He measured his calves after his first week of training. The right leg was 40.3 cm, and the left was 40.5 cm. "If I can get my calves to 41 to 41.5 cm by the end of this challenge, I will be super ...

Four months after his injury, Matt's calves are looking strong again. "I'm pretty happy," he says. "Bear in mind, I haven't been training specifically to build mass, it's more like rehab-style ...

Particularly those awful calf ones ... a lack of strength training. Researchers signed up 84 marathoners who agreed to undergo a series of tests before and after their race.