The Effect of Tea Breaks on Cerebrovascular Perfusion During Desk Work

Study Overview
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Brief Summary
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Sedentary behaviour of healthy subjects may have a detrimental impact on cerebral blood flow as well as cognitive measures related to mood and alertness. In this study we focus on the impact of leaving the desk to consume a cup of tea at regular intervals during a sedentary working day.

Detailed Description
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Prolonged desk work has detrimental impact on cerebral blood flow as well as cognitive measures related to mood and alertness caused. These effects might be prevented by taking short breaks with physical activity. Usually, desk workers have short breaks during office times for either a visit to the restroom or to enjoy for a moment a (hot) drink. Consumption of tea has been associated with benefits related to attention, alertness, mood and creativity. This study focuses on the impact of physically leaving the desk to prepare and consume a cup of tea at regular intervals during a sedentary working day.

Official Title
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The Effect of Tea Breaks on Cerebrovascular Perfusion During Desk Work

Conditions
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Cerebrovascular Circulation, Affect

Intervention / Treatment
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* Other: Tea
* Other: Water


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy males and females, age at screening > 18 and < 60 years; BMI > 18 and < 30 kg/m2 Apparently healthy Agreeing to be informed about medically relevant personal test-results by a physician Informed consent signed Sedentary working individuals (≥6 hours desk work per day, ≥4 days per week) Exclusion Criteria: Reported physical exercise ≥4 hours per week Taking medication (including food supplements and traditional medicines) which may interfere with study measurements, as judged by the PI Reported participation in another nutritional or biomedical trial (involving an intervention of at least 1 week) 3 months before the screening or during the study Reported participation in night shift work 2 weeks prior to screening or during the study. Night work is defined as working between midnight and 6.00 a.m. Reported consumption of > 14 units (female subjects) and > 21 units (male subjects) alcoholic drinks in a typical week. Reported use of any nicotine containing products in the 6 months preceding the study and during the study itself. If female, is pregnant (or has been pregnant during the last < 3 months ago) or will be planning pregnancy during the study period. If female, is lactating or has been lactating in the 6 weeks before screening and/or during the study period. Reported weight loss/gain (> 10%) in the last 6 months before the study. Being an employee of Unilever or an employee or a student working in RISES LJMU that is directly involved in this study.

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 60 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Randomised, full cross-over study
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Tea-water<br>Tea before water | Other: Tea<br>* Subjects walk to a nearby area and prepare a cup of 150 ml tea once every hour. The tea is consumed whilst being seated at their desks.<br>Other: Water<br>* 150 ml water is served to subjects once every hour. The water is consumed whilst being seated at their desks.<br>|
| Experimental: Water-tea<br>Water before tea | Other: Tea<br>* Subjects walk to a nearby area and prepare a cup of 150 ml tea once every hour. The tea is consumed whilst being seated at their desks.<br>Other: Water<br>* 150 ml water is served to subjects once every hour. The water is consumed whilst being seated at their desks.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in cerebrovascular perfusion of tea versus water | Cerebrovascular perfusion measured as middle cerebral artery velocity | Immediately before and immediately after each of the two 6-hour interventions. The 'before' results will be added to the mixed model as a covariate. | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in cerebrovascular auto-regulation gain of tea versus water | Dynamic cerebrovascular autoregulation is assessed via squat-stand manoeuvres performed to elicit oscillations in blood pressure within the high-pass filter frequency range (<0.20 Hz) of the cerebrovascular. Squat-stand cycles are performed at 0.2 Hz (2.5-seconds squatting, followed by 2.5-seconds standing) and at 0.1 Hz (5-seconds squatting, followed by 5-seconds standing) for 5-minutes each, separated by a 5-minute rest. Transfer function analysis is conducted on the beat-to-beat blood pressure and middle cerebral artery blood flow velocity mean signals to produce values of gain (damping effect of Cerebrovascular autoregulation on the magnitude of blood pressure oscillations). | Immediately before and immediately after each of the two 6-hour interventions. The 'before' results will be added to the mixed model as a covariate. | 
| Difference in cerebrovascular auto-regulation phase of tea versus water | Dynamic cerebrovascular autoregulation is assessed via squat-stand manoeuvres performed to elicit oscillations in blood pressure within the high-pass filter frequency range (<0.20 Hz) of the cerebrovascular. Squat-stand cycles are performed at 0.2 Hz (2.5-seconds squatting, followed by 2.5-seconds standing) and at 0.1 Hz (5-seconds squatting, followed by 5-seconds standing) for 5-minutes each, separated by a 5-minute rest. Transfer function analysis is conducted on the beat-to-beat blood pressure and middle cerebral artery blood flow velocity mean signals to produce values of phase (temporal relationship between changes in blood pressure and middle cerebral artery blood flow velocity). | Immediately before and immediately after each of the two 6-hour interventions. The 'before' results will be added to the mixed model as a covariate. | 
| Difference in cerebrovascular auto-regulation coherence of tea versus water | Dynamic cerebrovascular auto-regulation is assessed via squat-stand manoeuvres performed to elicit oscillations in blood pressure within the high-pass filter frequency range (<0.20 Hz) of the cerebrovascular. Squat-stand cycles are performed at 0.2 Hz (2.5-seconds squatting, followed by 2.5-seconds standing) and at 0.1 Hz (5-seconds squatting, followed by 5-seconds standing) for 5-minutes each, separated by a 5-minute rest. Transfer function analysis is conducted on the beat-to-beat blood pressure and middle cerebral artery blood flow velocity mean signals to produce values of coherence (linearity of the relationship between the changes in middle cerebral artery blood flow velocity and blood pressure). | Immediately before and immediately after each of the two 6-hour interventions. The 'before' results will be added to the mixed model as a covariate. |