You can now get some seriously complicated running machines. Some of these have screens to simulate the effects of many virtual competitors.
Today’s invention is an addition to one of these which consists of a high powered fan with variable air temperature.
This is powerful enough to simulate the effects of drag and windchill on an athlete, without the need for a fullscale wind tunnel.
It could also be used to train athletes in connection with tactics -such as ‘drafting’ runner(s) ahead before pulling out to overtake (or by sucking, the influence of a strong tailwind).
A more advanced version would be a treadmill with powered wheels so that a group of these machines could change their relative positions to model the way runners contend for track space in a real race.