Awhile back I came across this article that is mostly about what western type scientific studies have learned about scraping (Khoodt in Thai).  I wrote most of the following for my ongoing online apprentices, and thought I'd copy it over here to share more widely.  It was all phrased as gua sha since western medicine mostly knows about scraping through Chinese medicine, but I'm just gonna use the word scraping because they are just talking about the mechanical effects really, of the main motion of it that is found in all systems of medicine that use it.

Here is the article

And here is my condensation, simplified bullet points of what I got out of the article

•  Scraping produces temporary therapeutic petachiae (pronounced peh-ti-ki-ee, I know!). Petachiae is a western term for the red dotty/bumpy markings. It generally refers to mild vascular hemorrage, but in this case it is considered beneficial

•  Studies showed that scraping produced a 400% increase in superficial blood circulation (that’s a lot!) that stayed that way for about 7 minutes, and took 2 days to fully return to normal.  Think about this - in an area that has had blockage or is in any way dead/numb/depleted, scraping is going to bring an immediate huge flush of circulation, thereby removing toxins, and delivering nutrients to an area.

•  Every subject in the study experienced decreased or resolved pain and reported a greater sense of well being.

•  Scraping has provable anti-inflammatory and immune boosting effects - Yes, traditional medicine has known this forever and day.  Read on to see the western perspective of why.

• It can reduce a fever and alter the course of an acute infectious illness, as well as reduce inflammatory symptoms in chronic illness.  Again, traditional medicine already knew this.

• Okay, here is where we get to the oh so interesting why.  Cruel studies on a mouse showed that scraping upregulates (meaning increases) gene expression for an enzyme that is an anti-oxidant and cytoprotectant (meaning a thing that protects the cells from harm), heme oxygenase-1 (HO-1), was present at multiple internal organ sites immediately after treatment and over a period of days following gua sha treatment.
(what that just said up there is that it causes an increase in an enzyme that protects cells, and this was found around many organs.)

•  Also, this enzyme is anti-inflammatory and antioxidive - it can reduce allergic inflammation, AND it boosts immune response AND it relieves symptoms of Hepatitis B and C, AND it might heal internal organs AND it helps with all kinds of other nasty things like asthma, organ transplant rejection, inflammatory bowel disease and experimental autoimmune encephalomyelitis.  No, I'm not saying that scraping is the new/ancient cure all.  But it has been used for a lot more than muscle aches over the centuries.

• This is all in addition to all the stuff we already knew that scraping can do - Here is a nice list I made that combines things this article said, with stuff I already had on it from Thai medicine.

Releasing excess heat
Treating colds, flus and fevers
Treating many forms of headache including tension affected migraines
Dispersing stagnation
Releasing fascial restriction
Breaking down scar tissue
Reducing inflammation
Treating heatstroke
Relaxing bound muscles
Releasing adhesions
Releasing accumulated waste
Increasing circulation (400% increase in surface circulation of blood)
Releasing stuck wind
Reducing inflammatory symptoms in chronic illness

Scraping is done throughout southeast Asia and in northern Thailand you can find traditional doctors who specialize in it, complete with ceremony and incantations to boost the effect and protect the recipient.  But scraping is also kitchen medicine.  It's done by mothers to the children, and friends to friends.

Knowing Thai medical theory takes it from the realm of folk healing into more advanced therapy, and it is an amazing addition to any Thai bodywork practice.  Personally it's a technique that I have a particular affinity for.  Mostly I use porcelain soup spoons to do scraping, but you can see part of my collection of traditional tools in the photo below.