16 Jun 2017

A Two-hour Marathon

Breaking the four minute mile.
Roger Bannister: 3 minutes, 59.4 seconds
In 1954 Roger Bannister electrified the world by breaking the the four-minute mile barrier. This video of the historic run is narrated by Bannister himself: Four minute mile

Many had believed that running a mile in under four minutes was beyond the capability of the human body. Once that psychological barrier had been broken, new records were set steadily. Bannister's record stood for  less than seven weeks, before being broken by Australian John Landy. And six weeks later both men ran under four minutes in the Vancouver Commonwealth Games, in a race known as the "Miracle Mile".

Roger Bannister and John Landy's "Miracle Mile" immortalized in bronze
outside the Pacific National Exhibition in Vancouver

The Two-hour Marathon Challenge

A far more difficult barrier will be broken soon when someone runs the marathon distance (26.2 miles) in under two hours. Bannister was an amateur athlete - a medical student at the time. He trained himself. He was helped in the race by a friend, Chris Brasher, who set the pace for the first two laps. The two-hour marathon attempt is a very different enterprise.

Both Nike and Adidas have already spent years (and undisclosed amounts of money) on projects to reach this goal. A third project was launched two years ago by Yannis Pitsiladis, a professor of sports and exercise science at the University of Brighton in Britain. He has reportedly been trying to raise $30 million to enable a runner to break two hours by 2019.

Running a marathon distance in two hours is an astonishing feat. It requires a pace of under 4 minutes 35 seconds per mile.  The current marathon world record, set by Kenyan Dennis Kimetto at the Berlin Marathon in September 2014, is 2:2:57 (2 hours 2 minutes 57 seconds). While 3 minutes doesn't sound like a long time over 2 hours, it is an improvement of 2.5%, which is quite significant.

Dennis Kimetto in Berlin

Nike's First Attempt

Kipchoge, Tadese and Desisa

Last month, on May 6th, Nike staged a serious attempt to break the barrier. Nike has been working with three chosen athletes: Eliud Kipchoge of Kenya, Zersenay Tadese of Eritrea, and Lelisa Desisa of Ethiopia. The attempt was made at the Monza race car track, near Milan, Italy. The site was chosen for ideal marathon characteristics: flat terrain, calm winds, low temperature. The three star athletes were supported by a team of 30 elite marathon pacers, and a pace car. They were outfitted with Nike's best running shoes, the newly developed Vaporfly 4%.

The result? Eliud Kipchoge ran a time of 2:0:25 - close, though still significantly off the target. For a number of reasons this time isn't recognized as a world record. It wasn't meant as an attempt at a world record, but as a demonstration that it's possible to run a two hour marathon. Desisa dropped off the pace after 30 minutes, eventually finishing with a time of 2:14:10. Tadese started to fall behind at around mile 20, and he finally clocked 2:06:51. If you have an hour or two to spare, you can see a video of the attempt here: Two hour attempt

So Where's the Science?

1. Shoes

Nike has named its new shoes Vaporfly 4% because they claim that the shoes are 4% more efficient than its current best marathon shoes. What's different? The shoes use an extremely lightweight but resilient foam for the sole. And they have a carbon fibre plate inserted into the sole of the shoe. That plate functions a lot like the carbon fibre blade used by amputee "blade runners". The blade flexes with each step, converting kinetic energy into elastic energy, and then releasing it, returning the energy to the motion of the foot. There's ongoing debate about whether this type of technology confers an "unfair advantage" to its user. If it's deemed to do that, it will be illegal in official races.

The spoon-shaped plate is visible in this image of the shoe
Although Nike will soon begin marketing generic versions of the shoe, the three athletes were equipped with customized shoes, designed to match exactly their individual gait.

2. Pacing

It is optimal to run at exactly the same pace throughout the distance. This attempt used a pace car, which travelled at exactly the required speed for a two hour marathon. It used a laser beam to project a line onto the track to show the pacing athletes exactly where they needed to be.

3. Drafting

Wind resistance is a factor in how much energy is needed to run. Studies have shown that at the required speed of 6 meters/second 4% of your energy is needed to overcome wind resistance. Another study found that 'drafting' eliminates almost all of that wind resistance. (Drafting is where a runner runs behind another runner, who thus shelters them from the wind).

(The faster you're moving, the more important wind resistance becomes. It's extremely important for cyclists. At 40 km/hour over 90% of your energy is needed to overcome wind resistance! In my book Faster, Higher, Smarter you can read the story of cyclist Graeme Obree who was brilliant at finding different cycling positions to reduce drag).

For this attempt, the runners were able to draft behind a V-shaped formation of 6 elite runners at all times. There were ten teams of three who took it in turns to shield the runners. Nike used wind tunnel tests to determine the optimal configuration of the pacers.

So Why No 2-hour Marathon time?

It's a reasonable question. The project was looking for a 2.5% improvement over the existing world record time. Nike claims the shoes alone should have given a 4% improvement. The drafting should have given perhaps another 2% (not 4% because in a regular marathon each athlete will normally spend some time drafting behind competitors). Further advantages were available from the even pace; from drinks being delivered by moped instead of needing to be snatched from a table on the way; from the flat terrain.

Is the science wrong? It's certainly possible, perhaps likely, that laboratory tests don't translate accurately to the road. Perhaps the Vaporfly should be Vaporfly 2%, not Vaporfly 4%. But it's also unrealistic to assume that one of the three runners will deliver a world-record performance for the Nike experiment. Obviously the world record is the most extreme performance ever. It's the outlier of thousands of top level marathon attempts.

It's more realistic to re-frame the challenge as looking for an improvement from an average elite performance. Kipchoge's marathon times are the best of the three athletes. His average time has been 2 hours 5 minutes. So the challenge was to get a 4% improvement in his average performance. With that in mind, it's remarkable that Kipchoge was able to get an improvement of 3.5%. It seems certain that ongoing attempts using technology to assist runners will eventually result in the elusive two hour marathon.

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