CaffeineNCT07771556
7-Day Caffeine and Upper-Body Power in Active Women
A study testing Caffeine in people with Caffeine and Exercise, run by Birjand University of Medical Sciences at 1 site in Iran.
Trial summary
This study investigated the effects of a 7-day caffeine supplementation on heart rate variability, cognitive performance, and upper-body anaerobic power in active women. Thirty healthy active women aged 25-30 years participated in this double-blind, placebo-controlled trial. Read more about this study
- Who is it for?
- Ages 18 to 30 years, women onlyHealthy volunteers can take part
- Conditions the study is for
- Caffeine, Exercise, Physical Fitness
- What is being tested?
- Caffeine
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 30 participants
- Where
- 1 siteIran
- Study dates
- 1 Jan 2020to 1 Sep 2020
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 30 years
- Women only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Active women aged 25 to 30 years
- Body mass index (BMI) between 18 and 25 kg/m²
- Physical activity readiness (based on the PAR-Q questionnaire)
- No injuries within the last month
- Non-smoking
- No cold or COVID-19 infection in the past four weeks
Show all 9Show fewer
- No cardiovascular, metabolic, or respiratory infections in the last three months
- Normal blood pressure
- No use of anabolic steroids, central nervous system stimulants, or other sports supplements in the past six months
Who cannot join
- Inability to follow the protocol
- Daily caffeine intake exceeding 300 mg (assessed using an adapted FFQ)
- Consumption of alcohol or intense aerobic activity within 48 hours prior to testing
- Resistance training with weights within 72 hours prior to testing
- Caffeine consumption within 24 hours prior to testing
Trial locations and contacts
1 site in 1 country.
Iran1 site
Faculty of Sport Sciences, University of Birjand
Birjand, South Khorasan Province, 9717434765
About this study
Official title: Seven-Day Caffeine Supplementation Enhances Upper-Body Peak Anaerobic Power Without Altering Cardiac Autonomic Function or Cognitive Performance in Active Women: A Double-Blind, Placebo-Controlled Trial
This study investigated the effects of a 7-day caffeine supplementation on heart rate variability, cognitive performance, and upper-body anaerobic power in active women. Thirty healthy active women aged 25-30 years participated in this double-blind, placebo-controlled trial. Participants were randomly assigned to receive either 5 mg/kg of caffeine or a placebo daily for 7 days. Heart rate variability, cognitive function (measured by the Stroop test), and upper-body anaerobic power (measured by a 20-second Wingate test) were assessed at baseline, 90 minutes after supplementation, and 30 minutes after exercise. The primary outcome was peak anaerobic power. The study aimed to determine whether short-term caffeine habituation enhances exercise performance without altering cardiac autonomic function or cognitive performance.
Read the detailed description
This was a double-blind, placebo-controlled, parallel-group study conducted at the University of Birjand, Iran. Thirty active women (aged 25-30 years, BMI 18-25 kg/m²) were randomly assigned to either a caffeine group (n=15) or a placebo group (n=15). Participants received 5 mg/kg of caffeine powder or placebo (flour) in gelatin capsules daily for 7 days.
Heart rate variability (HRV) parameters including RMSSD (Root Mean Square of Successive Differences), SDNN (Standard Deviation of Normal-to-Normal Intervals), LF (Low-Frequency) power, HF (High-Frequency) power, and LF/HF ratio were measured using a Polar H10 heart rate sensor. Cognitive performance was assessed using the Golden Stroop Test (color-word interference task). Upper-body anaerobic power was measured using a 20-second Wingate test on a cycle ergometer (Monark 891 E) with a workload of 50 g/kg body weight.
Measurements were taken at three time points: baseline (after 10-hour overnight fast), 90 minutes post-ingestion, and 30 minutes post-exercise. The protocol was repeated after 7 days of daily supplementation. Data were analyzed using repeated-measures ANOVA with Bonferroni post-hoc tests. The primary outcome was peak power output (W·kg-¹) during the Wingate test. Secondary outcomes included HRV parameters, cognitive performance scores, and other anaerobic performance indices (mean power, minimum power, fatigue index).
