Mid-term Effect of a Novel Sit-to-stand Workplace (ACTIVE OFFICE) on Cognitive and Physiological Parameters

Prolonged sitting is a risk factor for cardiovascular and musculoskeletal diseases, diabetes, several types of cancer and all-cause mortality. In combination with static and awkward postures, the prevalence of musculoskeletal diseases can increase further. Although the implementation of sit-to-stand or active workstations can help to reduce sitting time, improve physical activity at work and promote health benefits, it might also lead to changes in cognitive functions such as productivity The purpose of this study is to evaluate the mid-term effect of a novel two desk sit-to-stand workplace on sitting time as well as physiological and cognitive parameters for healthy people of working age in comparison to their traditional workplace.

Measurements were made both in the field and in a laboratory. Field measurements were made and processed continuously over the 23-week intervention period. Laboratory measurements were made on two different days, one day prior to intervention, and one day following intervention (due to cross-over design, each subject underwent 4 total days of laboratory measurements). Field measurements were collected automatically at the participants' workstation in their working office.

Laboratory tests were conducted in a controlled, simulated work-space located at the University of Applied Sciences Campus Linz. All laboratory measurements were made in a controlled laboratory at the campus site Linz of the University of Applied Sciences Upper Austria. Temperature, air flow, humidity, lighting conditions (artificial light only) and noise level were controlled and set to be consistent with the subjects' typical working environment.

During the laboratory measurements, subjects either stood or sat upright in an ergonomic office chair, according to the study protocol. Subjects were encouraged to work as fast and as accurately as they could. To ensure identical testing conditions between subjects and to not unduly influence physiological parameters such as salivary cortisol level or heart rate variability, subjects were required to minimize excessive movement (e.g. standing up during the sitting periods).

In the first (initial) phase, participants were familiarized with the study protocol. Sitting time and weekly physical activity were determined via the IPAQ-questionnaire. Examples of each cognitive test implemented in the cognitive phase were executed according to their guidelines. A 30 minute break in a sitting posture was used to ascertain baseline heart-rate and cortisol level. Baseline heart-rate was calculated after a 20 minute rest for a 5 minute interval and saliva samples were collected at the end (30min) of the break.

In the second (cognitive) phase subjects participated in a test battery containing five blocks. Each block consisted of a working speed test (text editing task), an attentional test (d2R-test of attention) and a reaction time test (Stroop-test). These tests lasted for 30 minutes to fulfill recommendations regarding postural changes. To simulate "common" working conditions (computer based and non-computer based tasks), digital (text editing task, Stroop-test) as well as pen \& paper (d2R-test) versions of the implemented tests were used. All blocks were executed in alternating postures (sit - stand - sit - stand - sit) and at the end of each block - after a 5 minute break - salivary samples were collected. The order of posture was not changed within groups or time.

In the third (final) phase participants were asked to estimate their workload by means of the NASA-TLX questionnaire followed by a 30 minute resting phase in a sitting posture. During both 30 min resting phases (initial \& final) participants watched documentaries and were encouraged not to talk.

Salivary samples were collected after each break during the study protocol and on the following morning, 20 minutes after waking up, to ascertain cortisol awakening response (CAR). Salivary samples were centrifuged and stored at -80 °C for subsequent testing using a chemiluminescent immunoassay.

Heart-rate and trunk movements were measured from the start of the study protocol until the CAR measurement.

Eligibility Criteria:
Inclusion Criteria:

* Healthy Caucasian (no acute or chronic diseases)
* Normal weight or slightly overweight (BMI: 18.5 - 27.5 kg/m²)
* Regularly working in sedentary office environments
* Regular computer users
* Fluent German speakers
* Consented to participate

Exclusion Criteria:

* Heavily overweight \& Obesity (BMI \> 27.5 kg/m²)
* Short office stay duration (\< 8 h / day or \< 20 h / week)
* Experience in sit-to-stand workstations
* Acute or chronic diseases
* Inability to stand
* Visual impairments that had not been corrected
* Color blindness
* People planning to change their physical activity level
* Regular smokers (\> 1 cigarette /day)
* Not consented to participate