I’ve been using pre-workout stuff for a while now — citrulline, creatine, a Liquid IV for hydration, sometimes glycerol for a better pump. Here’s what the science actually supports, what’s overhyped, and a few things I wish someone had told me earlier.
The Quick Reference
| Ingredient | What It Does | Typical Dose | Evidence Strength |
|---|---|---|---|
| Caffeine | Energy, focus, reduced perceived fatigue | 100–200mg | Strong |
| Beta-Alanine | Delays fatigue in high-intensity efforts | 2–5g daily | Strong |
| Citrulline / Citrulline Malate | Blood flow, “pump,” possible endurance | 3–8g | Mixed — newer research is less convincing |
| Nitrate (beetroot) | Improves oxygen efficiency | 300–500mg | Strong, especially for endurance |
| Glycerol | Hyperhydration, fuller pumps | 1g/kg bodyweight | Solid, but purity matters a lot |
Caffeine: Still the Most Reliable One
Caffeine blocks adenosine receptors, which is the main reason it cuts through fatigue and sharpens focus. This is genuinely one of the most well-established performance aids that exists — more so than almost anything else on this list.
Dose: 100–200mg, 30–60 minutes before training. Don’t stack close to your other caffeine intake for the day — total daily caffeine matters, not just your pre-workout dose. Cut it off at least 6 hours before bed if sleep is a priority for you (and it should be — recovery depends on it).
Beta-Alanine: The Tingles Are Normal
Beta-alanine raises carnosine levels in muscle, which helps buffer acid buildup during hard efforts — meaning you can push a little longer before things get unbearable. The tingling sensation (paresthesia) some people get is harmless, just uncomfortable for some.
Dose: 2–5g daily, split into smaller doses to reduce tingling. This one builds up over time — it’s not really an “acute” pre-workout effect, more of a saturation strategy over weeks.
Citrulline Malate: Real, But Overhyped Lately
The original, well-cited study on citrulline malate (Pérez-Guisado & Jakeman, 2010) found a real benefit for reps-to-fatigue. But more recent, better-controlled studies have had much more mixed results — several found no significant difference from placebo for actual strength/rep performance, even though people often report feeling a better pump.
That doesn’t mean it’s useless — the “pump” and blood flow effects are real and well-documented — just don’t expect it to be a guaranteed strength or rep booster the way some marketing suggests.
Dose: 6–8g, 30-60 minutes pre-workout.
Citrulline vs. Citrulline Malate — Which One I Actually Use
I switched to plain L-citrulline over citrulline malate, and here’s the reasoning that holds up:
Citrulline malate is just L-citrulline bonded to malic acid — a compound naturally found in fruit. By weight, citrulline malate is only about 56% actual citrulline. So an 8g dose of citrulline malate is only delivering roughly 4.5g of actual citrulline — the rest is the malate portion.
That matters for a simple reason: if you want a meaningful dose of citrulline itself, you either need more total grams of citrulline malate to get there, or you can just take pure L-citrulline and hit your target dose directly without the extra bulk.
The malate part isn’t nothing — there’s a reasonable theory that malate may support energy production via the Krebs cycle — but here’s the honest state of the research: no study has directly compared equal citrulline doses of the pure form vs. the malate form to see if the malate actually adds a measurable benefit. It’s a plausible mechanism, not a proven one.
What the research does show clearly: pure L-citrulline is well-absorbed and actually raises plasma arginine levels more effectively than taking arginine directly — your body converts it more efficiently that way. So you’re not losing anything by skipping the malate.
| Citrulline Malate | Pure L-Citrulline | |
|---|---|---|
| Citrulline content | ~56% by weight | 100% |
| Typical dose | 6–8g | 3–6g |
| Actual citrulline delivered | ~3.5–4.5g | 3–6g (all of it) |
| Extra ingredient | Malic acid (theoretical energy benefit) | None |
| Why people choose it | Slightly cheaper per gram, marketed benefit of “added energy” | Cleaner dose, no filler, easier to dial in exact citrulline amount |
Bottom line on this one: if you want a precise, higher dose of citrulline without doubling up on malic acid you didn’t ask for, pure L-citrulline is the more direct option. Citrulline malate isn’t wrong, it’s just less citrulline-dense per gram, and the “extra” ingredient’s benefit is still theoretical rather than proven.
Nitric Oxide / Nitrate: Solid for Endurance, Less Proven for Lifting
Beetroot-derived nitrate genuinely improves oxygen efficiency during exercise — this is one of the better-supported “pump” category ingredients, especially for endurance work. Less direct evidence for pure strength training, but it complements citrulline reasonably well.
Dose: 300–500mg beetroot nitrate, or 6-8g L-arginine, 30-60 minutes pre-workout.
Glycerol: Real Hyperhydration Science — Sourcing Matters
Glycerol pulls water into your cells, creating a genuine state of hyperhydration — this is well-studied, particularly for endurance athletes trying to stay hydrated in heat. It’s a legitimate mechanism, not just pump-chasing marketing.
Important: glycerol, glycerin, and glycerine are all the same molecule — don’t let the naming confuse you. What matters is purity. Only use USP or food-grade glycerol (99.5%+ pure) from a reputable, third-party-tested source. Avoid unlabeled or industrial-grade glycerin — poor-quality glycerin has a real history of contamination with toxic industrial byproducts when purity isn’t verified. This is one supplement where cutting corners on sourcing isn’t worth the risk.
Dose: Roughly 1g per kg of bodyweight, mixed with adequate water (glycerol needs fluid to work — it’s not effective taken dry).
How I’d Stack These
| Goal | Combo |
|---|---|
| General training day | Caffeine + creatine |
| Heavy pump day | Citrulline + glycerol + plenty of water |
| Endurance/cardio focus | Nitrate + beta-alanine |
| Hot weather / long session | Glycerol + electrolytes (Liquid IV-style) |
A Few Safety Notes
- Start low. Half doses first to see how your body responds, especially with beta-alanine tingling or caffeine sensitivity.
- Hydrate deliberately, especially with glycerol — it needs water to do its job and can pull fluid unpredictably if you’re not drinking enough alongside it.
- Check for interactions if you’re on blood pressure medication — several of these ingredients affect blood flow and vasodilation.
- Third-party testing matters. NSF Certified for Sport or Informed Choice labeling is worth paying attention to, especially for less-regulated ingredients like glycerol.
Bottom Line
Caffeine and beta-alanine have the strongest science behind them. Nitrate is solid, especially for endurance. Citrulline’s reputation has softened a bit under newer research, though it’s not useless — and if you’re going to use it, pure L-citrulline gets you more actual citrulline per gram than the malate version. Glycerol works — but only if you’re sourcing it carefully. None of this replaces training hard and consistently; it’s all just margin at the edges.
Disclaimer: This isn’t medical advice. Talk to a healthcare provider before starting new supplements, especially if you’re on medication, pregnant, or have cardiovascular or kidney concerns.