IASTM has its roots in the ancient Chinese practice of gua sha, but that does not mean we are not free to modernize the practice and adapt it to our growing knowledge of the body.
Gua sha is a method of scraping the skin with the intent of promoting the flow of chi in the body. The superficial scraping produces petechia and ecchymosis, which gua sha practitioners claim is evidence that the treatment is working.
Petechiae are the small purple or red spots that are evident when capillaries are damaged. Damage to the capillaries allows blood to escape the vessels and pool in the surrounding tissues. Ecchymosis is essentially the same process, but on a larger scale. Ecchymosis is also a fancy way to say bruising.
Scraping skin to the point of bruising provides no more clinical benefit than if the same amount of pressure is applied using a tool designed to avoid that response. Claims that the bruising stimulates blood flow and thereby promotes healing neglect the superficiality of the response. Petechiae form in the dermis, and provide no proof that the treatment is working on deeper structures, but rather demonstrate that the superficial layers have reached the threshold of the treatment they are able to endure.
The primary goal of instrument-assisted soft tissue mobilization is to identify and correct myofascial adhesions. Myofascial adhesions occur between deep fascial layers and muscle, and appropriate pressure must be applies to reach these structures. Certain IASTM tools have a sharp bevel, and a tissue response similar to gua sha will occur after short treatment periods with the use of these tools.
To maximize the effectiveness of treatment and speed healing time, it is important that the tools you choose are not the limiting factor in determining treatment time. If IASTM tools are appropriately beveled, some redness may occur at the treatment site, but no petechiae or ecchymosis should be present.