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Heating Up = Tightening?


Often in beauty magazines or advertisements, we see that heat can regenerate collagen and achieve a tightening effect. Is this really the case?

Whether it is laser, radiofrequency, infrared optical technology, etc., their ultimate goal is actually to increase the water content in the skin. Water? Yes! Water absorbs energy, which is then converted into heat energy, heating the dermis. So what happens when the dermis is heated?

First, we need to understand the characteristics of collagen. Hydrogen bonds connect the triple helix polymer of collagen. These protein aggregates and tissue together form elastic fibrils, which are caused by cross-linking between molecules. When collagen is heated, intra-molecular hydrogen bonds break and the previously mentioned triple helix unwinds into a gel of random molecules. At this point, the fibers become shorter and the tension increases as the molecular cross-links are maintained. After complex chemical reactions, the result is tighter skin. Subsequently, the tissue that has been altered by heat will reorganize, stimulating the formation of new collagen.

This phenomenon of collagen contraction was discovered and described in detail a long time ago. At what temperature does collagen start to contract? The general statement is that collagen contracts at 65°C. In fact, collagen contraction depends on time and temperature, so it does not only occur at a specific temperature, but rather it is a combination of time and temperature. For example, if heating occurs in one hundredth of a second, collagen contraction will only occur if the temperature exceeds 85°C; but if heating occurs for several seconds, collagen contraction will occur at 60°C to 65°C. Collagen contraction begins at 55°C and spreads to the reticular dermis at the bottom of the dermis by thermal conduction. Speaking of which, you can think of the principle of slow cooking. People who understand cooking should be able to understand it more easily!

This biological and chemical knowledge can assist in understanding medical beauty treatments. The promotion of heat achieving a tightening effect in advertisements is actually using a bit of biological common sense. Whether the claimed effect can be achieved depends on whether the skin reaches the appropriate temperature and time!