Your 2 PM Workout Can Seesaw: A New Study Links Energy Drinks to Cardiac Arrest Reports in Young Adults. The can is not a health plan.
By Dakota Jones
Desk: Science, Health & Environment, Health & Medicine (Public Health & Epidemiology)
[ANCHOR] If your afternoon workout comes with an energy drink or a scoop of pre-workout, new research offers a reason to look at the label before you head out. It does not prove those products caused anyone’s heart emergency. That distinction matters. So does the fact that a preliminary study found energy drinks and stimulant-containing supplements appearing disproportionately often in FDA reports of serious cardiovascular events, especially reports involving adults ages 18 to 34.
The research abstract, MDP0323, was released November 2 ahead of the American Heart Association’s Scientific Sessions 2026, scheduled for November 6–9 in Chicago. The headline numbers are striking. The evidence has significant limits. Both facts belong in the same story; one does not cancel the other.
Here’s what the study found, what it cannot tell us, and what you can do with that information without treating an abstract like a verdict.
What the study found, and what “11 times more often” means
[ANCHOR] Researchers reviewed 28,345 reports made to an FDA safety database between 2017 and 2025. The reports concerned people ages 13 or older and possible adverse events linked to products regulated as foods or dietary supplements.
Of the total, 854 reports mentioned energy drinks or dietary supplements containing caffeine or other stimulants. Researchers compared those with 27,491 reports involving products without caffeine or other stimulants.
In the reports, cardiac arrest appeared about 11 times more often in connection with caffeine- and stimulant-containing products than in reports involving products without those ingredients. Reports involving stimulant products were also about 4.5 times more likely to include a heart attack, and four times more likely to include ventricular arrhythmias or heart palpitations.
That wording needs a small but important speed bump. These are comparisons within adverse-event reports. They are not a measurement showing that an individual who drinks an energy drink has 11 times the risk of cardiac arrest. The study did not establish an individual’s odds of having an event after consuming one of these products.
[GRAPHIC: Findings in the reports]
| Cardiovascular event mentioned | Relative reporting in caffeine/stimulant-product reports |
|---|---|
| Cardiac arrest | About 11 times more often |
| Heart attack | About 4.5 times more likely |
| Ventricular arrhythmia or heart palpitations | About 4 times more likely |
| Elevated heart rate | Nearly 3 times more often |
| Chest pain | 2.71 times more often |
| Fainting | About 2 times more often |
The analysis also found that about 45% of reports linking caffeine- or stimulant-containing products to cardiovascular events involved adults ages 18 to 34. Similar patterns appeared in reports involving men and women.
That’s a signal worth examining. It is not a head count of everyone who used these products, and it is not proof that the products caused the events.
The product label matters more than the brand name
[ANCHOR] This study grouped products by ingredients, not by brand. So the findings do not single out a particular can, tub, or logo. They concern products containing caffeine or other stimulants.
The researchers counted caffeine, methylxanthines and sympathomimetics. Methylxanthines include theobromine and ingredients such as guarana, yerba mate, and green tea or coffee extracts. The sympathomimetic category includes synephrine, yohimbine, ephedra, DMAA, and higenamine.
That ingredient list matters because “energy drink” and “pre-workout” can cover a wide range of formulas. The word energy on a package does not tell you how much caffeine is in a serving, what else is in the blend, or how much caffeine you’ve already had that day.
The American Heart Association’s 2026 scientific statement says up to 400 milligrams of caffeine per day, equivalent to up to five 8-ounce cups of black coffee, is generally safe for most adults. That is general guidance, not a personalized target or a guarantee that a specific product is right for you.
The AHA also notes that some energy drinks contain as much as three times more caffeine per fluid ounce than brewed coffee, while some pre-workout supplements contain more than 12 times as much per fluid ounce. Per-ounce comparisons do not tell you the caffeine in the whole serving by themselves. You still need to check the serving size and total amount.
[GRAPHIC: Caffeine context]
- Up to 400 mg per day: Generally considered safe for most adults, according to the AHA’s 2026 statement.
- Some energy drinks: Up to 3 times more caffeine per fluid ounce than brewed coffee.
- Some pre-workout supplements: More than 12 times as much caffeine per fluid ounce as brewed coffee.
And there is a regulatory wrinkle. Energy drinks and stimulant supplements are regulated by the FDA as foods or dietary supplements, not medications. They do not go through the same premarket safety testing required for medications. The market is not small, either: sales of caffeinated energy drinks more than doubled over the past decade, reaching over $20 billion in 2024.
The label is therefore doing a lot of work. You should make it do some work for you, too.
Why the young-adult pattern is not a settled explanation
[ANCHOR] The concentration of reports involving younger adults is concerning. The researchers say they do not yet fully understand why the pattern is so pronounced.
Possible explanations include how often young adults consume these products, when they consume them, and what else is involved. The study authors point to use before intense exercise, mixing with alcohol or drugs, and undiagnosed heart conditions as possibilities. Those are potential explanations, not findings that the study proved.
