Essentially, what's happening is that the constriction prevents further inflammation of joints and connective tissue, as well as constricting blood flow for a bit. Once the voodoo floss (or bicycle innertube split open) is removed, the blood flows back in to the area. For joints with large amounts of connective tissue, such as elbows and knees, this allows the blood to flush away some of the excess white blood cells that are further making the inflamed area worse. Beyond this, I would have to do more research.
Used for treating tendinitis:
This doesn't cure inflammation based injuries like tendinitis, or prevent all forms of it from ever bothering you again. However, it does provide some relief and allow you to continue training. Any time you are suffering from inflammation based problems like tendinitis or bursitis there is something you are doing that is causing the problem. Until you deal with that, you will be forced to repeat the triage over and over. For example, I found with my elbow tendinitis the major reason is that I did a lot of triceps work, but hardly anything for the biceps. I added in high rep curls to my routine, and the tendinitis went away.
There are several types of injuries, and voodoo floss as used in the video I linked to can only address inflammation. If you actually tore a ligament, sprained a joint, etc., you need to see a doctor. Usually rehab involves staying off the injured limb during the healing process, and re-initializing work with low weight high reps to strengthen the connective tissue and get blood flowing through the joint until it is completely healthy again.
Used for Mobility:
The floss isn't going to make you stronger, but it does change the way the muscles orient themselves when you are doing some types of stretching. What that means is you can intensify the stretch using the voodoo floss. Again, when you take the floss off, you have that rush of blood into the stretched area. The best bet is the rush of blood helps recovery. For a limited time your muscles may be a little larger similar to a bodybuilder pump, but that effect is strictly due to the extra blood post mobility work.
To deal with soft tissue inflammation issues (see tendinitis above), cryotherapy can make things worse by increasing the permeability of the lymph nodes. Essentially, the excess tissue fluids pour into the inflammed area instead of away.
Instead, the recommendation is to use compression, which can be any compression--including neoprene braces or sleeves. Instead of RICE (rest, ice, compression, elevation), the new recommendation (by the guy who designed the voodoo bands) is MCE:
- Move safely when you can, what you can
- Compress lymphatics and soft tissues (use bands, muscle contraction, clothing, normatec, etc)
- Elevate when you can.