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.
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.