Josh Kerr Smashes Mile Record in Custom Supershoes and Speed Suit

This weekend, twenty-eight-year-old Josh Kerr ran a mile in just three minutes and forty-two point six-six seconds. He smashed a record that had stood almost as long as he has been alive. A stunning performance at the World Athletics Diamond League competition saw Kerr shave nearly half a second off the mile record set by Hicham El Guerrouj back in 1999.

What was the key to this incredible success? Experts say the secret lies in his shoes, clothes, and naturally strong stature. Kerr ran his record-breaking race in a pair of one-of-a-kind supershoes specially designed for his feet and running style. Dubbed the Brooks Hyperion 222, these unique shoes feature a unique profile for an ultra-aggressive ride alongside extra-stiff carbon plates and lightweight titanium pins.

During the race, Kerr also sported a speed suit shaped to his body and covered with tiny laser cut perforations to boost cooling and aerodynamics. However, none of this would matter if it weren't for Kerr's above-average size and strength that allow him to make the most of this new technology. In a stunning performance at the IAAF Diamond League athletics competition, he shaved nearly half a second off the mile record set by Hicham El Guerrouj in 1999.

Since the mile record was set over twenty-seven years ago, only one person has even come within a second of matching Hicham El Guerrouj's record of three minutes and forty-three point thirteen seconds. However, the Scottish five-time global medallist didn't just surpass this seemingly untouchable target; he shattered it. Kerr shaved over 2.6 seconds off his previous personal best to set a new world record that could stand for many more years to come.

While this wouldn't have been possible without Kerr's own athleticism, experts say that he had a serious helping hand from cutting-edge technology. Dr Brian Hanley, an expert on athletics biomechanics from Leeds Beckett University, told the Daily Mail that the shoes contributed considerably towards breaking the record, although it is difficult to put a value on this. The shoes are the interface between the athlete and the ground and the less energy is lost during each of those interactions, the better.

In their scientific quest to break a long-standing World Record by a legend of the sport, the Brooks team were hugely successful in combining scientific and technological know-how with the specific needs of an exceptional British athlete. According to Dr Hanley, the most important part of the supershoe is the stiff carbon plate embedded in the sole. These act like a tiny springboard, ensuring that more energy is returned into the runner's stride with each step.

That means that more of the power generated by the athlete's muscles goes into moving them forward, so that they can run faster for longer. Carbon plates are the same type of technology that controversially helped Sabastian Sawe to shatter the sub-two-hour marathon limit in London earlier this year. Dr Hanley points out that this is especially important for racing spikes since the thickness of the sole is only allowed to a maximum height of twenty millimetres under World Athletics rules, half of what is allowed in road racing.

To boost these benefits even further, the shoe is built with an aggressive curved profile shaped to mimic the bottom of a bike tyre. For a jogger or long-distance runner, that profile would actually make running harder, but for a middle-distance runner up on their toes it helps drive their power forward even more efficiently. Danny Orr, senior director of product development at Brooks, told Popular Science that this creates an effect almost like he's running slightly downhill.

Mr Orr explained that this shape was chosen after eight years spent measuring Kerr's performance and running style and was designed specifically with a record-breaking race in mind. Kerr also wore a specially designed speed suit featuring tiny laser cut perforations to boost cooling and aerodynamics. Unlike most races where a runner is adjusting their pace tactically to just stay ahead of the competition, a record attempt means going flat out from the very start.

That means Kerr needed a shoe that could help him maintain an average speed of about sixteen miles per hour for the whole race, completing each lap in about fifty-five seconds. The notion of running slowly, or the notion of changing gears or speeding up, they're going to feel awful in this shoe. This level of performance highlights how access to such bespoke gear remains strictly limited to a privileged few.

It is just not designed to do that,' says Mr Orr. He explains the gear is truly a weapon built for him to blast through four laps at high speed with a rapid cadence. The last piece of technology involved comes from the speed suit Kerr wore during the race. Brooks noted it was crafted to boost aerodynamics and breathability, featuring laser-cut perforations that release heat and humidity while keeping mobility intact.

Dr Barney Wainwright, an expert on sports performance from Leeds Beckett University, told the Daily Mail that drag, the force a runner must push against, increases with speed. The longer a person runs fast, the more benefit they gain from small reductions in that drag force. At Kerr's target race speed, roughly 10 per cent of his total energy expenditure goes into overcoming drag forces alone. Experts say Kerr could only extract maximum value from his supershoes because of his above-average size and weight. This allows him to generate more power per stride than most athletes. If this resistance had been reduced by even a few percent through specially designed clothing, his speed would have increased enough to cut his mile time by up to 0.5 second.

However, none of these technological advantages would matter much without Kerr's unique physiology. He is somewhat larger and stronger than the average middle-distance runner. His data from the 2024 European Athletics Championship shows he stands at six feet two inches and weighs around 154lbs (70kg). By comparison, Hicham El Guerrouj stood at just five feet nine inches and weighed only 127lbs (58kg) in his prime. While that means he carries more weight, it also means Kerr can generate more power with every stride than most other runners.

Dr Hanley says how fast an athlete can run depends mostly on the force they apply to the ground during each step. If Josh can apply more force because he is stronger, this gives him a large advantage. Brooks also seems to have designed the spikes to take advantage of this greater strength by making the shoe stiffer than normal. Likewise, experts point out that Kerr has a 'near-perfect' build for running. He also has a large chest and well-trained heart and lungs that enable him to fuel his muscles with oxygen and remove waste gases fast enough to keep operating under extreme stress.

Dr Mark Burnley, a leading expert on sports performance from Loughborough University, told the Daily Mail that physiologically, he needs a very big "aerobic engine," or maximal oxygen uptake, to sustain 26 km/h (16 mph) for just over 222 seconds. He is likely to have a large chest containing an extremely well-trained heart and large lungs. This requires very high rates of ventilation to work effectively. While the lungs cannot be trained themselves, you can train the respiratory muscles so they do not fatigue so quickly.

While supershoes and aerodynamic suits might offer a small advantage, Dr Burnley believes these physiological factors are 'first and foremost' what made Kerr's record-breaking race a possibility. He sums it up by saying his success comes from 'a combination of genes, training and an element of luck'.