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.
Intestinal Causes of Blood in Stools. Amoebic dysentery or commonly know as food poisoning, can also lead to blood in stools. Other condition called as ulcerative colitis, also leads to bleeding. It can be associated with mild to moderate abdominal pain with cramps and with mild fever.