Effects of Coffee Versus Hibiscus Tea Consumption During Prolonged Sitting on Blood Pressure and Heart Rate

August 28, 2025 updated by: Abdullah Bandar Alansare, King Saud University

Modern lifestyles often involve long periods of sitting, which can increase the risk of heart problems, obesity, and other health issues. Diet also plays a key role in heart health. Coffee and hibiscus tea are two common beverages, but their effects during prolonged sitting are not well understood.

This study will examine how drinking coffee versus hibiscus tea affects blood pressure, heart rate, and heart rate variability in men and women during extended periods of sitting.

Participants (30 in total: 15 women and 15 men) will take part in a randomized crossover study, meaning each person will try both beverages at different times. Data will be collected using questionnaires, body measurements, and devices to measure heart rate, blood pressure, and heart rate variability.

The goal is to better understand how these drinks influence heart health during sedentary behavior.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Modern lifestyles, shaped by technological advancements and urbanization, have led to a dramatic increase in sedentary behavior, particularly prolonged sitting. Physical inactivity is a major risk factor for cardiovascular diseases (CVDs), obesity, and premature mortality, with women generally being less active than men. Prolonged sitting affects key indicators of cardiovascular health, including blood pressure, heart rate, and heart rate variability (HRV), which reflect autonomic nervous system regulation and overall heart function. Despite the growing concern, research on how sedentary behavior specifically affects women, particularly in Saudi Arabia, remains limited.

Dietary habits also play a critical role in cardiovascular health. Coffee, one of the most widely consumed beverages worldwide, contains caffeine and polyphenols that can both stimulate and protect the cardiovascular system. Moderate coffee consumption may provide benefits such as reduced risk of chronic diseases and lower resting heart rate, while excessive intake can increase blood pressure, particularly in hypertensive individuals. Hibiscus tea, rich in flavonoids and antioxidants like anthocyanins, has been traditionally used as an antihypertensive agent. It has potential therapeutic effects, including lowering blood pressure, improving metabolic health, and protecting against cardiovascular inflammation. However, the acute effects of these beverages during prolonged sitting are not well understood.

This study aims to investigate the effects of coffee versus hibiscus tea on blood pressure, heart rate, and HRV in healthy women during extended periods of sitting. Using a randomized crossover design, participants will consume each beverage at separate times while their cardiovascular responses are monitored. Data will be collected through questionnaires, body composition measurements, and non-invasive devices to track blood pressure and heart rate variability. By comparing the acute effects of coffee and hibiscus tea during sedentary behavior, this study seeks to provide new insights into how common dietary choices may influence cardiovascular function and help guide recommendations for healthier lifestyles in populations at risk of prolonged sitting.

Study Type

Interventional

Enrollment (Estimated)

30

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact Backup

Study Locations

  • Saudi Arabia
      • Riyadh, Saudi Arabia, 80200
        • Princess Nourah University Lifestyle Center
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Age between 18 and 35 years.
  • Normal to elevated blood pressure (systolic <130 mmHg and diastolic <80 mmHg) and normal resting heart rate (60-100 bpm), ensuring selection of healthy adults and minimizing confounding factors.
  • Generally healthy, without chronic or acute medical conditions, to reduce external influences on study outcomes.
  • Physically inactive, not meeting current physical activity guidelines, as the study targets sedentary individuals.

Exclusion Criteria:

  • Known allergy or hypersensitivity to hibiscus or coffee, as participants will consume these beverages during the study.
  • Current use of medications that could influence blood pressure, heart rate, or heart rate variability, including antihypertensive, chronotropic, or vasoactive drugs.
  • Any medical condition or health issue that may interfere with safe participation or affect study measurements.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Coffee plus prolonged sitting protocol
all participants in this group follow the coffee protocol
Dietary supplement: Coffee
Participants will consume 3 cups of Arabica coffee (Guatemalan origin), providing a total of 400 mg of caffeine. Each cup is prepared with 6% coffee grounds per 100 mL of water, brewed at 90°C for 6 minutes using an electric drip coffee maker, yielding 100.8 mg caffeine per 100 mL. Immediately following coffee consumption, participants will engage in uninterrupted sitting for 3 hours. Blood pressure, heart rate, and other study questionnaires will be measured at baseline (before coffee), 1 hour after coffee intake, and hourly during the 3-hour sitting period.
Experimental: Hibiscus drink plus prolonged sitting protocol
all participants in this group follow the hibiscus drink protocol
Dietary supplement: Hibiscus drink
Participants will consume 3 servings of hibiscus leaves tea per day, each serving containing 1.25 g of dried hibiscus leaves, totaling 3.75 g per session. The tea will be prepared by steeping the leaves in 240 mL of boiling water (100°C) for 10 minutes. Immediately after consuming the hibiscus tea, participants will engage in uninterrupted sitting for 3 hours. Blood pressure, heart rate, and other study questionnaires will be measured at baseline (before tea), 1 hour after tea intake, and hourly during the 3-hour sitting.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Systolic and diastolic blood pressure
Time Frame: Blood pressure will be recorded at five standardized time points: prior to consumption of coffee or hibiscus tea, one hour post-consumption, and following one, two, and three hours of prolonged sitting.
Systolic and diastolic blood pressure will be assessed using an oscillometric blood pressure monitor (Omron HEM 7124 CP, Omron Healthcare, Illinois, USA). Measurements will be conducted in accordance with the guidelines of the American Heart Association (AHA) and the American College of Cardiology (ACC).
Blood pressure will be recorded at five standardized time points: prior to consumption of coffee or hibiscus tea, one hour post-consumption, and following one, two, and three hours of prolonged sitting.
Heart Rate
Time Frame: Heart rate measurements will be performed at multiple time points during each visit: prior to beverage consumption, one hour post-consumption, and after one, two, and three hours of prolonged sitting.

