The 4D massage chair gets its name from the advanced capabilities of the massage roller. True 4D is a 3D massage chair that is also an L-Track or an armchair that can massage the back and buttocks, providing pressure to the gluteal muscles and hamstrings. These chairs are quite rare, since the technology is new and some don't work very well, but the Positive Posture Brio is the best there is.
Technically, they should be called “3D L-Track”, but 4D sounds better. This wide adjustable intensity range is very popular in homes where more than one user will be using the chair. If you're looking for a deep therapeutic massage in the buttock area, then an L-shaped track is definitely for you. So you could say that all 3D massage chairs are also 4D.
S-Track massage chairs follow the curvature of the spine from the neck to the lower part of the spine in an S-shape. As you can see in this diagram, the rollers on an L-Track chair usually start just below the neck and follow the curvature of the spine and around the gluteal muscles and hamstrings. If you're buying a massage chair and you've done some research, or if you already have a massage chair and want to improve it, you've probably seen several mentions of the “D”.
With the guidance of professional holistic massage therapists, 4D massage movements were designed to add variations in speed to each massage style. This allows users to customize their massage experience to their own needs and preferences. Recently, premium massage chairs have added the possibility of extending the rollers to the back and putting them back in the chair. From the first massage chair and until very recently, all the available options were 2D massage.
Some manufacturers claim that their chairs work with a 3D movement and that they can adjust speed, which is supposedly the fourth “D”. However, all massage chairs can adjust speed, so this doesn't make any sense.
In conclusion, 4D massage chairs are 3D L-Track chairs that provide pressure to gluteal muscles and hamstrings. They offer a wide adjustable intensity range that allows users to customize their massage experience according to their needs and preferences.