Bengaluru, Sept. 21 -- Thousands of athletes have arrived at the Aichi-Nagoya Asian Games chasing the smallest of margins: a little more speed, a fraction of a second.

An 800m race is over in less than two minutes. Medals and records can turn on milliseconds. Elite athletes train hard, perfect their stride, count their steps, refine their shoes - and, eventually, start worrying about the air.

This week in London, Keely Hodgkinson turned up looking like a sci-fi character. Her one-off Nike speed suit was black, hooded and full-length, running from head to ankle, with an open back and even a hole designed around her ponytail. Across the hood, shoulders, torso and thighs sat tiny 3D-printed structures called vortex generators. Their purpos...