We are highlighting the main findings of a recent article that has examined the drafting strategy of Kenenisa Bekele in the Berlin 2019 marathon, where he run the second fastest marathon time ever in 2.01.41. Using a simulation model his drafting positions behind the pacers were studied, and how they affected his drag resistance and aerodynamic power.
Drafting has been widely used in sports, at least until the Covid-19 outbreak. Using a “sheltered” position athletes try to get an advantage from going behind one or several pace-setters.
This strategy was key in the heavily publicised Ineos 1:59 challenge, that got Eliud Kipchoge under the 2 hours barrier in Vienna last October. In Kipchoge´s successful, although unrecognised attempt, five pacers formed an inverted arrowhead in front of him, with two additional runners behind.
As for Bekele he used 3 pacers for the first 25 kilometres (not so many runners in the world would have been capable of keeping his pace for longer). His splits were 1.01.05 for the first half and 1.00.36 for the second. They were positioned side-by-side along a frontal axis. Bekele did not maintain a fixed position behind this pacers’ line. Three positions were identified and compared using a computational model with Bekele running alone.
Therefore, the article compared among four conditions (see first figure accompanying the post):
- Bekele running alone
- Bekele behind one of the lateral pacers
- Bekele between two pacers
- Bekele behind the central pacer
Briefly, the study showed (see second figure) that Bekele benefited from using pacers. Running alone Bekele had to “fight” against an aerodynamic power of 44 watts. Meanwhile running accompanied the aerodynamic power ranged between 27 and 19 watts. This decrease in “force opposition” could result in an aerodynamic power gain of 57%.
The best aerodynamic, offering the maximum reduction of air resistance, was achieved when Bekele run just behind the central pacer (d), although it was very similar to running between the two lead runners (c).
These aerodynamic improvements lead to a maximum gain of only 2.84% on the total mechanical power. Although air resistance is key in the power output of sports such as cycling (80–90%), its impact is considerably lower in running.
Despite the limitations of the study, simplified in terms of runner anthropometric differences, body kinetics and other external factors (weather conditions, running shoes, course, etc) this relatively small improvement in aerodynamics may hold the key in breaking the world marathon record in a future attempt.
Bibliography:
Numerical Investigation of the Impact of Kenenisa Bekele’s Cooperative Drafting Strategy on Its Running Power During the 2019 Berlin Marathon
Polidori G, Legrand F, Bogard F, Madaci F, Beaumont F
J Biomech. 2020 Jun 23; 107:109854. doi: 10.1016/j.jbiomech.2020.109854.