- Conditions
- Caffeine, Exercise, Physical Fitness
- Being tested
- Caffeine, Placebo
- Keywords
- Anaerobic Performance, Upper Body, Heart Rate, Dietary Supplements
- Medical subject headings
- Motor Activity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
CaffeineDietary supplement
5 mg/kg of body weight of caffeine powder in a gelatin capsule, ingested daily for 7 days.
PlaceboDietary supplement
Matching placebo capsule containing flour, ingested daily for 7 days.
| Study group | Role | What they receive |
|---|---|---|
| Caffeine Supplementation | Experimental | 5 mg/kg of body weight of caffeine powder in a gelatin capsule, ingested daily for 7 days. Receives: Dietary Supplement: Caffeine |
| Placebo Supplementation | Placebo comparator | Participants received a matching placebo capsule containing flour, ingested daily for 7 days. Receives: Dietary Supplement: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Upper-Body Peak Anaerobic Power
Peak power output (W·kg-¹) measured during a 20-second upper-body Wingate test on a cycle ergometer (Monark 891 E).
Measured: Measured 90 minutes post-ingestion on Day 1 and Day 7.
Secondary outcomes (7)
Change in Cognitive Performance
Cognitive performance assessed using the Golden Stroop Test (color-word interference task). The score represents the number of correct responses in the third part of the test (incongruent condition) within 45 seconds.
Measured: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in RMSSD
Root mean square of successive differences (ms) measured using a Polar H10 heart rate sensor.
Measured: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in SDNN
Standard deviation of normal-to-normal intervals (ms) measured using a Polar H10 heart rate sensor.
Measured: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in LF Power
Low-frequency power (ms²) measured using a Polar H10 heart rate sensor.
Measured: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in HF Power
High-frequency power (ms²) measured using a Polar H10 heart rate sensor.
Measured: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in LF/HF Ratio
Ratio of low-frequency to high-frequency power (dimensionless) measured using a Polar H10 heart rate sensor.
Measured: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in Total Power (TP)
Total power (ms²) measured using a Polar H10 heart rate sensor.
Measured: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Aug 2026
- Study start1 Jan 2020
- Primary completion1 Jul 2020
- Study completion1 Sep 2020
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for CaffeineStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 30 participants (actual)
Sponsor and investigators
- Lead sponsor
- Birjand University of Medical Sciences
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Mohsen mohammadnia ahmadi, Birjand University of Medical Sciences
- Investigators
- Mohsen Ahmadi Mohammadnia, PhD, Principal investigator, university of birjand
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07771556
- Sponsor's protocol ID
- IR.BIRJAND.REC.1401.013
- Status last verified
- Aug 2026
- First submitted
- 10 Aug 2026
- Last updated
- 18 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 18 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Seven-Day Caffeine Supplementation Enhances Upper-Body Peak Anaerobic Power Without Altering Cardiac Autonomic Function or Cognitive Performance in Active Women: A Double-Blind, Placebo-Controlled Trial
- ClinicalTrials.gov ID
- NCT07771556
- Acronym / sponsor ID
- IR.BIRJAND.REC.1401.013
- Conditions
- Caffeine, Exercise, Physical Fitness
- Keywords
- Anaerobic Performance, Upper Body, Heart Rate, Dietary Supplements
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 30 participants (actual)
- Lead sponsor
- Birjand University of Medical SciencesUniversity, hospital or other
- Study start
- 1 Jan 2020 (actual)
- Primary completion
- 1 Jul 2020 (actual)
- Study completion
- 1 Sep 2020 (actual)
- First posted
- 18 Aug 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study investigated the effects of a 7-day caffeine supplementation on heart rate variability, cognitive performance, and upper-body anaerobic power in active women. Thirty healthy active women aged 25-30 years participated in this double-blind, placebo-controlled trial. Participants were randomly assigned to receive either 5 mg/kg of caffeine or a placebo daily for 7 days. Heart rate variability, cognitive function (measured by the Stroop test), and upper-body anaerobic power (measured by a 20-second Wingate test) were assessed at baseline, 90 minutes after supplementation, and 30 minutes after exercise. The primary outcome was peak anaerobic power. The study aimed to determine whether short-term caffeine habituation enhances exercise performance without altering cardiac autonomic function or cognitive performance.
