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.
Here are just a few reasons why your baby may have blood in his stool: 1  An anal fissure, which is a small anal tear often caused by passing a hard stool. 2  A food allergy. 3  Maternal blood from delivery or from cracked, sore nipples.  An intestinal 1  infection. An intestinal disorder, such as colitis or intussusception.
Other conditions that can cause blood in the stool include: 1  Hemorrhoids. 2  Anal fissures. 3  Colon polyps. 4  Peptic ulcers. 5  Ulcerative colitis. 6  Gastroesophageal reflux disease (GERD) . 7  Crohn's disease. 8  Use of aspirin or nonsteroidal anti-inflammatory drugs (NSAIDs) .olorectal cancer affects the large intestine (colon) and the rectum. There are three kinds of stool tests: 1  Fecal occult blood test (FOBT). 2  For this test, you put tiny samples of your stool on a special card or cloth and send it to a lab. 3  The lab uses chemicals to find blood that you can't see with the naked eye.