The title’s 2 p.m. workout is a familiar setup, not a result from this research. The study does not show that exercising at 2 p.m. is dangerous. It does not establish that taking a particular product before a workout causes a cardiac event. It cannot tell us whether timing, dose, another substance, an existing condition, or some combination was involved in any specific report.
That gap is not a reason to panic. It is a reason to avoid turning a report-based association into a causal claim.
Study author Sai Samayamanthula, a fourth-year medical student at the University of Virginia School of Medicine in Charlottesville, said these products are marketed as everyday pick-me-ups and sold next to soda and bottled water. In other words, they can look routine. He said occasional use is probably low risk for healthy people, while regular consumers can quickly exceed recommended daily caffeine limits.
That is a measured statement, not a blanket safety clearance. “Probably low risk” is not “risk-free,” and the study does not define an individual safe dose for every product or person.
The caveats are not fine print
[ANCHOR] This is a preliminary analysis of voluntarily self-reported adverse events. People, clinicians, manufacturers and others can report a suspected problem to the FDA. A report does not, on its own, confirm that a product caused the event.
There are two missing denominators that make a world of difference. Researchers do not know how many people consumed these products without experiencing a cardiac event. They also do not know how many people experienced an event but never reported it. Without those counts, the reports cannot show the absolute risk among all consumers.
And there is another caution: abstracts presented at AHA scientific meetings are not peer-reviewed. The findings are preliminary until published as a full manuscript in a peer-reviewed journal. The research was scheduled for presentation at the November 6–9 meeting in Chicago; the abstract was released ahead of it on November 2.
Dr. Gregory M. Marcus of the University of California, San Francisco, chair of the AHA’s 2026 scientific statement on caffeine and cardiovascular disease and not involved in this study, said the findings raise concerns about products with very high caffeine amounts. He also emphasized that the study does not prove those products caused the reported events and that more research is needed.
That’s the cleanest summary: a concerning association in a voluntary reporting database; not proof of causation, not a population-wide risk estimate, and not yet peer-reviewed research.
What you can do with the evidence today
[ANCHOR] You do not need to treat every can as a medical emergency. You also do not need to treat a product sold beside bottled water as automatically harmless. A few practical steps are sensible while the research develops:
- Check the serving and caffeine amount. Read the full label, including serving size. A container may include more than one serving, and caffeine can come from multiple ingredients.
- Count all sources together. Coffee, tea, energy drinks, supplements and other caffeine-containing products all contribute to your daily total.
- Look beyond caffeine. Check for other stimulant ingredients, especially if you use more than one supplement or product.
- Be cautious about combinations. The researchers specifically identify intense exercise, alcohol or drugs as possible factors that warrant further study. The report does not quantify the risk of any particular combination.
- Tell your clinician what you take. Samayamanthula recommends that healthcare professionals ask younger patients reporting palpitations, chest pain or fainting whether they recently or regularly use energy drinks or stimulant supplements.
- Get medical advice about concerning symptoms. Palpitations, chest pain or fainting deserve attention; do not assume a supplement is, or is not, the explanation.
That list is not a substitute for individualized medical advice. It is a way to make the product information visible, rather than hoping the word “energy” has already handled the safety review.
FAQ: Energy drinks and the preliminary study
Does this study prove energy drinks cause cardiac arrest?
No. It found an association in voluntarily reported adverse-event records. It cannot establish that the products caused the events.
Does “11 times more often” mean my risk is 11 times higher?
No. The figure describes how often cardiac arrest appeared in one group of reports compared with another. It is not an estimate of an individual consumer’s risk.
Were specific brands identified?
No. Products were grouped by ingredients, not by brand.
Is the research peer-reviewed?
Not at this stage. The findings come from a preliminary abstract. AHA meeting abstracts are not peer-reviewed, and results remain preliminary until published in a peer-reviewed journal.
What does the AHA say about daily caffeine?
The AHA’s 2026 statement says up to 400 mg per day is generally safe for most adults. That general guidance does not mean every product, serving, or combination is suitable for every person.
Final thoughts: Read the label, keep the uncertainty honest
[ANCHOR] This study is not a reason to announce that energy drinks caused a wave of cardiac arrests. It is a reason to take a notable safety signal seriously, improve systematic monitoring, and ask better questions, especially when a younger patient reports palpitations, chest pain or fainting.
The findings are preliminary and based on voluntary reports. We do not know the number of consumers who had no event, or the number of events that were never reported. We do know that serious cardiovascular events appeared disproportionately often in reports involving caffeine- and stimulant-containing products, and that adults ages 18 to 34 accounted for about 45% of the reports linking those products to cardiovascular events.
So keep the verdict precise: association, not causation. Check the ingredients. Track your total caffeine. Tell your clinician what you use. And let future peer-reviewed research do the job of turning an early signal into firmer evidence.
For more reporting from our Science, Health & Environment desk, visit LD3 Productions’ science and health coverage.
Sources
- American Heart Association newsroom release, November 2, 2026: primary source for the abstract details and study limitations.
- NBC News, November 2, 2026: independent confirmation of the study and headline finding.