A defensive maneuver in which one or more linebackers or defensive backs, who normally remain behind the line of scrimmage, instead charge into the opponent's backfield. However, in the 3-4 defense, one linebacker typically rushes the passer with the three down linemen.
Blisters are commonly caused by friction from tight shoes, herpes, chicken pox, poison ivy and allergic reactions. More uncommon are disorders that only cause blisters on the hands and feet. See your doctor for an accurate diagnosis if you have blisters on your hands and feet, particularly from an unknown cause.
Friction blisters. 1  Friction causes most blisters on the hands and feet. 2  Definition: A raised pocket of clear fluid covered by skin. 3  Cause: A friction blister is the result of friction and shear forces separating off the top layer of the skin. Friction Blister: Raised pocket of clear fluid, covered by skin. 2  Friction blisters usually occur on the palms, fingers, heels or toes. 3  Blood Blister: Raised pocket of bloody fluid, covered by skin. 4  Dark red or purple in color. 5  A blood blister can occur when the skin gets pinched (in a hinge or a closing door).