Inline aerodynamic drafting optimization in long-distance running: the effects of pacer body size on drag and performance.

This study investigated the influence of pacer body size on the aerodynamic drag experienced by elite marathon runners. Using 3D numerical simulations, various drafting configurations were analyzed at a running speed of 21  km/h with 1.2 m spacings between runners. The modeled runner groups comprised one elite protected marathoner (1.80 m) and one or two pacers of different heights (1.70  m, 1.80  m, and 1.90  m). Isosurfaces of total pressure and pressure coefficient maps revealed that taller pacers generate a wider wake and a more favorable pressure field for downstream runners. Specifically, compared to running solo, a 1.80 m runner positioned between two 1.90  m pacers benefits from a maximum drag reduction of 61.6%, resulting in a 6.48% improvement in running economy and a time gain of 5 min 02 s over the marathon distance. The relationship between projected frontal area, group configuration, and pressure field variations underscores the critical role of fluid-structure interactions on running performance. This study demonstrates that drag reduction depends not only on positioning but also on runner morphology, and opens promising avenues for fine-tuning drafting strategies in elite pack running.