Detailed description
This was a double-blind, placebo-controlled, parallel-group study conducted at the University of Birjand, Iran. Thirty active women (aged 25-30 years, BMI 18-25 kg/m²) were randomly assigned to either a caffeine group (n=15) or a placebo group (n=15). Participants received 5 mg/kg of caffeine powder or placebo (flour) in gelatin capsules daily for 7 days.
Heart rate variability (HRV) parameters including RMSSD (Root Mean Square of Successive Differences), SDNN (Standard Deviation of Normal-to-Normal Intervals), LF (Low-Frequency) power, HF (High-Frequency) power, and LF/HF ratio were measured using a Polar H10 heart rate sensor. Cognitive performance was assessed using the Golden Stroop Test (color-word interference task). Upper-body anaerobic power was measured using a 20-second Wingate test on a cycle ergometer (Monark 891 E) with a workload of 50 g/kg body weight.
Measurements were taken at three time points: baseline (after 10-hour overnight fast), 90 minutes post-ingestion, and 30 minutes post-exercise. The protocol was repeated after 7 days of daily supplementation. Data were analyzed using repeated-measures ANOVA with Bonferroni post-hoc tests. The primary outcome was peak power output (W·kg-¹) during the Wingate test. Secondary outcomes included HRV parameters, cognitive performance scores, and other anaerobic performance indices (mean power, minimum power, fatigue index).
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Caffeine Supplementation | Experimental | Dietary Supplement: Caffeine5 mg/kg of body weight of caffeine powder in a gelatin capsule, ingested daily for 7 days. |
| Placebo Supplementation | Placebo comparator | Dietary Supplement: PlaceboParticipants received a matching placebo capsule containing flour, ingested daily for 7 days. |
Who may qualify
- Ages
- 18 to 30 years
- Sex
- Female only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (9 listed)
- Active women aged 25 to 30 years
- Body mass index (BMI) between 18 and 25 kg/m²
- Physical activity readiness (based on the PAR-Q questionnaire)
- No injuries within the last month
- Non-smoking
Key exclusion criteria (5 listed)
- Inability to follow the protocol
- Daily caffeine intake exceeding 300 mg (assessed using an adapted FFQ)
- Consumption of alcohol or intense aerobic activity within 48 hours prior to testing
- Resistance training with weights within 72 hours prior to testing
- Caffeine consumption within 24 hours prior to testing
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Caffeine5 mg/kg of body weight of caffeine powder in a gelatin capsule, ingested daily for 7 days. | Dietary supplement | Caffeine Supplementation |
| PlaceboMatching placebo capsule containing flour, ingested daily for 7 days. | Dietary supplement | Placebo Supplementation |
Primary outcome
Change in Upper-Body Peak Anaerobic Power
Time frame: Measured 90 minutes post-ingestion on Day 1 and Day 7.
Peak power output (W·kg-¹) measured during a 20-second upper-body Wingate test on a cycle ergometer (Monark 891 E).
7 secondary outcomes
Change in Cognitive Performance
Time frame: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in RMSSD
Time frame: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in SDNN
Time frame: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in LF Power
Time frame: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in HF Power
Time frame: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in LF/HF Ratio
Time frame: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Change in Total Power (TP)
Time frame: Measured at baseline, 90 minutes post-ingestion, and 30 minutes post-exercise on Day 1 and Day 7.
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 18 Aug 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Mohsen Ahmadi Mohammadnia, PhD principal investigator
university of birjand
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Caffeine in people with Caffeine and Exercise, run by Birjand University of Medical Sciences at 1 site in Iran.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 9 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 18 Aug 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Iran. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Upper-Body Peak Anaerobic Power (time frame: Measured 90 minutes post-ingestion on Day 1 and Day 7.). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 Aug 2026.