The Sub Two Hour Marathon: Eliud Kipchoge and Human Endurance

What Kipchoge did in Vienna

The INEOS 1:59 Challenge took place in Vienna on 12 October 2019. The event was specifically designed to attempt a sub 2 hour marathon. Multiple optimisation strategies were combined including pacemaking, course selection, footwear and timing. Kipchoge completed the distance in 1:59:40.

The athlete

Eliud Kipchoge was born in 1984 in Kapsisiywa, Kenya. He won the 5000 metres at the World Championships in 2003 before transitioning to marathon racing. He has won 16 of his 19 marathon starts including the Olympic marathon in 2016 and 2020 and multiple London, Berlin and Chicago marathons. He set the official marathon world record at 2:01:09 in Berlin in 2022.

The course

The INEOS 1:59 Challenge ran on the Prater Hauptallee in Vienna, a flat tree lined avenue measured for the attempt. The straight sections minimised cornering losses. Temperature on the day was approximately 8 degrees C with low humidity, considered near ideal for marathon performance. The course met the geographical and elevation requirements for record consideration but the pacemaking arrangement did not.

The pacemaking

Kipchoge ran behind a formation of 41 elite pacemakers rotating through the race. The pacemakers ran in a V formation directly in front of Kipchoge providing aerodynamic drafting. The arrangement reduced air resistance significantly. Standard record marathon attempts have pacemakers but not in rotating formation. This is one reason the IAAF did not recognise the time as an official record.

The 1:59:40 split

Kipchoge passed halfway in 59:35 and the full distance in 1:59:40. The pace held remarkably consistent across the entire distance. Most marathon attempts at this level show some slowing in the final 10 km. Kipchoges pace remained within seconds of target across all splits. The pacing discipline was as remarkable as the absolute time itself.

What sub 2 hour marathon performance requires

Running a marathon in under 2 hours requires specific physiological characteristics combined with ideal conditions and optimised equipment. Each component contributes to making the time possible.

VO2 max

Elite male marathon runners have VO2 max values typically between 75 and 85 ml/kg/min. Kipchoge reportedly tests at the upper end of this range. The aerobic capacity is necessary but not sufficient. Several runners with comparable VO2 max have not approached the sub 2 hour threshold. Aerobic capacity is one input among several.

Lactate threshold and running economy

Lactate threshold determines the pace that can be sustained without crossing into anaerobic territory. Running economy describes the oxygen cost of running at given pace. Kipchoge has exceptional values in both. His threshold pace is below 2 hour marathon pace. His running economy is among the lowest measured oxygen costs per kilometre. The combination produces sustainable pace at sub 2 hour levels.

Energy substrate use

A sub 2 hour marathon expends approximately 2500 to 3000 kcal. Most of this comes from carbohydrate (glycogen) at the high intensity sustained. Elite runners can take in 60 to 90 grams of carbohydrate per hour during racing. The total intake during the 2 hour race approaches 200 grams of carbohydrate, partly offsetting the demand. Kipchoge consumed carbohydrate drinks at multiple points across the Vienna attempt.

Body composition

Kipchoge weighs approximately 52 kg at 1.67 metres tall, giving a very low body mass index of approximately 18.6. Body fat percentage is at the lower limit of healthy range for an elite runner. The combination of small mass with high absolute aerobic capacity produces the exceptional running economy that supports sub 2 hour pace.

What made the Vienna time possible

The Vienna time was approximately 2 minutes faster than the official world record at the time. The difference came from optimisation across multiple variables that ordinary marathon racing does not allow.

The pacemaker formation

The V formation of pacemakers directly in front of Kipchoge produced significant aerodynamic drafting. Estimates suggested the drafting saved approximately 30 to 60 seconds across the marathon distance. Standard marathon racing has pacemakers but not in rotating optimised drafting formations. This was one of the most contested aspects of the record verification question.

The Nike Vaporfly shoes

Kipchoge wore prototype Nike Vaporfly shoes for the Vienna attempt. The shoes contain a carbon fibre plate and high stack of compliant foam. Research has shown the shoes improve running economy by 2 to 4 percent compared to previous racing shoes. This translates to approximately 1 to 2 minutes across marathon distance for elite runners. World Athletics subsequently regulated shoe specifications partly in response to performance gains from carbon plate shoes.

The conditions

Weather on the day was approximately 8 degrees C with low humidity. Marathon performance is sensitive to temperature. Optimal temperatures for elite marathon performance sit in the 5 to 12 degree C range. Times worsen significantly above 15 degrees C. The Vienna conditions were near optimal. Major city marathons accept whatever conditions occur on race day.

The hydration delivery

Kipchoge received drinks from cycling supporters at multiple points across the course. The bottles were handed directly to him without slowing pace. Standard marathon racing requires runners to collect drinks from tables at designated water stops. The delivery method in Vienna allowed faster hydration without the slight pace disruption of standard collection.

Lessons from sub 2

The Vienna performance demonstrated that human physiology can support marathon performance below 2 hours under optimised conditions. The lessons inform thinking about training, equipment and the gap between official records and absolute capability.

The 2 hour barrier was not absolute

Many sports scientists had predicted the sub 2 hour marathon would not be achieved for decades. The Vienna time showed the barrier was closer than commonly assumed. The official record at 2:01:09 sits within reach of a sub 2 hour run in standard race conditions over coming years. Performance barriers in endurance often fall faster than predictions suggest.

Equipment matters significantly

Carbon plate running shoes have transformed marathon racing since 2017. Course records at most major marathons have fallen multiple times since the shoes became widely available. World Athletics has regulated shoe specifications to limit further gains. For ordinary marathon runners the implication is that current generation racing shoes do produce measurable performance benefit, though not at the magnitudes seen at elite level.

Pacing discipline is decisive

Kipchoges pacing across the Vienna marathon was within seconds of target across all splits. This is one of the most studied aspects of his performance. Even pacing tends to produce better marathon outcomes than positive splits (faster start, slower finish). The principle applies at all marathon performance levels. Most amateur marathoners would benefit from more conservative early pacing.

Single performances do not generalise

The Vienna conditions were optimised across multiple variables. Reproducing the time in standard marathon racing remains difficult. Kipchoge himself has run multiple marathons since at slower times under standard conditions. The achievement demonstrates the physiological possibility but does not predict typical marathon performance. Marathon racing is sensitive to many variables including weather, course and tactics.

More from the limits library

For another elite marathon case, our Running on Minimal Body Fat guide covers Haile Gebrselassie. Breaking the Ironman Barrier covers Jan Frodeno. And Training at Extreme Altitude covers high altitude training similar to Kipchoges Kenyan base.