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The World's Hardest Race According to Science

the World's Hardest Race According to Science

A debate has been running for years. Which foot race is the world's hardest? By utilising scientific modelling, we've been able to directly compare each of these races against one another to finally reveal the toughest race in the world once and for all...in theory.

We present our findings from analysing the GPX Data and average high temperatures to gauge the predicted calorie burn from the world's toughest races as identified by Runners' World. The intention of this study is to start a dialogue between people to further discuss their thoughts, feelings and experiences on which race they believe is the toughest in the world.



Elevation Gain

Avg. High Temperature

Energy Expenditure



Avg. High Temperature



The Dragon's Back Race in Wales is the longest race out there. The Moab 240 comes in second, taking runners through some of the most beautiful landscapes you'll ever see, while Wild Horse comes in third, offering a more challenging course across South Wales for those up to the challenge.

Total Distance

  • Dragon's Back Race  multi-day

  • Moab 240  non-stop

  • Wild Horse  non-stop

  • Non-stop Race

  • Multi-day Race


The Tour des Geants is a mountainous French race, whose name translates to “Tours of Giants”. The course has the most elevation gain out of all the races on this list! However, the most challenging race is not always the one with the highest elevation gain. When we look at elevation gain per mile, The Barkley Marathons takes the top spot.

Total Elevation Gain

  • Tour Des Geantsnon-stop

  • Dragon's Back Race  multi-day

  • The Barkley Marathons  non-stop

Elevation gain per mile

  • The Barkley Marathons  non-stop

  • Tour Des Geantsnon-stop

  • Badwater 135  non-stop

  • Non-stop Race

  • Multi-day Race


One of the most prestigious endurance races in the world, Badwater 135 has a reputation for being hot and tedious. There's no denying it when you see it topping our highest average temperature table by a country mile!

Temperature (c)

  • Badwater 135non-stop

  • Marathon Des Sables  multi-day

  • Everest Marathon  non-stop

energy Expenditure

The Tour de Geants may be the biggest total calorie-burner in the world, but when it comes to sheer difficulty and endurance per mile, there's no contest. We can unofficial announce that The Barkely Marathons might just be the hardest foot race out there today. Share this article and let us know your thoughts on social media.

calories per mile

  • The Barkley Marathons  non-stop

  • Tour Des Geantsnon-stop

  • Badwater 135  non-stop

Total calorie Burn

  • Tour Des Geants  non-stop

  • The Dragon's Back  multi-day

  • Moab 240  non-stop

  • Non-stop Race

  • Multi-day Race



For simplicity, this study looked at calorie burn in relation to GPX data only. Major variables, such as humidity and surface type, have been ignored. Although these variables would have a considerable impact on the energy expenditure required to complete the course, the scientific modelling is either too complicated or data sets not available for analysis.


  1. The GPX data* was acquired from the list of the 'hardest races in the world' as defined by Runner's World.
  2. Each race course GPX file was entered into an 'Energy Consumption When Running Calculator' from Light & Matter to acquire the distance, elevation gain and predicted runner's calorie burn. The analysis assumed a runner's weight of 66kg.
  3.  The average high temperature for each race was then acquired from Weather Atlas. 
  4. The average high temperature was then cross referenced against change in calorie expenditure whilst running versus ambient temperature paper by Horiuchi & Fukuoka to discover the factor of change. 
  5. The calorie burn identified by the Energy Consumption When Running Calculator was then multiplied by the temperature factor to theorise the total calorie expenditure.

The Barkley Marathons

It should be noted that as The Barkley Marathons do not allow GPS trackers to be worn during the race so a GPX route map is not readily available for analysis. Because of this, a GPX route map was traced out from a route map published by The Washington Post.

Energy Consumption Calculator

The Estimate Energy Consumption When Running or Walking Calculator analyses GPX data to predicted a runners calorie burn while completing a specified route. The calculator is formulated on the model by B. Crowell described in the paper, From treadmill to trails: predicting performance of runners

B. Crowell analysed 109,000 race results from 2,200 runners participating in more than one race, so that their times could be compared under different conditions. He formulated a model that could predict the energy expenditure expected by a runner running a set distance on a set incline or decline.

Ambient Temperature Factor

The paper, Impact of ambient temperature on energy cost and economical speed during level walking in healthy young males, analysed the calorie expenditure in males at seven speeds from 0.67 to 1.67 m s−1 (4 min per stage) in thermoneutral (23°C), cool (13°C), and hot (33°C) environments. 

These results suggest that an acutely hot environment slowed the Economic Speed by ∼7%, but an acutely cool environment did not affect the oxygen consumption and carbon dioxide output and Economic Speed. Therefore, at higher temperatures, although the body's ability to consume energy does not change, the participant's speed slows, thus taking longer to complete the distance and expending more calories.

About Rokman

Rokman is mental toughness fitness brand and community, created in 2018 by challenge-enthusiast, Terry Rosoman. After overhauling his own health through fitness challenges, he understood the power they have on improving health and wellbeing first-hand and thought that was a message worth sharing.

In a health and fitness industry obsessed with visual aesthetics, quick-fixes and fluffy words of wisdom, Rokman's straight-talking approach is refreshing real and raw, cutting straight to the core of wellbeing with a message of genuine substance and value. 

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