Aerodynamic drag reduction effects of drafting formations with two to four runners

Aerodynamic drafting is a key technique employed to minimize drag forces experienced by trailing athletes. Although Kipchoge's result in the INEOS challenge (01:59:42) was not officially recognized, the extensive drafting formation involving seven pacemakers attracted considerable attention. In regulated competitive settings, however, recruiting pacemakers of comparable caliber is challenging, posing logistical and financial challenges. Therefore, smaller drafting formations consisting of two to four runners may be a more practical alternative, particularly if they have the same or even higher drag reduction. This study focuses on the aerodynamic drag reduction effect of two to four runners using a combination method of wind tunnel tests and computational fluid dynamics simulations. The results showed that in two-person formations, drag was decreased by 67% when the core runner was located directly behind the pacemaker, with optimal results occurring at minimal longitudinal spacing. In three-person formations, drag reduction reached 72% when the core runner was located between the pacemakers directly in front and behind, again benefiting from reduced longitudinal gaps. In a four-person formation, the drag reduction was 89% when the core runner was located directly behind the three pacemakers in a V-shaped formation with close longitudinal spacing. The drag reduction effect of the four-person formation is better than the INEOS formation (63%). This means that in competitive scenarios, a four-person drag formation could improve the performance gain by about 2.2% (162 s) and the metabolic power gain by 3.1%. These results underscore that smaller drafting formations can provide better aerodynamic benefits in long-distance running.