If you look at sprinters compared to swimmers, I would say the sprinters are much more built. If you compare marathon runners to swimmers, it is the swimmer that is more built.

This brings up the interesting topic of anaerobic vs. aerobic exercise which running can be either. Typically one would think of anaerobic exercise as lifting weight or strength training, but sprinting is also anaerobic, meaning you are building muscles.

When you run at a slower pace you are conditioning your lungs and not your muscles as much. This is aerobic exercise, and why marathon runners are so skinny because they are more focus on lung capacity than muscle building.

When you sprint your muscles are actually being broken down and then when you stop they get rebuilt as stronger and larger muscles. This is the reason no one can sprint a marathon.

What is curious to me is that elite marathon runners "jog" at what I would consider being a sprint for myself. So, I wonder if sprinting would be an anaerobic or aerobic exercise for myself?