Supplementation During Endurance PerformanceNCT07853066
Pre-workout Supplement, Arrhythmias and Exercise Stress Test
A study testing Dietary Supplement in people with Supplementation During Endurance Performance, run by University of Sao Paulo at 1 site in Brazil.
Trial summary
Pre-workout supplements are widely used by physically active individuals to enhance exercise performance. These products typically contain stimulant substances such as caffeine, beta-alanine, arginine, and tyrosine, which act on the cardiovascular and central nervous systems. Read more about this study
- Who is it for?
- Ages 18 to 35 yearsHealthy volunteers can take part
- Conditions the study is for
- Supplementation During Endurance Performance
- What is being tested?
- Dietary Supplement
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 62 participants
- Where
- 1 siteBrazil
- Study dates
- 3 Mar 2026to 3 Sep 2026
- 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 35 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Age 18 to 30 years Both sexes Physically active, defined as engaging in at least 150 minutes of moderate-intensity physical activity or 75 minutes of vigorous-intensity physical activity per week, assessed by the International Physical Activity Questionnaire (IPAQ) Prior experience with pre-workout supplements (at least one previous use of any stimulant-based pre-workout supplement) No cardiac arrhythmias identified during the familiarization exercise stress test (Day 1)
Who cannot join
- Presence of cardiac arrhythmias identified during the familiarization exercise stress test (Day 1) Physical inactivity (below the minimum physical activity thresholds on IPAQ) No prior use of any pre-workout or stimulant supplement Use of medications that may interfere with cardiovascular responses to exercise or supplementation Presence of known cardiovascular, metabolic, or musculoskeletal conditions that contraindicate exercise testing Orthopaedic limitations precluding treadmill exercise
Trial locations and contacts
1 site in 1 country.
About this study
Official title: Can a Pre-workout Supplement Cause Arrhythmias During Physical Exercise in Young Physically Active Individuals? A Randomized, Double-blind, Placebo-controlled Study
Pre-workout supplements are widely used by physically active individuals to enhance exercise performance. These products typically contain stimulant substances such as caffeine, beta-alanine, arginine, and tyrosine, which act on the cardiovascular and central nervous systems. Although their ergogenic effects are well established, their safety profile - particularly regarding cardiac arrhythmias during exercise - has not been thoroughly investigated.
This study aimed to evaluate whether the acute ingestion of a commercially available multi-ingredient pre-workout supplement (V-FORT® ULTRA, Vitafor, Brazil) could trigger cardiac arrhythmias during a treadmill exercise stress test in young, physically active adults. A randomized, double-blind, placebo-controlled crossover design was used. Participants underwent two exercise stress tests separated by 3 to 10 days: a familiarization test (Day 1) and an intervention test (Day 2), in which they received either the pre-workout supplement or a placebo beverage. Neither the participants nor the research team conducting the test were aware of the allocated intervention until after test completion.
Read the detailed description
Participants were recruited via social media and screened for eligibility using the International Physical Activity Questionnaire (IPAQ). Only individuals meeting the criteria for physical activity (≥150 minutes/week of moderate-intensity or ≥75 minutes/week of vigorous-intensity exercise) and with prior experience using pre-workout supplements were enrolled.
On Day 1, all participants underwent a familiarization treadmill exercise stress test. Those presenting cardiac arrhythmias at baseline were excluded from the study.
On Day 2 (3 to 10 days later), participants were randomized in a 1:1 ratio to receive either the active supplement (V-FORT® ULTRA: 200 mg caffeine, 2,000 mg beta-alanine, 1,000 mg arginine, 600 mg tyrosine, 300 mg phenylalanine, 415 mg carnitine, vitamins and minerals; 8 kcal per 8 g sachet) or a placebo (Tang® powdered juice: carbohydrates, sodium, vitamin C, and vitamin D; no stimulant substances). The beverage was prepared by the study coordinator in a separate room and consumed by the participant up to 3 hours before the exercise stress test. Both tests were performed at the same time of day for each participant.
