Drafting or slipstreaming is an aerodynamic technique where two vehicles or other moving objects are caused to align in a close group, reducing the overall effect of drag due to exploiting the lead object's slipstream. Especially when high speeds are involved, as in motor racing and cycling, drafting can significantly reduce the paceline's average energy expenditure required to maintain a certain speed and can also slightly reduce the energy expenditure of the lead vehicle or object. Drafting in sport Drafting is used to reduce wind resistance and is seen most commonly in bicycle racing, motorcycle racing, car racing, and speedskating, though drafting is occasionally used even in cross-country skiing, downhill skateboarding, and running. Some forms of triathlon allow drafting. Drafting occurs in swimming as well: both in open-water races (occurring in natural bodies of water) and in traditional races in competition pools. In a competition pool a swimmer may hug the lane line that separates them from the swimmer they are abaft of thereby taking advantage of the liquid slipstream in the other swimmer's wake. Drafting also occurs in competitive longboarding. It is believed, but not yet conclusively proven, that thoroughbred racing horses draft each other, especially in longer races. Cycling In cycling, any time one bicyclist is riding behind another, energy is conserved, especially at higher speeds. In road bicycle racing, the main (largest) group of tightly packed cyclists in a race is called a peloton where cyclists ride in a long formation with each (but not the first rider) drafting behind the others before them. When cyclists ride fast they form a paceline. Each cyclist, except the first, is drafting behind another one. In order to ride very fast, a team of some skilled cyclists may form the "Belgian tourniquet". Successively, each cyclist leads the group. Drafting can be cooperative: several competitors take turns in the lead position (which requires the most effort and energy consumption). It can also be competitive or tactical: one competitor will try to stay closely behind another, leaving the follower with more energy for a break-away push to the finish line. Running Drafting behind another runner can conserve energy, although the effect is less than in cycling due to the fact that speeds are lower. Nike worked with the aerodynamics expert Robby Ketchell at the University of New Hampshire to experiment with and select a formation of pacemakers that would best minimize drag