Can pre-workout supplements (PWS) cause palpitations during exercise?

Pre-Workout Supplements and Palpitations During Exercise

Yes, pre-workout supplements can cause palpitations during exercise, primarily due to stimulant content—particularly caffeine and other sympathomimetic agents—which should be queried and considered in any athlete presenting with symptomatic palpitations or documented arrhythmias. 1

Primary Mechanism and Causative Agents

The cardiovascular effects of pre-workout supplements stem from their stimulant ingredients:

• Caffeine is the primary culprit, acting as a central nervous system stimulant and adenosine receptor antagonist that can cause tachycardia, arrhythmias, anxiety, and tremors, particularly at high doses 1
• Synephrine, commonly found in pre-workout formulations, has been directly associated with chest pain, palpitations, syncope, cardiac arrhythmias, and ischemic heart disease in case reports 2
• Beta-phenethylamine and other sympathomimetic compounds can cause hypertension, tachycardia, and vasospasm 3
• The 2025 ACC/AHA guidelines explicitly state that stimulant use in dietary and workout beverages should be queried in competitive athletes with hypertension, symptomatic palpitations, or documented ectopy or arrhythmias 1

Clinical Presentation and Documented Adverse Events

Pre-workout supplements have been associated with serious cardiovascular events:

• Most common symptoms: chest pain, palpitations, syncope, and dizziness 2
• Documented cardiac complications: sinus tachycardia, elevated troponin (demand ischemia), cardiac arrhythmias, and in severe cases, hemorrhagic stroke and myocardial infarction 4, 3
• Case reports document that five patients were left disabled or remained on medication following synephrine-containing supplement use 2
• The 2021 UEFA expert group noted that banned stimulants are frequently found in so-called "training or pre-workout boosters" 1

Risk Assessment and Evaluation

When an athlete presents with palpitations during exercise, immediate evaluation is mandatory:

• Obtain detailed supplement history, specifically asking about pre-workout products, energy drinks, and caffeine intake 1
• Perform 12-lead ECG to identify pre-excitation patterns, QT abnormalities, and signs of structural heart disease 5, 6
• Exercise testing should reproduce the level of exertion to assess for exercise-induced arrhythmias 5
• Echocardiography is essential to exclude structural abnormalities including hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy 5, 6
• 48-hour ambulatory monitoring with instructions to perform usual exercise levels captures arrhythmia frequency and patterns 5

Management Algorithm

Immediate actions:

• Discontinue all pre-workout supplements immediately when palpitations are reported 1
• Temporary cessation of competitive sports during evaluation if high-risk features are present 5, 6
• Athletes with isolated premature ventricular complexes that suppress with exercise can participate in all competitive sports once structural disease is excluded 5

Risk stratification:

• PVCs that increase in frequency during exercise or convert to repetitive forms mandate further evaluation before clearance 5
• If PVCs exceed 2,000 per 24 hours, annual cardiological evaluation is required to monitor for PVC-induced cardiomyopathy 5
• Athletes with benign arrhythmias and no structural heart disease can participate in all competitive sports without restriction 5

Critical Pitfalls to Avoid

• Do not dismiss palpitations with exercise as benign without proper cardiac evaluation, as they may represent the initial manifestation of life-threatening conditions 1, 6
• Do not overlook the "proprietary blend" issue: most pre-workout supplements contain undisclosed dosages of multiple stimulants, making it impossible to determine actual exposure 7
• Recognize contamination risk: supplements may contain banned stimulants and other prohibited substances not listed on labels, with historical contamination rates of 15-25% 1
• Consider synergistic effects: caffeine combined with other sympathomimetics in pre-workout formulations may produce more severe cardiovascular effects than caffeine alone 2, 3

Special Considerations

The FDA drug label for caffeine notes cardiovascular effects including tachycardia and increased stroke volume, though this pertains to pharmaceutical-grade caffeine 8. However, pre-workout supplements often contain caffeine in combination with multiple other stimulants at undisclosed doses, substantially increasing risk 1, 2.

Athletes must be educated on the cardiovascular risks of performance-enhancing drugs and supplements, as mandated by the 2025 ACC/AHA guidelines 1. The evidence demonstrates that while some studies show no adverse effects with controlled dosing in research settings 7, real-world use involves variable formulations, excessive dosing, and contamination that create genuine cardiovascular risk 2, 4, 3.