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.
Your baby's stools may be flecked with blood if she's constipated. This is because straining can cause tiny splits in the skin around her anus (anal fissures). These bleed when she has a bowel movement. Sometimes it could be a sign that her intestines are irritated by an infection or allergy. Always get any blood in your baby's stools checked out by your doctor. Take a look at our baby stool photo gallery to see what's normal and what's not.