Use it or Lose it: A Graphic Illustration

Here are some AMAZING pictures from a new study of masters level athletes. The top pic is a cross section of the thigh of a 40 year old triathlete. The bottom is a triathlete at 70. The middle is a sedentary 74 year old man.

Notice any differences? I bet these legs look a LOT more similar on the outside.

The whole study is available for free here. Thanks to Alex for pointing this out.