Heating the tissue to 40-42º C generates a number of beneficial effects. First, collagen molecules respond to the heat by shortening. Collagen is the main supporting protein of our skin. Loss and aging of collagen is responsible for most of the sagging and wrinkling we associate with age. Shortening collagen with heat generates some immediate skin tightening in the Legend treatment area. Many patients see benefit from the first treatment due to the immediate tightening. This tightening is just a taste of the benefits to come. The heating of tissue and shortening of collagen also starts a healing response. It is the healing response that really gives some exciting benefits.