Langer Name Meaning. German, Dutch, Danish, and Jewish (Ashkenazic): nickname for a tall man, from an inflected form of Lang. According to Gottschald, in the Franconian dialect of German this was also a term for an unskilled laborer (more fully, Handlanger).
Muscle does not weigh more than fat, any more than lead weighs more than feathers. A pound is a pound is a pound. Where the misunderstanding often comes in is that muscle is much more dense than fat, so that, by volume, it seems to weigh more. That is, a pound of muscle occupies less space than a pound of fat. In addition, because a pound of muscle burns more fat than a pound of fat, even at rest, by increasing your lean muscle tissue mass, you're helping your body burn more calories. But back to your question.
When you exercise and isolate a muscle group, lactic acid, produced naturally by your body, begins to build around that muscle. As the lactic acid surround the muscle, it results in a burning sensation. While the burn is often associated with becoming stronger, the feeling of heat and fatigue often ends your workout. After a certain number of repetitions, the lactic acid causes muscle fatigue as it interacts in the calcium in your body.