Quad sets. 1  Sit with your leg straight and supported on the floor or a firm bed. (If you feel discomfort in the front or back of your knee, place a small towel roll under your knee.) 2  Tighten the muscles on top of your thigh by pressing the back of your knee flat down to the floor.
allergic reaction. allergic reaction in Medicine. allergic reaction n. A local or generalized reaction of an organism to internal or external contact with a specific allergen to which the organism has been previously sensitized. Examples from the Web for allergic reaction.
There are four types of hypersensitivity reaction, classified according to the way in which the ALLERGEN or ANTIGEN activates the reaction. The classic allergic reaction is the type I hypersensitivity reaction, with exposure to an external substance (the allergen) initiating the IMMUNE RESPONSE.