More than any other event in professional rodeo, tie-down roping has roots dating back to the working ranches of the Old West. When calves were sick or injured, cowboys had to rope and immobilize them quickly for veterinary treatment. Ranch hands prided themselves on how quickly they could rope and tie calves, and they soon turned their work into informal contests. As the sport matured, being a good horseman and a fast sprinter became as important to the competitive tie-down roper as being quick and accurate with a lasso. In today's modern rodeo, the mounted cowboy starts from a box, a three-sided, fenced area adjacent to the chute holding the calf. The fourth side of the box opens into the arena. The calf gets a head start determined by the length of the arena. The calf gets a head start determined by the length of the arena. One end of a breakaway rope barrier is looped around the calf's neck and stretched across the open end of the box. When the calf reaches its advantage point, the barrier is released. If the roper breaks the barrier before the calf reaches its head start, the cowboy is assessed a 10-second penalty. When the cowboy throws his loop and catches the calf, the horse is trained to come to a stop. After roping the calf, the cowboy dismounts, sprints to his catch and throws it by hand, a maneuver called flanking. If the calf is not standing when the cowboy reaches it, he must allow the calf to get back on its feet, then flank it. After the calf is flanked, the roper ties any three legs together with a pigging string - a short, looped rope he carries in his teeth during the run. While the contestant is accomplishing all of that, his horse must pull back hard enough to eliminate any slack in the rope, but not so hard as to drag the calf. When the roper finishes tying the calf, he throws his hands in the air as a signal that the run is completed. The roper then mounts his horse, rides forward to create slack in the rope, then waits six seconds to see if the calf remains tied. If the calf kicks free, the roper receives no time.