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.
Blood in the stools can be a frightening to see. While some causes of bloody stools are harmless such as hemorrhoids, other reasons for bloody stools can mean a more serious illness like colon cancer. If you notice blood or color changes in your stool, see your doctor immediately to rule out a serious problem.