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Moderate evidencePhysical performance

Stimulant-Free Pre-Workout

Caffeine-free pump formulas built on citrulline and nitrate sources. Both ingredients have meta-analytic support for small performance gains, but the effects are far smaller than caffeine's and the finished blends are untested.

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What the science says

  • Citrulline malate adds a small number of repetitions Moderate evidence

    A systematic review and meta-analysis of randomized trials found citrulline malate produced a small increase in repetitions performed during resistance training. A separate meta-analysis found modest effects on perceived exertion and muscle soreness.

  • Dietary nitrate improves aerobic and sprint performance modestly Moderate evidence

    Meta-analyses of beetroot juice supplementation report small improvements in aerobic and anaerobic performance measures. Effects are most reliable in recreationally trained rather than elite athletes.

  • 'Pump' is not a performance outcome Limited evidence

    Increased blood flow and muscle fullness are what these products are usually marketed on, and they are not established to improve strength or hypertrophy. No trial has tested a commercial stimulant-free pre-workout as a finished formula.

Dosage & safety

Studied doseStudied doses are 6–8 g of citrulline malate about 60 minutes before training, or 300–600 mg of nitrate (roughly 70–140 ml of concentrated beetroot juice) 2–3 hours before. Check that the blend actually reaches these amounts rather than hiding them in a proprietary mix.
SafetyGenerally well tolerated; citrulline at high doses can cause stomach upset, and beetroot turns urine and stools red. Nitrate sources can lower blood pressure, which matters if you take antihypertensives or nitrates for angina — avoid combining with PDE5 inhibitors. Antibacterial mouthwash blunts the nitrate effect.

How to take it

TimingCitrulline about 60 minutes before training; nitrate needs 2–3 hours to peak, so it is not a last-minute scoop.
With food?Either way, though a light meal reduces the stomach upset citrulline can cause at 8 g.
Worth knowingSkip antibacterial mouthwash on training days — it kills the oral bacteria that convert nitrate to nitrite and cancels most of the effect.

Interactions

With medications

  • PDE5 inhibitors such as sildenafil and tadalafil

    Nitrate plus a PDE5 inhibitor can cause a dangerous drop in blood pressure. do not combine

  • nitrates for angina

    Additive vasodilation and hypotension. do not combine without medical supervision

  • antihypertensives

    Dietary nitrate lowers blood pressure on top of the medication. check your readings when starting and tell your doctor

With other supplements

  • beetroot, arginine and other nitric-oxide products

    Stacking several vasodilators compounds the blood-pressure drop and the light-headedness. use one at a time

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Do stimulant-free pre-workouts work?

Stimulant-free pre-workouts rely on citrulline and nitrate, both of which have moderate meta-analytic support for small performance gains, far smaller than caffeine's. No trial has tested a commercial stimulant-free pre-workout as a finished formula, and the 'pump' it is sold on is not an established performance outcome.

How much citrulline malate should a pre-workout have?

Studied doses are 6–8 g of citrulline malate about 60 minutes before training, which added a small number of repetitions in a meta-analysis. For nitrate, 300–600 mg (roughly 70–140 ml of concentrated beetroot juice) 2–3 hours before; check that a stimulant-free pre-workout actually reaches these amounts.

Is a stim-free pre-workout safe with blood pressure pills or Viagra?

Do not combine the nitrate in stimulant-free pre-workouts with PDE5 inhibitors such as sildenafil or tadalafil, or with nitrates for angina, because blood pressure can drop dangerously. If you take antihypertensives, check your readings when starting.

Does mouthwash cancel out a beetroot or nitrate pre-workout?

Yes, antibacterial mouthwash kills the oral bacteria that convert nitrate to nitrite, cancelling most of the effect of a nitrate-based stimulant-free pre-workout. Skip it on training days; beetroot also harmlessly turns urine and stools red.

Scientific references

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