Why do track & field sprinters have such big shoulder muscles?

Question

Why do track & field sprinters have such big shoulder muscles?

Answer 1

Sprinting requires strength, and the athletes do total body work, that along with a very low body fat percentage makes their muscles appear big.

Answer 2

It's not just their shoulders ~ their entire bodies are muscular.

One of the reasons is that sprinting is great for your body. Short-burst exercises involving large muscle groups releases a human growth hormone that helps you build muscle.

Contrast the body of sprinter with the body of a marathon runner. When you do extreme endurance type exercises, your body begins consuming itself, and you actually lose muscle mass.