When you watch footage of the Olympics from back in the 1920s, it's hard to imagine the athletes involved did any training at all. Their physiques are by and large what we would consider average, not the sculpted and toned competitors we know today. But that's because back then the image of the ideal athlete was based on classical human proportions—and average was considered ideal.

We now know that the ideal body type—including size, weight, height, and other factors—varies from sport to sport. And over the years it's resulted in dramatic changes seen in Olympians. The average gymnast, for example, has shrunk from 5'3" to just 4'9" over the past 30 years. So if you tower over your classmates and have dreams of Olympic gymnastic gold, it might be a good idea to focus on your studies instead.