Pretty much all massage chairs that are not 100% airbag chairs have a roller system. The roller system goes up and down the spine, from the neck down to as far as the buttock muscles. The roller system consists of a roller track, one or two roller arms, roller “balls”, and an engine to move the roller mechanism up and down the spine electronically.
The roller “ball” unit is attached to the end of one or two massage arms, which in turn is attached to the track and moves up and down the spine. The roller “balls” come in either dual or quad arrangements. Dual rollers alludes to 2 rollers, one on each side of the spine, that do all the massaging. Quad rollers, or 4 rollers, have two rollers on each side of the spine. The roller balls work as a unit to go up and down the spine simultaneously to simulate massaging hands working the muscles on either side of the spine symmetrically.
Until recently, each ball moved in concert with the other ball(s); the pressure was equal on both sides of the spine. The new Inada Nest is the first massage chair to have the balls on either side of the spine work independently of each other for varying pressure depending on the tightness of the muscles on each side.
I want to talk about the difference between the dual and quad rollers. The vast majority of massage chairs have quad rollers (2 on each side of the spine). A relatively small group of chairs have the dual rollers, i.e. Luraco iRobotics 7, Ogawa Smart 3D, the Osaki JP 4S and 4D models, Apex Regent, and the now discontinued Navitas Sleep from Human Touch.
My experience of the two types of roller systems is that the dual rollers tend to be more aggressive, providing a deeper, more intense massage experience, while the quad rollers have a lighter, broader contact massage. You would think that more rollers (4) would give a more intense massage than less rollers (2). This is not to say that the quad roller system doesn’t offer an intense massage. Many 4-roller massage chairs do provide exactly that, but the dual roller system seems to dig a bit more into the spinal muscles. Let me explain why:
The roller track is fixed in an S shape. The roller arm is
what protrudes from the track into the spinal muscles. The force that “transmits” from the roller arm onto the roller balls and then into the muscles is dispersed among the roller balls. The greater the number of roller balls, the greater the dispersion of the massage force among the roller balls. The smaller the number of roller balls, the less the dispersion of the massage force. All the force and energy of the roller mechanism is channeled through two balls instead of four, which makes for more force going into the spinal muscles.
This is why chairs with dual rollers tend to feel more aggressive, as though the rollers are digging deeper into the spinal muscles. It is because the massage force and energy from the massaging mechanism is directed through only two roller balls.
If you sit on a chair with quad rollers and then sit on a chair with dual rollers you will notice a couple of things about the dual rollers:
- the rollers feel like they are digging deeper into the musculature, and
- you will feel like the roller massage is much more specific and localized.
If you prefer a deeper, more intense massage you may want to consider checking out a chair with dual rollers. Although quad massage chairs, particularly those with 3D roller depth adjustment, can still offer a very intense massage, it will never quite feel as deep or as intense or as localized as those with the dual rollers.
I hope this made sense!