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.
Other more serious causes of blood in stool include: 1  Crohnâs disease â Crohnâs disease causes inflammation of the digestive tract lining and can lead to severe diarrhea and abdominal pain. 2  Colon Polyps â Colon polyps are benign growths, or clumps of cells, that form along the lining of the colon.