Blood Pressure Regulation, Cognitive Function, Sedentary Time
Conditions
Keywords
Standing Time, Occupational Health, Stroop Task, Carotid Intima-Media Thickness, Head-Up Tilt, Objectively Measured Activity
Brief summary
This project will determine the short-term 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. The main outcome is habitual activity patterns, assessed by the thigh-worn inclinometer (activPAL). All participants will be equipped with an activPAL and have their cardiovascular and cognitive function assessed at baseline and 4 weeks. Participants in the intervention group will use a standing desk converter for 4 weeks, while the wait-list control group will be encouraged to maintain their regular activity patterns. Researchers will compare the intervention and control groups to see if using the standing desk converter will increase standing time and lower sedentary time, improve cognition, and improve blood pressure regulation.
Detailed description
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.
Interventions
BEHAVIORALStanding Promotion Intervention
Participants will be provided with a standing desk converter to set on top of their existing desk for 4 weeks.
Sponsors
Olga Theou
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
OTHER
Masking
SINGLE (Outcomes Assessor)
Masking description
The control group will receive no intervention and will be inherently not blinded to their group allocation. All analyses will be completed by an individual blinded to participants' group allocation.
Intervention model description
A block randomization strategy will be implemented to ensure equal allocations to intervention/control groups in groups of 6 (3 per group). Even and odd numerals will represent designation to the Intervention and Control groups, respectively. For example, if the first 3 participants are randomized to the control group, the next 3 will be allocated to the intervention group. To ensure all control participants will be offered the intervention after their control period, the first 3 participants for the final block of 6 (block 7) will be randomized to the control group first. Randomization will occur after Visit 1 assessments are complete.
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
Yes
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
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| ActivPAL monitors | Change from baseline (week 0) activity to post intervention (week 4). | Habitual sedentary and physical activity data will be recorded through the thigh-worn monitor. Information obtained from the 3 monitors will provide information regarding time spent lying, sitting (bent vs straight leg) and standing. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Cognition | Change from baseline (week 0) activity to post intervention (week 4). | The computerized Stroop task will consist of the three conditions mentioned above: simple, interference, and switching. The computer program used to administer the task records accuracy and reaction time. |
| Brain Activation: Functional Near Infrared Spectroscopy | Change from baseline (week 0) activity to post intervention (week 4). | Functional Near Infrared Spectroscopy (fNIRS) is a well-established modality of neuroimaging that can detect differences in blood-oxygen-level dependent (BOLD) signal, allowing one to make inferences on brain activity. fNIRS sensors consist of light sources that emit near-infrared light, as well as photo diodes that detect the levels of the light at the two different frequencies. As each wavelength of light is known to be absorbed differently by oxy- and deoxyhemoglobin, one can infer cerebral oxygenation via the relative absorption of each wavelength through the application of a modified beer-lambert law. The NIRScout system contains 8 LED sources and 16 detectors (optodes), which can be placed in customized configurations to measure from different regions of the brain. The sources and detectors are held in place through an elasticized cap that fastens with Velcro under the chin. |
| Electrocardiography | Change from baseline (week 0) activity to post intervention (week 4). | Heart rate will be monitored via electrocardiography (ECG). ECG is the non-invasive, passive recording of electrical cardiac activity at the surface of the skin. This will be recorded at a sampling frequency using a dedicated data acquisition system (PowerLab, ADInstruments) and analysis software (Lab Chart, ADInstruments). |
| Continuous Finger Blood Pressure Recording (Finapres Medical Systems) | Change from baseline (week 0) activity to post intervention (week 4). | A small cuff used to measure continuous, non-invasive blood pressure will be placed around the middle or index finger. When in use, the cuff will inflate with air and gently squeeze the finger. This will be recorded at a sampling rate of 200Hz using a dedicated data acquisition system (PowerLab, ADInstruments) and analysis software (Lab Chart, ADInstruments). |
| Upper Arm Blood Pressure Measurements | Change from baseline (week 0) activity to post intervention (week 4). | A semi-automated patient vital signs monitor (Carescape v100®, General Electric Healthcare) will be used to record resting, seated blood pressure from the upper left arm (i.e., the brachial artery). Additional measurements will be recorded during the various rest periods. |
| Carotid Artery Structure | Change from baseline (week 0) activity to post intervention (week 4). | Internal carotid artery intima-media thickness will be imaged on the right-side. A minimum of two minutes of beat-by-beat carotid images during supine rest, the initial tilt, and the final tilt period will be collected. |
| Carotid Artery Function | Change from baseline (week 0) activity to post intervention (week 4). | Internal carotid artery function changes in blood flow to head-up tilt will be measured via ultrasonography. A minimum of two minutes of beat-by-beat carotid images during supine rest, the initial tilt, and the final tilt period will be collected in the right-side common carotid artery. |
Countries
Canada
Contacts
PRINCIPAL_INVESTIGATORMyles W O'Brien, PhD
Department of Medicine and Department of Physiotherapy, Dalhousie University
Outcome results
None listed