A sub-2-hour marathon: what will it take and what can we learn?

Andrew Hamilton looks at the science of running a sub2-hour marathon. Is it possible, what training regimes will bring it about and what lessons can sub-elite runners learn?

On a lonely Italian running track in May 2017, the running shoe manufacturer Nike helped a group of elite African runners to attempt to run a sub-2-hour marathon. As well as assembling a group of world-class runners (two of whom acted as pacers) and running the distance on a perfectly flat surface in calm and cool conditions, Nike had another ace up its sleeve. The runners were shod with Nike’s latest hi-tech running shoe - dubbed the Zoom VaporFly Elite (see image above). Not only was this shoe superlight, it also included the best energy-returning materials that Nike’s scientists could provide, along with a carbon-fibre plate designed to further reduce energy return⁽¹⁾. In the end, the Kenyan runner Kipchoge (pictured in the centre) fell just short of the mark wearing the trainers. But his finishing time of two hours and 25 seconds was almost three minutes faster than the official world record of 2:02:57, set by Dennis Kimetto in Berlin in 2014.

Is it possible?

Although the conditions for Nike’s attempt at a sub-2-hour marathon were rather artificial, the mere fact that Kipchoge fell just 25 seconds short of breaking the 2-hour barrier raised eyebrows among some members of the sports science community, suggesting that the reality of a sub-2-hour marathon is a matter of ‘when’, not ‘if’. However, not all sports scientists are convinced that two hours is breakable; some even believe that a sub-2-hour marathon is a physiological impossibility⁽²⁾ while others believe it will happen – and happen quite soon^(3,4).

To understand why there’s much debate over this issue, it’s useful to look at the progression of marathon records over time. These are shown for men and women in figures 1A and 1B respectively. In both of these graphs (but particularly for the women), we can see how the marathon world record drops over time. However, we can also see that the curve has an exponential decay character to it; as time progresses, the reduction in times become ever smaller, never quite seeming to approach the magic 2-hour mark. Also, as time passes and training/nutrition becomes ever better among more athletes, the degree of variability among athletes (represented by how far under the plot of the curve each world record was) also seems to reduce.

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Figures 1A and 1B: The progression of world record marathon times for men (top) and women (below)

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Together, the above would suggest that breaking the 2-hour barrier might be nigh on impossible after all. But take another look at the plots and you can see that there are instances in recent times when sudden, unexpectedly large improvements are made – even in recent times. In figure 1A, the Nike-inspired attempt (red arrow) on the record produced a huge drop in times compared to incremental drops beforehand. In figure 1B, we can see that Paula Radcliffe’s 2003 marathon world record (still unbeaten to this day) represented a huge reduction in time compared to what had gone before. This has led a number of sports scientists to speculate that with extra research-inspired improvements in training and nutrition, a step change improvement in the world record time is very possible, and (in the case of men) enough to break the 2-hour barrier.

What’s needed to break the 2-hour barrier?

While they undoubtedly help, high tech shoes are probably not sufficient in themselves to allow the world’s best marathoners to break the 2-hour barrier. Yes, shoes like the Nike Zoom Vaporfly do offer tremendous energy-return characteristics to reduce the energy cost per mile of running. For example, according to a study done for Runner’s World by Biomechanica, a research lab in Portland, Oregon, the best commercially available midsole materials in shoes return up to 70 percent of the energy of impact⁽⁵⁾. Trying to improve this is part of what Nike was attempting. However, the Biomechanica study also found that the difference between the best energy-returning shoes and more average ones was only about one percent of the total amount of the overall energy involved in running – significant but not sufficient.

Predicting the future

If technology can only get a world-class runner trying to break the 2-hour barrier so far, where will the other performance gains need to come from and which of these factors will be most important? In a fascinating new study published by a group of international scientists from Brazil, Switzerland and Greece, researchers have sought to try and answer these questions⁽⁶⁾. In particular, this study has summarised the key factors that have been argued as important in improving a marathon performance, and then performed a mathematical analysis to predict when the first sub-2-hour marathon would be run by a male runner. The study also attempts to quantify which aspects of endurance performance are most likely holding back a sub 2-hour time (ie those which most need improving) and also which factors most likely explain the difference in marathon-running performances between men and women.

To do this, the researchers collated the best official marathon race times from males and females. This included data from the 1999–2018 (up to April 2018) World Championships and the Olympics (the best official Olympic Marathon race times since 1920 for males and 1984 for females, which was the year when the marathon running distance was standardised and involved females, respectively).They also included the times of the fastest marathons run in a given year for both males and females.

These times were then subject to a ‘regression analysis’, which is a mathematical technique to model a set of points lying on a curve from data already collected (figures 1A and 1B) and to predict where the curve is heading – in this case, how long it should take to hit the 2-hour time barrier. The equation that best fitted the data was as follows:

Y =0.045X²–15.12X +3194

This yielded a predicted date of 2027 for the first sub-2-hour marathon.

When the Kipchoge’s 2017 record using Nike’s Zoom VaporFly Elite shoes was included, the regression equation was slightly different:

Y =0.0417X²–14.18X +3128

This equation yielded a predicted date of 2026.

