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.
Occult blood in the stool has many of the same causes as rectal bleeding, and may be associated with the same symptoms as more active bleeding. For example, slow bleeding from ulcers, colon polyps, or cancers can cause small amounts of blood to mix and be lost within the stool.