S-Track, L-Track, SL, and iOpen: the rails in the massage chair

When comparing massage chairs, the focus quickly turns to programs and numbers. The track along which the rollers move is rarely mentioned, but it determines which parts of the body can actually be reached. There are four types of designs available.

S-Track: Contoured to the Spine

The "S" stands for sinusoidal, meaning wave-like. The brace follows the natural curve of the spine and guides the rollers from the neck down to the lower back. Because the back is not straight—but curves forward at the neck and curves backward again in the lumbar region—the rollers remain at a consistent distance from the body throughout.

This is the classic design and the standard one for entry-level models. It ends at the lower back.

L-Track: continue downward

An L-track is an extension. The track does not bend away from the pelvis, but continues under the buttocks and, depending on the model, all the way up to the thighs. This allows it to target the gluteal muscles and hip flexors—precisely the areas that tend to stiffen in people who sit for long periods of time.

People who experience pain in their lower back, buttocks, or thighs will notice the difference right away. Those who experience pain in their neck and between their shoulder blades will notice it less.

SL-Track: Both Together

"SL-Track" refers to the combination: the S-Track’s wave-like shape in the back, and the extension of the L-Track beneath it. This is currently the most common design in the mid-range and high-end segments. Some manufacturers also make the rail flexible so that it conforms to the shape of the back rather than dictating it.

iOpen: the split rail

iRest's top-of-the-line models feature a design that takes it a step further. In a standard SL-Track, the backrest and seat are firmly connected. When the chair reclines, the entire unit tilts, and your body maintains its posture throughout.

With iOpen, the backrest and seat move independently of each other, so that the chair can assume not only the zero-gravity position but also a completely flat position. Together with the footrest and the air cushions, which press the body against the backrest, this results in a true stretch: the upper body moves in one direction, and the pelvis in the other.

How to Tell What You Need When You're in the Store

When you try out the seat, point to the spot where it hurts and run the program. If the rollers stop well above your iliac crest, it’s an S-Track. If you can feel the rollers under your buttocks, it’s an L- or SL-Track.

And don't let the length alone sway your decision. A long rail that doesn't reach your shoulder is less helpful than a short one that works precisely there. Your body will sense where the rollers end up based on your height within the first few minutes: try sitting in it and test it out.

The guideexplains how the rollers move on the track: 2D, 3D, 4D, and 5D.

Back to the overview: Massage Chair Technology Explained in Simple Terms