The primary outcome was the occurrence of cardiac arrhythmias during the exercise stress test and the 6-minute post-exercise recovery phase, assessed by continuous 12-lead ECG. Secondary outcomes included adverse effects (tachycardia, paraesthesia) and exercise stress test duration.
Statistical analysis included descriptive statistics, normality testing (Shapiro-Wilk), paired comparisons (paired t-test or Wilcoxon signed-rank test for continuous variables; McNemar test for categorical variables), and logistic regression for confounder adjustment. IBM SPSS software was used for all analyses.
- Being tested
- Dietary Supplement, Placebo
- Keywords
- Supplementation during endurance performance
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Dietary SupplementDietary supplement
Single dose of containing 200 mg caffeine, 2,000 mg beta-alanine, 1,000 mg arginine, 600 mg tyrosine, 300 mg phenylalanine, 415 mg carnitine, 1.9 g carbohydrate, vitamins (C, E, B6, B12) and minerals (sodium, magnesium, zinc); 8 kcal per 8 g sachet. Consumed up to 3 hours before the treadmill exercise stress test.
PlaceboDietary supplement
Juice
| Study group | Role | What they receive |
|---|---|---|
| Pre-Workout Supplement | Experimental | Participants received a single dose of V-FORT® ULTRA (Vitafor, Brazil), a multi-ingredient pre-workout supplement containing 200 mg caffeine, 2,000 mg beta-alanine, 1,000 mg arginine, 600 mg tyrosine, 300 mg phenylalanine, 415 mg carnitine, 1.9 g carbohydrate, vitamins (C, E, B6, B12) and minerals (sodium, magnesium, zinc); 8 kcal per 8 g sachet. The beverage was consumed up to 3 hours before the treadmill exercise stress test. Receives: Dietary Supplement: Dietary Supplement |
| Placebo | Placebo comparator | Participants received a single dose of Tang® powdered juice (placebo), containing 2.6 g carbohydrate, 2.4 g sugars, 22 mg sodium, 1.1 mg zinc, 23 mg vitamin C, and 2.5 mcg vitamin D, with no stimulant substances. The beverage was prepared to be visually and organoleptically indistinguishable from the active supplement and was consumed up to 3 hours before the treadmill exercise stress test. Receives: Dietary Supplement: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Occurrence of Cardiac Arrhythmias During the Exercise Stress Test
Presence or absence of cardiac arrhythmias identified on continuous 12-lead ECG during the treadmill exercise stress test and the 6-minute post-exercise recovery phase, compared between the pre-workout supplement and placebo conditions.
Measured: During the treadmill exercise stress test and throughout the 6-minute post-exercise recovery phase (approximately 30 to 60 minutes per session, on Day 2)
Secondary outcomes (2)
Haemodynamic Responses During the Exercise Stress Test
Blood pressure (systolic and diastolic) and heart rate measured at rest, at the end of each exercise stage, at peak effort, and during the post-exercise recovery phase (minutes 1, 2, 4, and 6), compared between the pre-workout supplement and placebo conditions.
Measured: At rest, during each stage of the treadmill exercise stress test, at peak effort, and during the 6-minute post-exercise recovery phase on Day 2
Exercise Stress Test Duration
Total duration of the treadmill exercise stress test in minutes, compared between the pre-workout supplement and placebo conditions (Day 2), and between the familiarization test (Day 1) and the intervention test (Day 2) within the same participant.
Measured: Day 1 (familiarization test) and Day 2 (intervention test), separated by 3 to 10 days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted1 Oct 2026
- Study start3 Mar 2026
- Primary completion3 Sep 2026
- Study completion3 Sep 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Supplementation During Endurance PerformanceStudies 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
- Crossover
- Model description
- Each participant completed two treadmill exercise stress tests separated by 3 to 10 days. On Day 1, a familiarization test was performed to assess baseline cardiac rhythm and exclude participants with pre-existing arrhythmias. On Day 2, participants were randomized (1:1) to receive either the pre-workout supplement or placebo, consumed up to 3 hours before the second exercise stress test. Both tests were performed at the same time of day. The sequence of conditions was determined by randomization, and allocation was concealed from both participants and the testing team until after test completion.
