BoniR,
I wouldn't overthink it. Unless you are in the tiny minority that has continuing side effects from the nal after the first couple of weeks, I bet taking nal and running won't be a problem. Just take the nal in the evening and run in the morning if possible? It is true that it takes UP TO 24 hours for a 50mg pill to be out of your system, but I've had no problem taking nal on, say, a wednesday night, and working out on Thursday in the day. Obviously, for a race, you might want to not drink the night before anyways so that solves that

EL