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.
Blood in Baby's Stool. Babies can sometimes have blood in their stool that is caused by food allergies, a small anal tear or fissure, or even a temporary case of lactose intolerance. It might even be a drop of blood that came from a cracked nipple, which the baby then passed through his system.
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.