Concentric contractions: A concentric contraction is a type of muscle contraction where the length of the muscles shorten while undergoing tension. For example, when you pick up a curl bar and perform a biceps curl, the length of your biceps muscles shorten.
Blood in Baby's Stool. Babies can sometimes have blood in their stool that is caused by food allergies, a small anal tear or fissure, or even a temporary case of lactose intolerance. It might even be a drop of blood that came from a cracked nipple, which the baby then passed through his system.
The ingestion of black licorice, lead, Pepto-Bismol, or blueberries can. all cause black stools or false melena. Stools should be tested for the presence of hidden blood. Some upper GI causes of bloody stools can also cause vomiting blood such as in peptic ulcer disease.