The surprising strategy behind running the fastest marathon

Date:
Thu, 24 Aug 2023 12:00:00 +0000

Description:
Eliud Kipchoge, at left in a white tank, behind pacers forming an aerodynamic V in 2019. Robert Szaniszlo/NurPhoto/Getty Images Aerodynamics experts disagree over the best shape for reducing drag: Is it a V or a swordfish? The post The surprising strategy behind running the fastest marathon appeared first on Popular Science .

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Eliud Kipchoge, at left in a white tank, behind pacers forming an aerodynamic V in 2019. Robert Szaniszlo/NurPhoto/Getty Images

In 2019, Kenyan long-distance runner Eluid Kipchoge became the first person
to run a marathon in under two hours . This achievement had held an almost mythical statusexisting, as some physiologists projected, at the edge of a human bodys capabilities. But in the years leading up to Kipchoges feat, he and other elite athletes had squeezed their marathon times ever closer. Finally, four years ago, in an unsanctioned event along a flat six-mile loop in Vienna, Kipchoge cruised at record speed, completing 26.2 miles in one hour, 59 minutes, and 40 seconds.

Officially, the two-hour marathon barrier has not been broken, according to World Athletics, the organization that keeps race records . For one, there were no other competitors in Kipchoges event. Plus, he wasnt alone. He ran in a pack with several expert runners, known as pacers or rabbits, creating an aerodynamic shape around him. Wind tunnel tests and computer simulations helped the team finesse the formation: Five pacers positioned in front made a V, like the inverse of a flock of geese, while two additional racers ran slightly behind the marathoner, at his left and right flank. After each loop, the pacers rotated out for a fresh set of legs. With this protection from headwinds, Kipchoge completed the distance more than a minute faster than he ever had.

But as it turns out, there may be an even better drafting formation for running a marathonor so says a team of researchers at cole Centrale in Lyon, France, who recently tested multiple shapes by placing miniature manikins in
a wind tunnel. Theyve proposed an arrangement, somewhat resembling a swordfishs body, that would reduce drag forces by 60 percent on a runner. It would result in marathon times about a minute quicker than the Vienna V, they claim. Using the swordfish shape, it may be possible to run the fastest marathon ever, the study authors write in a paper recently published in the journal Proceedings of the Royal Society: A .

But the scientists who helped develop and verify the buzzed-about 2019 configuration dispute that assertion, citing flaws in the new studys wind tunnel setup and the proportions of the mini model runners used to explore
it. The paper itself shows huge differences between present results and those from previous studies, says Bert Blocken , a professor of civil engineering
at KU Leuven in Belgium, who used computer and wind tunnel simulations to analyze drag reduction in the Vienna race. While the Proceedings paper indicates that a V-shape reduces drag by 50 percent, Blocken says that past work found it was closer to 85 percent.

[Related: How epic wind tunnels on Earth make us better at flying through space ]

The benefits of marathon formations are not in dispute here. Aerodynamics researchers agree that packs offer an advantage to going solo, especially at the pace elite runners travel. The drag force acting on an object is proportional to the objects speed squared, points out Pietro Salizzoni , a professor of fluid mechanics and an author of the new study. In other words, the faster you go, the more extreme headwinds you face. On a leisurely
stroll, these disturbances are essentially undetectable. But at the speed Kipchoge ran at for his recordan average of 4.5-minute miles or 13 miles an hour, which would feel like a sprint to most peoplepushing air out of the way becomes a literal drag. Blocken and his team tested these figures, scanned from marathon runners, in a wind tunnel. KU Leuven

For Vienna, three studies pointed to a V-shaped pack, Blocken says: a UK consultancy companys tests of 110 formations using fluid dynamics
simulations; his teams own computer simulations of 15 formations; and wind tunnel experiments involving 10 formations. (Confidentiality clauses from INEOS, the British chemical company that sponsored Kipchoges race, means
those reports have not been published.) All three detailed previous studies gave the same outcome, Blocken explains: The configuration with a V-shape in front of the target athlete and two runners behind him produced the lowest aerodynamic drag.

Salizzoni and his coauthors independently tested eight formation styles, including the INEOS V-shape, by mounting stationary 6.5-inch manikins in an indoor wind tunnel. Their goal was to measure air resistance proportional to what a marathoner would experience. Ultimately, they also found a benefit to placing two pacers in the back. The force acting on a running target is the sum of the pressure on the front and on behind, Salizzoni notesthose in the rear help minimize any pressure drops. You want to control the wake you are producing, he says, similar to the back wings on a Formula One race car. A
top view showing where pacers would be, in blue, and the target athlete, in red, for three permutations of the swordfish formation. (The measurements are 1/10 scale, in centimeters.) Marro et al. Proc. R. Soc. A

Where the new findings differ substantially is in the positions of the pacers out front. Salizzonis team concluded the most effective was a swordfish-profile shape: a lone pacer, followed by four other pacers forming
a skinny diamond four feet behind, and finally the target athlete less than five feet behind the diamonds rear. The narrower wedge in this formation
could allow runners to sort of slice through the air, University of Colorado Boulder physiologist Rodger Kram, who wasnt part of the research team, told Science News .

[Related: Why do marathon runners get the runs? ]

Blocken remains unconvincedhe argues that the teams manikins were inappropriately proportioned. The model used in the study by the present authors seems to be some sort of small cartoon model that is very different from the geometry of a real human body, he says, referring to the unrealistic chest-belly ratio and sharp edges of the models poseable joints. Blockens studies used smooth and solid manikins based on scans of real human marathoners. A poseable manikin used to test the eight drafting formations. Marro et al. Proc. R. Soc. A

Salizzoni counters that their figurines had a equivalent area and an equivalent form to an athlete, and that using moveable models helped provide more accurate data. After all, humans in motion dont have their arms and legs fixed in place. This could still give a realistic result for the single runner, Blocken say, but he points out that the fluid dynamics of formations are much more sensitive to subtle changes. In fact, as the New Yorker noted
at the time, the configuration for the 2019 race was so precisely tuned that if Kipchoge moved five inches out of place, he would be much more exposed to aerodynamic drag.

It may be some time before a top marathoner puts another pack run to the
test. Kipchoge typically only competes in two marathons a year. His second race of 2023 will be in Berlin in September, where he officially set the
world record in 2022without the help of a formationat 2:01:09.

The post The surprising strategy behind running the fastest marathon appeared first on Popular Science . Articles may contain affiliate links which enable us to share in the revenue of any purchases made.



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Link to news story:
https://www.popsci.com/science/marathon-running-formations/


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