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.
Causes of Blood in Stool. 1  Anal Fissure. If no diarrhea, most of these children have a small tear in the anus. 2  Strep Skin Infection. A Strep skin infection around the anus can also cause blood-streaked stools. 3  Bacterial Diarrhea. If also has bloody diarrhea, a gut bacterial infection may be the cause.  Red, but not Blood.
Infants might have green stool as a result of: 1  Not finishing nursing entirely on one side, thus missing some of the high-fat content breast milk, which affects the digestion of the milk. 2  Protein hydrolysate formula (for babies with milk or soy allergy). 3  Lack of normal intestinal bacteria in breast-fed infants.