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.
What causes a baby or toddler to have bright blood in the stool (poop, poo) 1  An infant who is having bouts of screaming and drawing up the legs, maybe with vomiting as well, who then passes what looks like red currant jelly in the bowel motion may have intussusception and you need to see your doctor urgently - read more.