Pre-workout supplements under scanner: Doctor warns of heart strain, anxiety and sleep loss

That upsurge of vitality before a workout put up sense empowering — portion you lift heavier, move faster and train harder. But doctors warn that regular or excessive use of pre-workout supplements may come with hidden health costs, particularly for the heart, mind and sleep cycle.

Dr Kunal Sood, an anaesthesiologist and interventional pain medicine specialist, recently broke down the potential risks of frequent pre-workout use in an Instagram video shared on 13 December. He explained how commonly used ingredients in these supplements can affect cardiovascular health, trigger anxiety, disrupt sleep and, in extreme cases, strain the kidneys.

According to Dr Sood, most pre-workout formulas rely on synthetic stimulants to deliver an instant performance boost. These typically include high doses of caffeine (often between 150mg and 300mg per serving), along with compounds such as synephrine or yohimbine, nitric oxide boosters, beta-alanine and various amino acids.

While these ingredients may improve workout performance, Dr Sood cautioned that they can also interfere with normal heart and blood vessel function, depending on the stimulant load.

Stimulant-heavy blends can cause a rapid rise in heart rate and blood pressure. Dr Sood cited research showing higher systolic and diastolic blood pressure after consuming one or two scoops of pre-workout compared to a placebo. He added that case reports have linked synephrine-containing supplements to serious cardiovascular events, including arrhythmias, reduced blood flow to the heart and, in rare cases, stroke.

High caffeine intake is a known anxiety trigger, and pre-workout supplements can push users into risky territory. Dr Sood noted that anxiety symptoms increase even at moderate caffeine levels and become more pronounced beyond about 400mg. “Many pre-workout scoops already contain 250–300mg of caffeine,” he said, adding that double-scooping or combining supplements with coffee can easily cross anxiety-inducing thresholds.

Taking pre-workout supplements too close to bedtime can significantly interfere with sleep. According to Dr Sood, caffeine can reduce total sleep time, delay sleep onset and lower sleep efficiency. Studies suggest that a typical pre-workout dose may need to be taken more than 13 hours before bedtime to avoid meaningful sleep disruption, with higher doses reducing deep sleep even 8 to 12 hours later.

While occasional use within recommended limits is generally tolerated by healthy individuals, excessive or chronic misuse can be dangerous. Dr Sood highlighted reports of severe muscle breakdown, metabolic disturbances and acute kidney injury linked to heavy pre-workout or concentrated caffeine abuse.

Health experts advise reading labels carefully, avoiding double dosing and being especially cautious if you have underlying heart conditions, anxiety disorders or sleep problems. For many, simpler alternatives — such as adequate sleep, hydration and balanced nutrition — may offer safer, more sustainable workout energy.

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