- Masking
- Triple blind
- Who is masked
- Participant, Investigator, Outcomes assessor
- Enrolment
- 62 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Sao Paulo
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Pedro Gabriel Senger Braga, University of Sao Paulo
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07853066
- Sponsor's protocol ID
- 8.071.338
- Other IDs
- 92811525.4.0000.0068
- Status last verified
- Oct 2026
- First submitted
- 27 Sep 2026
- Last updated
- 5 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 5 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Can a Pre-workout Supplement Cause Arrhythmias During Physical Exercise in Young Physically Active Individuals? A Randomized, Double-blind, Placebo-controlled Study
- ClinicalTrials.gov ID
- NCT07853066
- Acronym / sponsor ID
- 8.071.338
- Keywords
- Supplementation during endurance performance
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 62 participants (actual)
- Lead sponsor
- University of Sao PauloUniversity, hospital or other
- Study start
- 3 Mar 2026 (actual)
- Primary completion
- 3 Sep 2026 (actual)
- Study completion
- 3 Sep 2026 (actual)
- First posted
- 1 Oct 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.
Pre-workout supplements are widely used by physically active individuals to enhance exercise performance. These products typically contain stimulant substances such as caffeine, beta-alanine, arginine, and tyrosine, which act on the cardiovascular and central nervous systems. Although their ergogenic effects are well established, their safety profile - particularly regarding cardiac arrhythmias during exercise - has not been thoroughly investigated.
This study aimed to evaluate whether the acute ingestion of a commercially available multi-ingredient pre-workout supplement (V-FORT® ULTRA, Vitafor, Brazil) could trigger cardiac arrhythmias during a treadmill exercise stress test in young, physically active adults. A randomized, double-blind, placebo-controlled crossover design was used. Participants underwent two exercise stress tests separated by 3 to 10 days: a familiarization test (Day 1) and an intervention test (Day 2), in which they received either the pre-workout supplement or a placebo beverage. Neither the participants nor the research team conducting the test were aware of the allocated intervention until after test completion.
Detailed description
Participants were recruited via social media and screened for eligibility using the International Physical Activity Questionnaire (IPAQ). Only individuals meeting the criteria for physical activity (≥150 minutes/week of moderate-intensity or ≥75 minutes/week of vigorous-intensity exercise) and with prior experience using pre-workout supplements were enrolled.
On Day 1, all participants underwent a familiarization treadmill exercise stress test. Those presenting cardiac arrhythmias at baseline were excluded from the study.
On Day 2 (3 to 10 days later), participants were randomized in a 1:1 ratio to receive either the active supplement (V-FORT® ULTRA: 200 mg caffeine, 2,000 mg beta-alanine, 1,000 mg arginine, 600 mg tyrosine, 300 mg phenylalanine, 415 mg carnitine, vitamins and minerals; 8 kcal per 8 g sachet) or a placebo (Tang® powdered juice: carbohydrates, sodium, vitamin C, and vitamin D; no stimulant substances). The beverage was prepared by the study coordinator in a separate room and consumed by the participant up to 3 hours before the exercise stress test. Both tests were performed at the same time of day for each participant.
The primary outcome was the occurrence of cardiac arrhythmias during the exercise stress test and the 6-minute post-exercise recovery phase, assessed by continuous 12-lead ECG. Secondary outcomes included adverse effects (tachycardia, paraesthesia) and exercise stress test duration.
Statistical analysis included descriptive statistics, normality testing (Shapiro-Wilk), paired comparisons (paired t-test or Wilcoxon signed-rank test for continuous variables; McNemar test for categorical variables), and logistic regression for confounder adjustment. IBM SPSS software was used for all analyses.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Crossover
- Masking
- Triple blind (participant, investigator, outcomes assessor)
- Number of arms
- 2
- Model description
- Each participant completed two treadmill exercise stress tests separated by 3 to 10 days. On Day 1, a familiarization test was performed to assess baseline cardiac rhythm and exclude participants with pre-existing arrhythmias. On Day 2, participants were randomized (1:1) to receive either the pre-workout supplement or placebo, consumed up to 3 hours before the second exercise stress test. Both tests were performed at the same time of day. The sequence of conditions was determined by randomization, and allocation was concealed from both participants and the testing team until after test completion.
