 When the rider pulls all four reins (both pairs) together, the draw reins become slack, transferring tension to the other pair of reins.However, in the sport of polocrosse, draw reins are fobidden with the exception of Market Harborough.Running reins and draw reins are intended for use when the horse is performing an undesired behavior that cannot be corrected with less extreme equipment, and it is best practice to stop use as soon as the desired response is given.