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Sitting time is high in older adults and has been shown to temporarily impair endothelial function and blood pressure. Flavanols, plant-derived compounds, acutely enhance endothelial function and reduce Blood pressure in older adults. The aim of this study is to investigate whether acute ingestion of cocoa flavanols can improve peripheral endothelial function and blood pressure during prolonged sitting in healthy older adults.
In a randomised, double-blinded, cross-over, placebo-controlled human study, 20 healthy older adults will consume either a high-flavanol (695 mg) or low-flavanol (5.6 mg) cocoa beverage immediately before a 2-hour sitting bout. Flow-mediated dilation (FMD) of the superficial femoral (SFA; primary outcome) and brachial (BA) arteries, and blood pressure, were assessed before and after sitting. Microvasculature haemodynamics were assessed in the gastrocnemius before, during, and after sitting. It is hypothesized that the high flavanol cocoa will prevent declines in brachial and superficial femoral Flow-mediated dilatation post sitting.
Older individuals are estimated to spend more than 10 hours in their waking day in sedentary activities , which can include sitting bouts lasting up to 5.4 hours/day . Greater sedentary time was found to be associated with a significantly increased risk of cardiovascular diseases and all-cause mortality. Several experimental studies have shown that even just one isolated episode of prolonged sitting (from 1 to 6 hours) has detrimental effects on human endothelial function, as measured by flow-mediated dilation (FMD).
Flavonoid-rich foods are typically consumed in high amounts in cardioprotective diets, with evidence from both observational and Randomised Controlled Trials showing flavonoids to improve biomarkers of cardiovascular health. Flavanols, a sub-group of flavonoids present in unprocessed cocoa, have been extensively shown to act quickly within the vasculature, improving both brachial Flow-mediated dilatation and lower-limb common femoral artery (CFA) Flow-mediated dilatation within 2 hours of intake in older adults.
The aim of the current study is to examine whether acute consumption of cocoa flavanols prior to a 2-hour bout of uninterrupted sitting can be beneficial in improving endothelial function (as measured by Flow mediated dilatation) in the upper-limb Brachial Artery (BA) and lower-limb Superficial Femoral Artery (SFA) in older adults, as well as downstream, muscle microvascular function. We will further investigate whether cocoa flavanols can prevent sitting-induced increases in blood pressure in older adults. We hypothesise that cocoa flavanols would be effective at rescuing upper- and lower-limb Flow-mediated dilatation and improve blood pressure during uninterrupted sitting in older age
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| High-flavanol cocoa powder | Experimental | 12 g of fat-reduced natural cocoa powder containing 695 mg of total flavanols, including 150 mg (-)-epicatechin |
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| Low-flavanol cocoa powder | Placebo Comparator | 12 g of fat-reduced alkalized cocoa powder containing 5.6 mg of total flavanols |
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| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| High-flavanol cocoa powder | Dietary Supplement | 12 g of a fat-reduced natural cocoa powder containing 150 mg of (-)-epicatechin, and 695 mg of total flavanols |
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| Measure | Description | Time Frame |
|---|---|---|
| Flow-mediated dilatation of the superficial femoral artery | Flow-mediated dilatation (FMD) of the superficial femoral artery. Expressed as percent FMD: change in brachial diameter from baseline to peak dilation following 5 minutes of arterial occlusion. Brachial artery diameter and blood flow will be measured using Doppler ultrasonography (uSmart 3300, Terason). | Change from pre-intervention baseline to 2 hours post intervention /2 hours post sitting |
| Measure | Description | Time Frame |
|---|---|---|
| Flow-mediated dilatation of the brachial artery | Flow-mediated dilatation (FMD) of the brachial artery. Expressed as percent FMD: change in brachial diameter from baseline to peak dilation following 5 minutes of arterial occlusion. Brachial artery diameter and blood flow will be measured using Doppler ultrasonography (uSmart 3300, Terason). | Change from pre-intervention baseline to 2 hours post-intervention/ 2hours post sitting |
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Inclusion Criteria:
Exclusion Criteria:
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| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| School of Sport, Exercise & Rehabilitation Sciences, University of Birmingham | Birmingham | West Midlands | B15 2TT | United Kingdom |
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| Type | Includes Protocol | Includes SAP | Includes ICF | Document Label | Document Date | Document Uploaded Date | Document File Name |
|---|---|---|---|---|---|---|---|
| ICF | No | No | Yes | Informed Consent Form | Sep 14, 2021 | Nov 28, 2025 | ICF_000.pdf |
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| ID | Term |
|---|---|