| Arm | Type | Receives |
|---|---|---|
| Pre-Workout Supplement | Experimental | Dietary Supplement: Dietary SupplementParticipants received a single dose of V-FORT® ULTRA (Vitafor, Brazil), a multi-ingredient pre-workout supplement containing 200 mg caffeine, 2,000 mg beta-alanine, 1,000 mg arginine, 600 mg tyrosine, 300 mg phenylalanine, 415 mg carnitine, 1.9 g carbohydrate, vitamins (C, E, B6, B12) and minerals (sodium, magnesium, zinc); 8 kcal per 8 g sachet. The beverage was consumed up to 3 hours before the treadmill exercise stress test. |
| Placebo | Placebo comparator | Dietary Supplement: PlaceboParticipants received a single dose of Tang® powdered juice (placebo), containing 2.6 g carbohydrate, 2.4 g sugars, 22 mg sodium, 1.1 mg zinc, 23 mg vitamin C, and 2.5 mcg vitamin D, with no stimulant substances. The beverage was prepared to be visually and organoleptically indistinguishable from the active supplement and was consumed up to 3 hours before the treadmill exercise stress test. |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (1 listed)
- Age 18 to 30 years Both sexes Physically active, defined as engaging in at least 150 minutes of moderate-intensity physical activity or 75 minutes of vigorous-intensity physical activity per week, assessed by the International Physical Activity Questionnaire (IPAQ) Prior experience with pre-workout supplements (at least one previous use of any stimulant-based pre-workout supplement) No cardiac arrhythmias identified during the familiarization exercise stress test (Day 1)
Key exclusion criteria (1 listed)
- Presence of cardiac arrhythmias identified during the familiarization exercise stress test (Day 1) Physical inactivity (below the minimum physical activity thresholds on IPAQ) No prior use of any pre-workout or stimulant supplement Use of medications that may interfere with cardiovascular responses to exercise or supplementation Presence of known cardiovascular, metabolic, or musculoskeletal conditions that contraindicate exercise testing Orthopaedic limitations precluding treadmill exercise
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 |
|---|---|---|
| Dietary SupplementSingle dose of containing 200 mg caffeine, 2,000 mg beta-alanine, 1,000 mg arginine, 600 mg tyrosine, 300 mg phenylalanine, 415 mg carnitine, 1.9 g carbohydrate, vitamins (C, E, B6, B12) and minerals (sodium, magnesium, zinc); 8 kcal per 8 g sachet. Consumed up to 3 hours before the treadmill exercise stress test. | Dietary supplement | Pre-Workout Supplement |
| PlaceboJuice | Dietary supplement | Placebo |
Primary outcome
Occurrence of Cardiac Arrhythmias During the Exercise Stress Test
Time frame: During the treadmill exercise stress test and throughout the 6-minute post-exercise recovery phase (approximately 30 to 60 minutes per session, on Day 2)
Presence or absence of cardiac arrhythmias identified on continuous 12-lead ECG during the treadmill exercise stress test and the 6-minute post-exercise recovery phase, compared between the pre-workout supplement and placebo conditions.
2 secondary outcomes
Haemodynamic Responses During the Exercise Stress Test
Time frame: At rest, during each stage of the treadmill exercise stress test, at peak effort, and during the 6-minute post-exercise recovery phase on Day 2
Exercise Stress Test Duration
Time frame: Day 1 (familiarization test) and Day 2 (intervention test), separated by 3 to 10 days
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 5 Oct 2026.
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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.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Dietary Supplement in people with Supplementation During Endurance Performance, run by University of Sao Paulo at 1 site in Brazil.
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 1 inclusion and 1 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 5 Oct 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 Brazil. 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?
Occurrence of Cardiac Arrhythmias During the Exercise Stress Test (time frame: During the treadmill exercise stress test and throughout the 6-minute post-exercise recovery phase (approximately 30 to 60 minutes per session, on Day 2)). 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 5 Oct 2026.