Effect of Alternating Postures on Cognitive Performance
Condition: Sedentary Lifestyle
Study type: Interventional

Summary: 
      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
      short-term effect of alternating working postures on cognitive performance for healthy
      people.
    

Detailed description: 
      Measurements were made in a laboratory. They were made on two different days with an interval
      of 7 days between sessions. 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 heart rate variability (HRV), 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 long version of the International
      Physical Activity Questionnaire (IPAQ, only on the first day of measurement). 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
      level. Baseline heart-rate was calculated after a 20 minute rest for a 5 minute interval.

      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.

      For the intervention group, the cognitive blocks were executed in an alternating posture (sit
      - stand - sit - stand - sit) either on the first or the second day of measurement (cross-over
      design). To generate control periods, this procedure was executed in an sitting posture only
      (sit - sit - sit - sit - sit) for the non-interventional day. For the control group, both
      days of measurement were executed in sitting posture only (sit - sit - sit - sit - sit ).

      In the third (final) phase participants were asked to estimate their workload by means of the
      Task Load Index questionnaire developed by the National Aeronautics and Space Administration
      (NASA-TLX), followed by a 30 minutes resting phase in a sitting posture. During both 30 min
      resting phases (initial & final) participants watched documentaries and were encouraged not
      to talk.

      Heart-rate and trunk movements were measured from the start of the study protocol until the
      next morning by means of an mobile ECG-recorder.
    

Intervention name(s): Alternating working postures, first day; Alternating working postures, second day
Intervention type(s): Other; Other
Intervention description(s): On the first day of measurement participants execute five test battery trials in alternating postures (sit/stand/sit/stand/sit). On the second day of measurement participants execute the test battery in a sitting posture (sit/sit/sit/sit/sit).; On the first day of measurement participants execute five test battery trials in a sitting posture (sit/sit/sit/sit/sit). On the second day of measurement participants execute the test battery in alternating postures (sit/stand/sit/stand/sit).
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: None (Open Label)
Keywords: postural changes; alternating postures; Cognitive performance; Height-adjustable desk; Worksite