In 1968 Wilbur Wood became the first 26 year old to pitch in 86 games in one season.
Hint: The same could be said for 87 and 88 games in a season at the age of 26, but we haven't gotten there yet.
Based on the following two posts, I declare Wilbur Wood as the record breaker for 87 and 88 as well.
89 is next.