Acceleration Sensors Measure Sitting Activity on Dynamic Office Chairs

MSR145 mini data loggers detect movement patterns while seated

According to current studies, prolonged static sitting in the workplace has a dramatic effect on the quality of life. A new generation of ergonomic office chairs can promote greater physical activity and thus counteract the negative side effects of sitting for long periods of time.

Author: Daniel Baumgartner, Prof. of Biomechanics ZHAW, Zurich University of Applied Sciences

Together with the biomechanics at Zurich University of Applied Sciences (ZHAW), rotavis AG, a start-up company based in Winterthur, developed an innovative technology that promotes active sitting.

Office chairs by rotavis: The new dynamic sitting technology stimulates the musculature of trunk and reduces back tension. Image source: rotavis AG

The moveable seat enables movements of the pelvis and spine in a similar way to the salsa swing, thus stimulating the muscular system of the user’s back. The increased mobility is conducive to the stimulation of the musculoskeletal system of the spine and intervertebral discs.

Test method

In order to develop a physiological dynamic adapted to the body, in a first step 57 test subjects were measured in the movement analysis laboratory of the School of Health Professions at the ZHAW. The researchers analysed the natural movement of the spine in order to reproduce it on the innovative chair. This was followed by a user study with a total of 30 test subjects in collaboration with a larger, locally based insurance company in Winterthur. The 30 prototype chairs were fitted with MSR145 mini data loggers by MSR Electronics GmbH on the moveable seat in order to detect the movement patterns during active sitting time.

Data loggers used

Data Logger MSR145, waterproof design housing with 900 mAh battery, integrated 3-axes acceleration sensor and micro SDcard.Using a 3-axis acceleration sensor (±15 g), the MSR145 mini data loggers used in the study continuously recorded the movements in all three axes at a measurement frequency of 10 Hz over a period of two weeks. The data loggers were equipped with a slot for a microSD card to ensure a storage capacity of one billion measured values. MSR Electronics GmbH, the manufacturer of the loggers, provides MSR-Setup, -Reader, -Viewer and -Online pc software for configuring the data loggers and analysing the data.

Measurement results

For an average working day in a seated position, the seat that moves sideways was activated. Doubling the active sitting time on the chair resulted in a marked increase in the intensity of movement of the back. This clearly demonstrated the goal of increasing activity. A further study is planned, which is intended to also show the reduction of pain achieved with the new dynamic office chair.

The chairs are now available and can be purchased online at www.rotavis.ch.

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