Running has seen an uptick in popularity in many parts of the world over the past few decades. To someone in the 1950s or 1960s, it would have seemed strange to see people running all over the neighborhood for no apparent reason. Beginning in the 1970s in the US, a boom in popularity was triggered by such popular runners as Steve Prefontaine. Today, it is one of the most popular outdoor activities. 5Ks, 10Ks, half marathons and marathons are among the most popular events.
Running marathons requires long periods (up to a few hours) of steady, level intensity activity. This activity results in a lot of the body mass being reduced, including muscle and fat.
On the other hand, sprinting is an activity in which the human body is subjected to short bursts of high intensity activity. One can imagine our cave dwelling ancestors on their hunting expeditions doing such fast bursts of activity on going in for the kill. After such a burst, muscle growth tends to occur rapidly. In this way, the body reacts in an antifragile way to short bursts of volatility resulting in large upside.
As can be seen above, the bodies of sprinters and marathon runners can turn out in the end to be very different.