You are running a race, and someone wants to have a mid-race chat with you. But you don’t want to have a conversation. What to do?
Since the person who wants to talk to you in a race is probably a stranger, this creates the need to be polite but direct. If someone starts to chat, just to them, “I don’t want to be rude, but I can’t talk while I run.” The likelihood that someone would argue with this—or even continue talking—is is very low.
He or she might still take offense but don’t feel bad. People sometimes have a hard time taking rejection, no matter how nice you are about it. If someone scoffs or huffs, just keep running.