The findings of this analysis are not too far away from those of some other studies. Remarkably, Joyner and his colleagues analysed male’s marathon world records back in 1985 and predicted that the first sub-2-hour marathon would be run 2020–2022⁽⁷⁾. Although this was based on a linear (as opposed to a curvilinear) interpretation of year-on-year improvements of 10–20 seconds, this prediction is in close agreement with the study above. However, other researchers are in disagreement. A 2016 study based on running velocities predicted that the 2-hour record will not be broken this century⁽⁸⁾. However, given Kipchoge was just 25 seconds away from the 2-hour barrier last year, you’d have to be brave to bet that the 2-hour record will still be intact come 2100!

Biomechanical factors

The biomechanical and environmental effects that could affect human performance in marathon running have been widely discussed in a review by Hoogkamer and his colleagues published last year⁽⁹⁾. In this study, the researchers explained that a sub-2-hour marathon requires an average velocity of 5.86m/s. This velocity is 2.5% faster than the current official world record velocity of 5.72m/s, which produced a time of 2:02:57 (Dennis Kimetto in the 2014 Berlin Marathon).

They went onto calculate how much time could be saved by taking advantage of unconventional drafting strategies, a consistent tailwind, a downhill course, and specific running shoe design features while staying within the current International Association of Athletic Federations regulations for record purposes. They concluded that running in shoes that are 100 grams lighter, along with second-half scenarios of four runners alternately leading and drafting, or a tailwind of 6.0m/s, all combined with a 42-metre elevation drop from course start to finish could result in a time well below the 2-hour marathon barrier.

The problem however is that downhill courses and cooperative strategies with fresh runners to overcome the air resistance are not allowed by the International Association of Athletics Federations (IAAF). Moreover, the Nike Breaking2 attempt performed by Kipchoge had the best conditions possible in a non-downhill course, but the best marathon performance of all time still was not enough to beat the sub-2-hour barrier. This suggests further training improvements will be required.

The perfect formula

In their recently published paper predicting a 2026/2027 sub-2-hour marathon⁽⁶⁾, the researchers from Brazil, Switzerland and Greece also looked the key physiological factors that will need to be optimised to break this barrier. Pooling research from a  number of previous studies, they concluded that the first sub-2-hour marathon runner will need to have not only a superbly high aerobic capacity (VO2max), but the ability to sustain a high percentage of that VO2max (ie a superb anaerobic threshold [LT] too).

In addition, our heroic runner will need to have very high levels of running economy. Running economy measures how efficiently a runner can cover distance in terms of oxygen consumption. High running economy means less oxygen is consumed per mile per kilo of body weight, and in recent years, research has confirmed that very high levels of economy go a long way to explaining the performance of the world’s best runners⁽¹⁰⁾. The researchers also considered other characteristics that would be favourable to a sub-2-hour marathon including genetic makeup and tactical approach. They then summarised these factors in a graphic, which is shown in figure 2.

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Figure 2: Speculative estimates of the relative importance of fundamental factors affecting marathon performance in elite runners⁽⁶⁾

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You can see that in terms of genetics, there’s a strong likelihood that the first sub-2-hour marathoner will be of East African descent, while tactics, physiological characteristics and biomechanical factors (such as shoes, running style) will also be key to success. In terms of tactics, the use of drafting and maintaining an even pace are likely to be equally important during the race. Physiologically, excellent running economy is considered to be even more important than high VO2max and lactate threshold (LT), although these are still extremely important! Biomechanically, low weight and good forward propulsive strength will be vital. Ventilatory efficiency will also be important with good technique such as balance and leg swing also required.

Lessons for mere mortals

Speculating what and how long it will take to break the 2-hour barrier for the marathon is fascinating in itself. But there are also lessons here for less elite runners looking to improve their own marathon performances. You can’t alter your genetic makeup but you can work on tactics, physiological fitness and on improving your biomechanics.

In particular, research suggests that developing your running economy and lactate threshold seems particularly worthwhile. For the former, this means not only getting sufficient ‘miles in the bank’, but also performing lower-body strength and conditioning exercises, which are known to improve economy. These might include squats, lunges, leg presses and plyometrics exercises. In terms of tactics, ensuring an efficient pacing strategy seems essential. Biomechanically meanwhile, there’s evidence that ventilatory efficiency is also worth working – for example using inspiratory muscle training (IMT) devices such as ‘PowerBreathe’ and ‘Threshold’. You can find links to articles on all these topics below.

Andrew Hamilton, Sports Performance Bulletin editor

References

1. Adam Elder. Nike Unveils Shoes Designed to Run a Sub-2-Hour Marathon. Competitor, March 7, 2017
2. Meas Phys Educ Exerc Sci. 1998;2(4):205–223
3. Sports Med. 2017;47(9):1739–1750
4. J Appl Physiol. 2011;110(1):292–294
5. Jonathan Beverley, “The Truth About Energy return in Your Shoes,” Runner’s World (online), October 15, 2015
6. Open Access J Sports Med. 2018; 9: 139–145
7. J Appl Physiol (1985). 2011 Jan; 110(1):275-7
8. Eur J Sport Sci. 2016; 16(4):393-401
9. Sports Med. 2017;47(9):1739–1750
10. Appl Physiol Nutr Metab. 2006 Oct; 31(5):530-40