Standing Desk Converter & Habitual Posture

Background: Too much sedentary time (time spent sitting, reclining, or lying) leads to health problems such as cognitive impairments or cardiovascular disease. A lot of sedentary time is accumulated while working at a desk (e.g., computer work, studying, etc.). Standing desk interventions have provided mixed support as to whether they can reduce habitual sedentary time, with the need for more controlled interventional studies. It remains to be determined if a simple standing desk converter (i.e., a height-adjusted desk that can be set on top of a traditional sitting desk) increases standing time (i.e., not sedentary) and/or decreases sedentary time. Worse cognitive health and higher blood pressure are linked to a greater risk of chronic conditions such as dementia and cardiovascular disease, respectively. More physical activity improves cognition and blood pressure regulation, but whether standing more also translates to these brain and heart improvements is unclear.

Main Objective: The goals of this project are to determine the impact of a standing desk converter on: 1) objectively measured physical activity and posture levels, and 2) brain (cognition) and heart (blood pressure regulation) function. It is expected that using the standing desk converter will increase standing time and lower sedentary time, improve cognition, and improve blood pressure regulation.

Methodology: For the proposed project, we will assess free-living posture, cognition, and blood pressure regulation before and after 4-weeks of either using a standing desk converter (intervention) or a wait-list control. The study population targets adults who use a traditional seated desk for a minimum of 20 hours per week and do not already use a standing desk. Free-living activity will be assessed using activity monitors (activPALs) worn for 7-days before and after either the control period or intervention. Cognition will be assessed using a computerized Stroop task that records accuracy and reaction times to selecting the colour of the word or the word itself (e.g., word BLUE written in red font). Progressively more challenging Stroop conditions will be used to assess different aspects of cognition. During the Stroop, cerebral oxygenation will be determined using near-infrared spectroscopy. Beat-by-beat blood pressure (via finger cuff), heart rate (via electrocardiogram), and internal carotid artery size and red blood cell velocity (via ultrasound) will be measured while lying down and in response to 20 minutes of 60-degree passive head-up tilt that tests blood pressure regulation. The proposed study will yield new knowledge as it relates to real-life posture interventions that promote healthier movement and investigates whether standing converters lead to improvements in brain and heart health.

Significance: The proposed study will yield new knowledge as it relates to real-life posture interventions that promote healthier movement and investigates whether standing converters lead to improvements in brain and heart health.

Inclusion criteria

• 18 years of age or older
• Are normotensive, cognitively healthy, and do not have a history of fainting while standing
• Are able to stand for 10 min without assistance (e.g., require a walker, person assistance)
• Are not allergic to clear medical adhesive (TegadermTM, 3M) used to secure the activPAL activity monitors
• Use a seated desk at least 20 hours/week in the last month and do not use a standing or active desk already
• Females who are not pregnant, breastfeeding or planning on becoming pregnant prior to entry into the study

Exclusion criteria

• Younger than 18 years old
• Hypertension (resting systolic pressure >139 mmHg and/or diastolic pressure >89 mmHg)
• Have a diagnosed cognitive impairment
• Have a history of orthostatic hypotension/intolerance and/or fainting while standing
• Cannot stand for at least 10 min without assistance (e.g., require a walker, person assistance)
• Have a known allergy to the clear medical adhesive (TegadermTM, 3M)
• Use a seated desk less than 20 hours/week, use a standing or active desk already, or use a desk for more than 20 hours/week but not in the last month
• Females who are pregnant, breastfeeding or planning on becoming pregnant prior to entry into the study