Leg Muscle Pain. Claudication, derived from a latin word that means "to limp, " is characterized by pain in the leg muscles. It is caused by blockages in leg arteries depriving the blood supply needed for activities like walking. Resting, or stopping, relieves the pain because less oxygen is needed at rest. "intermittent" refers to the timing of pain: "it hurts upon walking but gone upon stopping, like clockwork.".