Mosher's calf 

Mosher's calf describes the physical pain that can develop in the gastrocnemius muscle at the hind part of the leg due to over exertion during prolonged periods within a mosh pit. Causes of the condition include; awkward landing after an intense jump and fist pump move, as well as bodily injuries incurred from remaining in tight proximity to a large crowd of intoxicated humans with limited control of their own limbs.

"I will have to recover from my mosher's calf before I lock in Falls, but it's a possibility." Sam

Mosher's calf by piphere September 29, 2013