Even in a friendly marathon, they do announce the person with the fastest time so it's sort of a competition even if you're mostly competing against yourself. It's certainly a sport in the Olympics and in other track and field competitions.So what’s a marathon?
Not in the U.K. We talk about sponsored walks or sponsored runs.A "walkathon" is a charity event. It raises money (donations) for the charity. It is not a competition. People do not try to get there first. A walkathon has has a planned route -- for example, 5 km long. The goal is for everyone to walk all 5 km.
Each person that walks this route has gotten friends to pledge money. Basically each friend agrees "If you walk 5 km, I will pay $20 to the charity". So if you get 5 friends to agree, and then you walk the 5 km walkathon, the charity gets $100. If 20 people each do this, the charity gets $2,000.
Except for skiing, fishing, hunting, skydiving, etc.No, walking isn't a sport. A "sport" is a competition.