| D057185 | Sedentary Behavior |
| ID | Term |
|---|---|
| D001519 | Behavior |
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| Low-flavanol cocoa powder | Dietary Supplement | 12 g of a fat-reduced alkalized cocoa powder containing 5.6 mg of total flavanols |
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| Tissue oxygenation index (TOI) of Gastrocnemius skeletal muscle | Tissue Oxygenation Index (percent TOI) will be assessed by functional Near-Infrared Spectroscopy (fNIRS) on the medial head of the gastrocnemius muscle during 5 min of superficial femoral arterial occlusion and 5 min of post-occlusion (reactive hyperaemia). The NIRS device measures changes in chromophore concentrations of oxyhaemoglobin (O2Hb) and deoxyhaemoglobin (HHb), providing depth-resolved measures of total tissue oxygen saturation. | Change from pre-intervention baseline to 2 hours post-intervention / 2 hours of sitting |
| Normalized haemoglobin index (nTHI) of the gastrocnemius skeletal muscle | Normalized haemoglobin index (relative value of total haemoglobin normalised to the initial value, nTHI) content (a.u.) will be assessed by functional Near-Infrared Spectroscopy (fNIRS) on the medial head of the gastrocnemius muscle during 5 minutes of superficial femoral arterial occlusion and 5 minutes of post-occlusion (reactive hyperaemia). | Change from pre-intervention baseline to 2 hours post-intervention/2 hours sitting |
| Tissue oxygenation index (TOI) of Gastrocnemius skeletal muscle during 2 hours of sitting | Tissue Oxygenation Index (percent TOI) will be assessed by functional Near-Infrared Spectroscopy (fNIRS) on the medial head of the gastrocnemius muscle continuously during 2 hours of sitting. The NIRS device measures changes in chromophore concentrations of oxyhaemoglobin (O2Hb) and deoxyhaemoglobin (HHb), providing depth-resolved measures of total tissue oxygen saturation. Post-intervention time points considered during sitting were 0 minutes , 10 minutes, 60 minutes, and 120 minutes. For each time point, data were averaged over a 60-second period. | Post-intervention time points considered during sitting were 0 , 10 , 60 and 120 minutes. |
| Normalized haemoglobin index (nTHI) of Gastrocnemius skeletal muscle during 2 hours of sitting | Normalized haemoglobin index (relative value of total haemoglobin normalised to the initial value, nTHI) content (a.u.) will be assessed by functional Near-Infrared Spectroscopy (fNIRS) on the medial head of the gastrocnemius muscle continuously during 2 hours of sitting. Post-intervention time points considered during sitting were 0 min , 10 min, 60 min, and 120 min. For each time point, data were averaged over a 60-second period. | Post-intervention time points considered during sitting were 0 min , 10 min, 60 min and 120 min. |
| Brachial Systolic Blood Pressure (SBP) | Resting systolic blood pressure (mmHg) will be measured using an automated oscillometric blood pressure monitor, with a cuff attached to the right upper arm, following at least 10 minutes rest. | Change from pre-intervention baseline to 2 hours post-intervention / 2 hours of sitting |
| Brachial Diastolic Blood Pressure (DBP) | Resting diastolic blood pressure (mmHg) will be measured using an automated oscillometric blood pressure monitor, with a cuff attached to the right upper arm, following at least 10 minutes rest. | Change from pre-intervention baseline to 2 hours post-intervention / 2 hours of sitting |
| Heart Rate | Resting Heart Rate (beats per minute) will be measured using an automated oscillometric blood pressure monitor, with a cuff attached to the right upper arm, following at least 10 minutes rest. | Change from pre-intervention baseline to 2 hours post-intervention/2 hours sitting |
| Resting Superficial Femoral Artery Blood Flow | Superficial Femoral Artery Blood Flow velocity (ml min-1) will be measured using Doppler ultrasonography (uSmart 3300, Terason) interfaced with the Quipu analysis software. Superficial femoral artery blood flow is calculated using Superficial femoral artery blood velocity and diameter during 1 minute of recording in a resting state | Change from pre-intervention baseline to 2 hours post-intervention/2 hours sitting |
| Resting Brachial Artery Blood Flow | Resting Brachial Artery Blood Flow velocity (ml min-1) will be measured using Doppler ultrasonography (uSmart 3300, Terason) interfaced with the Quipu analysis software. Brachial Artery blood flow is calculated using brachial artery blood velocity and diameter during1 minute of recording in a resting state | Change from pre-intervention baseline to 2 hours post-intervention/2 hours sitting |
| Superficial Femoral Artery Shear Rate | Superficial Femoral Artery Shear Rate shear rate (s-1) will be measured using Doppler ultrasonography (uSmart 3300, Terason) interfaced with the Quipu analysis software, during 1 minute in the resting state | Change from pre-intervention baseline to 2 hours post-intervention/2 hours sitting |
| Brachial Artery Shear Rate | Brachial Artery Shear Rate shear rate (s-1) will be measured using Doppler ultrasonography (uSmart 3300, Terason) interfaced with the Quipu analysis software, during 1 minute in the resting state | Change from pre-intervention baseline to 2 hours post-intervention/2 hours sitting |