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.
Internal hemorrhoids are very painful and can cause a child to strain and bleed while passing a stool. Antibiotics can upset the normal flora of the colon and lead to constipation. Medication. Some cough mixtures and pain medication have constipation as a side-effect. Chronic stress can cause constipation.