Muscle is an attribute in Omerta City of Gangsters
Muscle helps characters move a longer distance and perform better with melee weapons. Performing better with melee weapons has nothing to do with damage, but just accuracy. Someone with 5 muscle and no perks does 10-20 punch damage at a 60% hit rate and someone with 9 muscle does 10-20 punch damage at a 78% hit rate.
Max MP = Muscle + 5
Melee (damage) = Muscle * 2