When Eliud Kipchoge broke the 2-hour marathon barrier, nothing was left to chance.
The Kenyan athlete, 34 at the time, had 42 of the world’s best runners to pace make, a pancake flat course in Vienna, Austria, hydration delivered by cyclists. He even wore special carbon fibre soled Nike shoe, called the Vaporfly Next%, which the manufacturer claimed increased running economy by 4%.
But despite the marketing hype, his shoes were probably not the decisive factor in his time of 1:59:40.2.
Arguably, the phalanx of runners, tightly bunched in an arrow formation around him to scythe through the wind, made the biggest contribution to his astonishing physical accomplishment.
In other words, drafting was the big advantage.
Is Wind Resistance a big Deal in Running?
In cycling, drafting is widely implemented in order to improve aerodynamics, with wind resistance accounting for 80 to 90% of the cost of cycling (Kyle, 1978).
Although in comparison wind resistance only accounts for 4 to 8% of the metabolic cost of running, it is a factor that can be potentially improved with no training.
Even when there is no wind resistance, elite marathon runners are travelling so fast that air resistance slows them down.
Drafting in running has been shown to decrease energy consumption by 2 to 4% when running at a middle and long distance speeds, in addition to increasing running speed by ~0.1 m·s-1 (Kyle, 1978).
How Much Energy Does Pushing Air Take?
The energy cost for a marathon runner to overcome air resistance on calm day was 2%, running at a speed for 5 m·s-1 equating to a ~2:20:39 marathon time, according to a study by Davies (1980).
When the running speed was increased to 6 m·s-1 (~1:57:10) the energy cost increased to 4%.
Pugh (1971) calculated that drafting one metre behind another runner running at 4:30 min·mile-1 pace saves around 80% of the energy that would otherwise be required to combat air resistance, equating to running one second faster per 400 metres.
How Close Should I Run
The optimal distance behind from the runner in front when drafting is between 40 to 80 cm. This takes a bit of practice to get comfortable running this close to the person in front.
It’s also important to assess constantly which way the wind is coming and adjust accordingly. A strong head to cross wind will mean you’ll have to shift behind the front-runner. In cycling, this causes an echelon across the road as riders scramble for shelter.
Don’t Leave Anything to Chance
When every second counts and we’re at our limits, saving as much energy as possible could make a huge difference in race result or eventual time.
Pro cyclists learned this lesson decades ago. Baggy jerseys gave way to super tight skin suits. Round tubes on bike frames are now wind tunnel sculpted teardrops.
Runners could learn from this too. We could start by ditching baggy shorts and flappy tops.
Next time you set foot on a start line, don’t leave anything to chance. Remember you’re not just battling the clock and fellow competitors, you’re also up against an invisible force of nature: the wind.
