times and efficiency on the trails (or hurt your times…or hurt you)? Which kind of mountain-ultra-trail courses may or may not be appropriate for these kinds of shoes?

Keep on trottin’

-The MUT Running team