Pugh 1971, wind resistance and drafting in running

Classic Journal of Physiology wind-tunnel and track study of the energy cost of overcoming air resistance in running and walking. Air resistance accounted for about 7.5% of total energy cost at middle-distance speed and about 13% at sprint speed. Running roughly one metre behind another runner virtually eliminated air resistance and cut oxygen uptake by about 6.5% at middle-distance speed, the direct measurement behind the tactical value of drafting. The oxygen cost of running or walking into a headwind rose as the square of wind velocity, so headwinds are punished disproportionately. Foundational and directly measured, but based on a single elite subject, so a landmark measurement rather than a large sample.