Heart rate will be measured using the Polar V800 system, which consists of a wristwatch and a Bluetooth heart rate sensor. The sensor will be positioned on the participant's chest, just below the pectoral muscles. Participants will remain seated quietly for 10 minutes while continuous heart rate data are recorded according to the manufacturer's instructions.

The clearest five-minute segment of the 10-minute recording will be analyzed using Kubios HRV Premium software to assess heart rate (beat/minute)
Heart rate measurements will be performed at multiple time points during each visit: prior to beverage consumption, one hour post-consumption, and after one, two, and three hours of prolonged sitting.
NN Intervals
Time Frame: NN Intervals measurements will be performed at multiple time points during each visit: prior to beverage consumption, one hour post-consumption, and after one, two, and three hours of prolonged sitting.

NN Intervals will be measured using the Polar V800 system, which consists of a wristwatch and a Bluetooth heart rate sensor. The sensor will be positioned on the participant's chest, just below the pectoral muscles. Participants will remain seated quietly for 10 minutes while continuous heart rate data are recorded according to the manufacturer's instructions.

The clearest five-minute segment of the 10-minute recording will be analyzed using Kubios HRV Premium software to assess NN Intervals (milliseconds)
NN Intervals measurements will be performed at multiple time points during each visit: prior to beverage consumption, one hour post-consumption, and after one, two, and three hours of prolonged sitting.
RMSSD
Time Frame: RMSSD measurements will be performed at multiple time points during each visit: prior to beverage consumption, one hour post-consumption, and after one, two, and three hours of prolonged sitting.

RMSSD will be measured using the Polar V800 system, which consists of a wristwatch and a Bluetooth heart rate sensor. The sensor will be positioned on the participant's chest, just below the pectoral muscles. Participants will remain seated quietly for 10 minutes while continuous heart rate data are recorded according to the manufacturer's instructions.

The clearest five-minute segment of the 10-minute recording will be analyzed using Kubios HRV Premium software to assess RMSSD (milliseconds squared)
RMSSD measurements will be performed at multiple time points during each visit: prior to beverage consumption, one hour post-consumption, and after one, two, and three hours of prolonged sitting.

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Height
Time Frame: One time at baseline

Height (cm) will be measured using an electronic stadiometer (Stadium Scale) with participants standing barefoot in an upright position.

Measurements will be performed under standardized conditions, with participants wearing light clothing and no shoes, to ensure accuracy and consistency.
One time at baseline
Weight
Time Frame: One time at baseline

Body weight (kg) will be recorded using a calibrated digital scale (Seca).

Measurements will be performed under standardized conditions, with participants wearing light clothing and no shoes, to ensure accuracy and consistency.
One time at baseline
Body Mass Index
Time Frame: One time at baseline

Body mass index (BMI) (kg/m2) will be calculated based on height and weight.

Measurements will be performed under standardized conditions, with participants wearing light clothing and no shoes, to ensure accuracy and consistency.
One time at baseline
Body Fat Percentage
Time Frame: One time at baseline

Body fat percentage (%) will be assessed using a bioelectrical impedance analysis device (Tanita MC-980, Japan).

Measurements will be performed under standardized conditions, with participants wearing light clothing and no shoes, to ensure accuracy and consistency.
One time at baseline
Demographic and Personal Information
Time Frame: One time at baseline
Participant demographic and personal data will be collected using a general information form, which includes age and medical history
One time at baseline
Physical activity status
Time Frame: One time at baseline
Participants will complete the short form of the International Physical Activity Questionnaire (IPAQ). They will report the number of days per week and the average minutes per day they engaged in moderate or vigorous physical activity during the past seven days. These responses will be used to calculate the total minutes per week of moderate-to-vigorous physical activity (MVPA). Participants will then be classified into two groups: those who meet the recommended guideline of at least 150 minutes of MVPA per week, and those who do not meet this guideline (<150 minutes per week).
One time at baseline

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

King Saud University

Collaborators

Princess Nourah bint Abdulrahman University, Riyadh, Saudi Arabia

Investigators

  • Principal Investigator: Hadeel M Almalki, BSc, Princess Nourah Bint Abdulrahman University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

September 1, 2025

Primary Completion (Estimated)

February 1, 2026

Study Completion (Estimated)

March 1, 2026

Study Registration Dates

First Submitted

August 23, 2025

First Submitted That Met QC Criteria

August 28, 2025

First Posted (Estimated)

September 8, 2025

Study Record Updates

Last Update Posted (Estimated)

September 8, 2025

Last Update Submitted That Met QC Criteria

August 28, 2025

Last Verified

August 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • No. E-25-9503

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared outside the research team due to restrictions in the informed consent provided by participants

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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