Fun question! It takes two people to participate in a three-legged race. The participants stand shoulder-to-shoulder facing the finish line. They use a rope, rubberband, string, or whatever is needed to tie their inner legs together. For instance, the person on the right side ties his or her left leg to the right leg of the person on the left side. Usually, the legs are tied together at the ankle, in a sense, creating three legs to be used for running the race.
The first couple to reach the finish line wins the race.
I hope this helps.