What is Dynamic Sitting?

synchro mechanism | dynamic sitting

Dynamic sitting occurs in an office chair that is fitted with a mechanism that allows the angle between the backrest and seat to change. By continuously changing this angle, you automatically stimulate, or activate various muscles in your lower back, core and legs. As a result, the blood flow through these muscles increases, bringing oxygen and other nutrients to the muscles and carrying away the waste products of muscle metabolism. By doing so, muscle fatigue and it’s associated pain is reduced, particularly in the lower back.  

Dynamic Sitting has long been acknowledged as the global benchmark for ergonomic comfort.

Office chairs fitted with either a Synchronous (synchro) or a Free-Float mechanism, encourage or aid Dynamic Sitting.

1. Synchro Mechanism

Synchro mechanisms are mechanical swivel & tilt devices that allow the angle of the chair backrest and seat to change in a fixed ratio. A synchro mechanism ensures that the movement of the backrest is always greater than that of the seat.
Most synchro mechanisms have a 2:1 ratio that moves the backrest 2 degrees for every 1 degree of movement in the seat.

backrest angle adjustment for choosing the best office chair
Synchro mechanisms allow the seat and backrest to move relative to each other in a fixed ratio

Synchro mechanisms promote Dynamic Sitting

The seat and backrest move together in a fixed ratio, where the backrest always moves more than the seat. If the mechanism is unlocked, it will be free-floating. In this position, the chair is dynamic and the backrest provides continual back support by moving with you.

Synchro mechanisms are fitted on most of our Executive and Task chair ranges

2. Free-Float Mechanism

A Free-Float mechanism allows you to independently, or separately, adjust the seat and backrest of the chair. This enables you to adjust the angles of the seat and backrest to suit your preferred sitting posture.

Free-Float mechanisms promote Dynamic Sitting and all orthopeadic office chairs use a Free-Float mechanism.
Like a synchro mechanism, if the Free-Float mechanism is unlocked, the chair is dynamic and the backrest provides continual back support as it moves with you.

free-float mechanim on orthopaedic chair
Free-Float mechanisms allow the seat and backrest to move independently or separately

Author: Mike Karle
Director at Karo Manufacturing (Pty) Ltd
4 Feb 2021 (rev 1)

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