The Science of Running
By Alex Hutchinson
Super Spikes
On the morning of his famous sub-fourminute mile in 1954, Roger Bannister went to the hospital where he was training as a junior doctor. There was a grindstone in one of the labs, which he used to shave down the spikes on his racing shoes to a fine point. “You don’t really think that’s going to make any difference, do you?” someone asked.
But Bannister knew otherwise. He’d had the spiked racing shoes custom-made to his own unique design, using ultra-thin leather and narrower-than-usual spikes to shave the weight down by a third, to just 125 g – comparable to the most sophisticated spikes of today. Every 100 g you strap onto your foot increases your energy consumption by about one per cent. “This saving in weight,” he later wrote, “might well mean the difference between success and failure.”
We’ll be hearing a lot about spike technology at this summer’s Olympics. A new generation of so-called super spikes from Nike, New Balance and other shoe companies has cut a swath through long-standing world records in track middle- and longdistance events. The resulting controversy echoes the 2017 debate about the fairness and legality of carbon-fibre-plated marathon shoes. The new spikes feature curved plates and resilient foam midsoles, reversing the obsession with lightness that Bannister’s shoes (which sold at auction for £220,000 in 2015) epitomized. But they also hammer home a point that Bannister and his peers never doubted: shoes make you faster, and some are faster than others.
The story so far
The super-shoe era started in 2017 with the launch of Nike’s Vaporf ly 4%, which lab tests showed reduced average energy consumption by four per cent, corresponding to an expected improvement of two to three per cent in race time. Both Eliud Kipchoge and Brigid Kosgei wore versions of the Vaporf ly in setting the current marathon world records in 2018 and 2019, respectively. Most of the major shoe companies now have models that replicate the Vaporf ly’s three main innovations: a stiff carbon-fibre plate, an unusually thick midsole and an ultra-resilient foam that returns a high proportion of the energy when it’s compressed and released with each step.
The curved plate attracted most of the initial attention: critics saw it as a spring that artificially aided runners, and called for such plates to be banned. But when scientists at the University of Colorado analyzed the shoes, trying to figure out how they worked, they concluded that the thick foam midsole was at least as important, serving as a “battery” that could recycle more energy from stride to stride than any previous shoe. World Athletics, the sport’s governing body, responded by imposing a maximum heel thickness of 40 mm for road-running shoes.
The corresponding track spikes started showing up as prototypes in 2019 track meets, and they incorporated similar elements, although World Athletics imposed a stricter 25-mm limit on midsole height in track shoes. But there was a key difference: on a track, no one saw stiff, carbon-fibre plates as unusual. Track spikes have always had a rigid spike plate under the forefoot, where the spikes attach, and curved full-length plates made of materials like carbon fibre have been used in spikes for decades. That left critics with a dilemma: shoes that seemed to give their wearers an unfair advantage even though none of the individual ingredients in the shoes were novel.
In a sense, the debate about track spikes helps to clarify the earlier debate about road shoes. Scientists aren’t sure exactly how or why the new spikes work. They’re not even sure how much faster they are, because the usual lab method of measuring energy consumption during running requires that you stick to relatively easy, aerobic running – which is too slow for a useful assessment of spikes. But on the track, we’re no longer
fixated on the technical question of whether stiff plates should be illegal, because virtually all spikes have some sort of stiff plate. Instead, it’s clear that the problem isn’t the specific technology; it’s the fact that this particular configuration works too well, giving an unfair edge when only some of the athletes in a race have access to the latest spikes, and devaluing the achievements of previous generations of runners.
Shoe ethics
In the 1970s, the Universit y of Waterloo philosopher Bernard Suits coined a now-popular def inition of sport: “the voluntary attempt to overcome unnecessary obstacles.” We all have many ways of covering 42k far faster than Eliud Kipchoge could ever dream of, but the meaning of the feat depends on accepting certain arbit rar y constraints, like “no roller skates.” The t ricky t hing is that those constraints evolve over time: pole vaulters use f ibreglass poles instead of bamboo; tracks are made of rubber instead of cinders. So neither extreme position – all change is good or all change is bad – is reasonable.
Where does the new breed of super shoe fit? On the basis of the technologies involved – a stiff insole, a thick midsole – I can’t see any reason to ban them. Retired University of Calgary biomechanics expert Benno Nigg has proposed that the geometry of the new shoes offers a “teeter-totter” effect that enables the forefoot to catapult the heel off the ground. It’s hard to see how authorities could effectively police the geometry of shoes to prevent designers from harnessing this effect. And they’re certainly not going to ban cushioned soles.
What matters more, given the rapid pace of change, is equitable access. As I write this, Nike’s Air Zoom Victory and ZoomX Dragonf ly and New Balance’s FuelCell MD-X seem to be ahead of the pack. There are rumours that Adidas and other companies will have competing models by the Olympics. Here’s hoping that pans out, because one of competitive running’s greatest attractions is the sense that it pits humans, not engineering teams, against each other. If so, expect a rash of national and world records this summer. Enjoy watching them, but don’t be surprised if the novelty starts to wear off.
For the elite athletes in Tokyo, unilateral disarmament isn’t an option. “Once an effective technology gets adopted in a sport, it becomes tyrannical,” sports ethicist Thomas Murray told me a few years ago. “You have to use it.” For most of us, though, the decision is more personal. If you’re trying to qualify for Boston, then you’re being graded on the curve of everyone else’s performance, so it probably makes sense to use super shoes. But what if you’re trying to beat your previous best from the pre-super-shoe era, or crack an artbitary time barrier, like the three-hour marathon? A purist might suggest that you should stick with the same old shoes – but the temptation to grab any edge available will be awfully hard to resist . Just ask Roger Bannister.