What was the corruptible crown the Olympic athletes ran for?
The corruptible crown was merely a wreath of leaves, not a lasting prize. By the time the athletes returned home, it had dried up and was good for nothing. Paul contrasts that perishable reward with the incorruptible crown believers pursue, which never ends.
Les explains that Paul is alluding to the Olympic athletes in I Corinthians 9. These athletes trained and trained with temperateness, not destroying their bodies through overtraining or arriving flabby and unprepared. They competed to obtain a corruptible crown, which was just a wreath of leaves. By the time they got home, it was dried up and good for nothing, perhaps put between bookshelves. Paul uses this to tell believers to run likewise, not for salvation but for the prize, an incorruptible crown that will never end.
And every man that striveth for the mastery is temperate in all things. Now they do it to obtain a corruptible crown; but we an incorruptible.