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.
Blood in stool. Find possible causes of blood in stool based on specific factors. Check one or more factors on this page that apply to your symptom. 1  In or on the stool. 2  In toilet bowl or on toilet tissue. 3  Drinking alcohol or caffeine. 4  Eating certain foods. 5  Straining during bowel movements. 6  Drinking more water. 7  Eating certain foods.