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.
1 White blood cells in the stool may be caused by inflammation of the intestines, such as ulcerative colitis, or a bacterial infection. 2  Rotaviruses are a common cause of diarrhea in young children. 3  If diarrhea is present, testing may be done to look for rotaviruses in the stool. Stool with a high pH may mean inflammation in the intestine (colitis), cancer, or antibiotic use. 2  Blood in the stool may be caused by bleeding in the digestive tract. 3  White blood cells in the stool may be caused by inflammation of the intestines, such as ulcerative colitis, or a bacterial infection.