The Greeks had two great athletic festivals. One of them you are all familiar with. Its is the … (Let them answer). Right! The Olympic games. The second great athletic festival was called the Isthmian games. The Isthmian games were held at Corinth, so the people Paul was writing to were very familiar with the games.
In order to enter the games, contestants had to provide proof that they had trained rigorously for a minimum 10 months before the games. The last month of training they did in Corinth, where they were involved in supervised daily workouts.
From Gene Gregory’s Sermon: Striving to Win