Combined Effects of Prolonged Sitting and Mental Stress on the Cardiovascular System

Not Applicable

Completed

• Conditions: Sedentary Behavior; Cerebrovascular Insufficiency; Cardiovascular Risk Factor; Mental Stress; Cognitive Change
• Interventions: Behavioral: Mental Arithmetic Test

• Registration Number: NCT04207333
• Lead Sponsor: University of North Carolina, Chapel Hill

Brief Summary

Prolonged sitting may pose a public health risk through its effects on the cardiovascular system, and may lead to impaired whole-body cardiovascular health, which includes both vascular and cerebrovascular function. These effects may interact with other environmental variables, such as stress. However, no study has investigated the combined effect of a mental stressor and prolonged sitting on vascular and cerebrovascular function. The combined effect of prolonged sitting and mental stress may lead to an exacerbated effect on vascular, cerebrovascular, and executive function. The investigators hypothesize that mental stress with the addition of prolonged sitting \[PS\] will result in a greater increase in peripheral, central and cerebral arterial stiffness and elicit a decrease in cerebral perfusion, total blood flow to the brain, middle cerebral artery velocity and executive function, compared to mental stress without prolonged sitting \[CON\]. The findings from this study may result in a public health message regarding sedentary behavior and stress, and will help elucidate the mechanisms behind acute vascular, cerebrovascular, and cognitive dysfunction during prolonged sitting.

Detailed Description

This study is a multi-visit (three in total) randomized crossover trial. During a single familiarization session, the research team will obtain informed consent, and will describe to participants the purposes and procedures of this study. They will then be exposed to all experimental devices on in a quiet, dimly lit and environmentally controlled room. Participants will return to the same location for two experimental conditions following these pre-assessment guidelines:

* Fasted (\> 12 hours), consuming only water.

* No caffeine consumption 12 hours prior to testing.

* No vigorous exercise 24 hours prior to testing.

* No alcohol consumption 24 hours prior to testing.

Participants will arrive to the Applied Physiology Laboratory between 6:00 and 10:00 a.m. fasted (for Visit 3: 2-5 days following the Visit 2). Participants will be fasted and refrain from caffeine intake for at least 12 hours, and alcohol and strenuous physical activity for at least 24 hours prior to arrival. Upon arrival, height and weight will be recorded followed by 10 minutes of quiet rest in the supine position. During these 10 minutes, the subject will be fitted with a Near Infra-Red Spectroscopy probe on the prefrontal cortex and medial gastrocnemius. The non-invasive continuous blood pressure, transcranial doppler, and Vicorder arterial stiffness devices will also be affixed to the participant during this time period during this time. Sitting periods will begin for both conditions once all devices are attached to the participant, the subject is shifted to an upright seated position, and at least 10 minutes of supine rest has been recorded. During the control (CON) visit, subjects will undergo a brief 20 minute sitting period. For the prolonged sitting (PS) condition, subjects will be asked to sit still and quietly for 2 hours while watching a non-stimulating documentary. Each condition will receive the mental stress at the conclusion of the sitting periods in both CON and PS. After exposure to the mental stress in both conditions, data collection procedures for this protocol will be completed. Arterial stiffness measurements will be made immediately after the mental stress, and then every 5 minutes, up to 30 minutes. Brain blood flow will be assessed by ultrasound after completion of the arterial stiffness measures. Finally, a battery of cognitive tests (Verbal Fluency Test and Trails A+B tests) will be administered to the participant.

Study Timeline

• Study First Submitted: 2019-12-16
• Study First Submitted QC: 2019-12-19
• Study First Posted: 2019-12-20
• Study Start: 2020-01-11
• Status Verified: 2020-03
• Primary Completion: 2020-05-01
• Study Completion: 2020-06-01
• Results First Submitted: 2021-02-16
• Results First Submitted QC: 2021-03-29
• Results First Posted: 2021-04-23
• Last Update Submitted: 2023-03-23
• Last Update Posted: 2023-04-18

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 6

Inclusion Criteria

• Healthy male or female

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Exclusion Criteria

• Any known cardio-metabolic disorders
• Taking medications known to affect cardiovascular function
• Report drug or alcohol abuse
• Report cigarette smoking
• Pregnant women

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Arm && Interventions

Group	Intervention	Description
Brief Sitting + Mental Stress, Then Prolonged Sitting + Mental Stress	Mental Arithmetic Test	Following 10 minutes of supine rest, participants will switch to an upright sitting position and remain seated for 10 minutes. Following the 10 minutes quiet rest the participants will be subjected to a 5 minute mental arithmetic test. Following a 2-5 day wash-out period, participants will be exposed to the other condition (prolonged sitting, followed by mental stress). For this condition participants will rest in the supine position for 10 minutes, then will be switched to an upright seated position. Participants will sit quietly for 120 min while watching a documentary, following which the participants will be subjected to a 5 minute mental arithmetic test.
Prolonged Sitting + Mental Stress, Then Brief Sitting + Mental Stress	Mental Arithmetic Test	Participants will sit for 120 min prior to being exposed to mental stress Following 10 minutes of supine rest, participants will switch to an upright sitting position and remain seated for 120 minutes while watching a documentary. Following the 10 minutes quiet rest the participants will be subjected to a 5 minute mental arithmetic test. Following a 2-5 day wash-out period, participants will be exposed to the other condition (brief sitting, followed by mental stress). For this condition participants will rest in the supine position for 10 minutes, then will be switched to an upright seated position. Following the 10 minutes quiet rest in the seated position, participants will be subjected to a 5 minute mental arithmetic test.

Primary Outcome Measures

Name	Time	Method
Change in Heart-middle Cerebral Artery Pulse Wave Velocity (Brain PWV)	Baseline and immediately following the acute mental stressor	Brain PWV (cm/s) is the velocity at which a pressure wave travels between the heart and cerebrovascular system. An increase in Brain PWV represents increased arterial stiffness (worse outcome).
Mean Change in Brachial-femoral Pulse Wave Velocity (bfPWV)	Baseline and immediately following the acute mental stressor	bfPWV (m/s) is the velocity at which a pressure wave travels between the brachial and femoral arterial segments. An increase in bfPWV represents increased arterial stiffness (worse outcome).

Secondary Outcome Measures

Name	Time	Method
Mean Change in Femoral-ankle PWV	Baseline and immediately following the acute mental stressor	Femoral-ankle PWV (m/s) is the velocity at which a pressure wave travels between the femoral-ankle arterial segments. An increase in femoral-ankle PWV represents increased arterial stiffness (worse outcome).
Mean Executive Function	following the acute mental stressor	Executive Function was measured at the end of each condition by recording the completion time of a trail making test. The trail making test was delivered using a tablet and the time to complete the test was recorded. Subject instructed to connect a set of 25 dots as rapidly as possible.
Neurovascular Coupling	following the acute mental stressor	Neurovascular Coupling reflects the cerebral blood flow during a cognitive task.
Mean Change Carotid-femoral Pulse Wave Velocity (PWV)	Baseline and immediately following the acute mental stressor	Carotid PWV (m/s) is the velocity at which a pressure wave travels between the carotid and femoral arterial segments. An increase in carotid PWV represents increased arterial stiffness (worse outcome).
Mean Change Augmentation Index	Baseline and immediately following the acute mental stressor	Augmentation Index is a measure of arterial wave reflection and calculated as augmentation pressure divided by central pulse pressure.

Trial Locations

Locations (1)

University of North Carolina at Chapel Hill; 🇺🇸 Chapel Hill, North Carolina, United States