By MeridianMedicalCentre.com Health Research Team
“Pre-workout” is a label, not an ingredient. Depending on the product, it might contain caffeine, creatine, beta-alanine, citrulline, beetroot extract, branched-chain amino acids (BCAAs), or some combination of all of them — and the research evidence behind each one is different, both in strength and in what kind of exercise it actually helps with. This guide walks through what the National Institutes of Health's Office of Dietary Supplements (ODS) says the evidence shows for the most common pre-workout ingredients, what a “proprietary blend” on a label does and doesn't tell you, and a short worksheet you can use to sort through a product before deciding whether you need one at all.
Which Ingredients Have Evidence — and for What
According to ODS, the research on performance supplements is ingredient-specific: what works for a sprint doesn't necessarily work for a long run, and most ingredient combinations (as opposed to single ingredients) haven't been studied at all. Here's what the evidence shows for the ingredients most commonly found in pre-workout products:
- Caffeine — The most consistently supported ingredient on this list. Research suggests it can help with endurance activity (distance running) and sports requiring intense, intermittent effort (soccer, tennis), but it does not appear to help with short, maximal-effort activity like sprinting or a single heavy weightlifting set. The amount used in research is 2 to 6 milligrams per kilogram of body weight, taken 15 to 60 minutes before exercise — for reference, a cup of coffee has roughly 85 to 100 mg. Intakes above 500 mg a day have been linked to reduced performance, disrupted sleep, and anxiety, and people respond to caffeine differently, so it doesn't boost performance in everyone.
- Creatine — Supported for short, intense, repeated bursts of effort lasting up to roughly 2.5 minutes at a time, such as sprinting or weightlifting. It has little demonstrated value for endurance activity like distance running or cycling. Research protocols typically use a loading phase (around 20 grams a day, split into four doses, for 5 to 7 days) followed by a lower maintenance amount (3 to 5 grams a day). It's generally considered safe for healthy adults over weeks or months, though it commonly causes some water-retention weight gain.
- Beta-alanine — Some, though not all, studies show small improvements in high-intensity, intermittent activity (swimming, hockey, football-style sports). It isn't clear whether it helps steadier endurance activity like cycling. A known side effect at amounts of 800 mg or more is paresthesia — a temporary tingling or prickling sensation in the face, neck, or hands — which isn't considered harmful but can be uncomfortable.
- Citrulline — The research here is limited and mixed; some studies show a small benefit, some show none, and a few show a possible negative effect. ODS doesn't consider the evidence strong enough yet to support a performance claim either way.
- Beetroot or beet juice (nitrate) — Many, though not all, studies show a benefit for aerobic endurance activity (running, swimming, cycling, rowing) in recreationally active people; the effect is less clear in highly trained athletes, and it isn't established that beetroot powder (as opposed to juice, which is what most studies used) produces the same effect.
- Branched-chain amino acids (BCAAs) — Limited evidence for endurance performance. They may support muscle size and strength when combined with a weight-training program, but ODS notes it isn't clear that BCAA supplements add anything beyond what eating enough dietary protein already provides.
What a Proprietary Blend Doesn't Tell You
A number of pre-workout products list some of their ingredients inside a “proprietary blend” or “performance complex” — a single combined weight covering several ingredients together, rather than a separate milligram amount next to each one. That matters because the evidence above is dose-dependent: caffeine's benefit shows up around 2 to 6 mg/kg, beta-alanine's tingling effect shows up around 800 mg, creatine's loading protocol uses roughly 20 g/day. When a label doesn't disclose how much of a given ingredient is actually in the blend, there's no way to check it against the amounts that research is based on — it could be dosed in the studied range, well under it, or, for an ingredient like caffeine with a documented upper safety threshold, stacked higher than expected once you count every other caffeine source in your day. ODS also notes, more broadly, that most ingredient combinations in these products haven't been separately studied, so even a fully disclosed label doesn't tell you how the ingredients behave together.
Checking a Label Before You Buy
- Look at the Supplement Facts panel for a milligram amount listed next to each ingredient, not just a combined blend total.
- Compare any disclosed amounts against the ranges above to see whether a product is dosed anywhere near what was actually studied.
- Add up caffeine from every source in your day — coffee, tea, energy drinks, other supplements — against the pre-workout dose, not just the pre-workout alone.
- Check whether the product carries third-party sport-certification (NSF Certified for Sport, Informed-Choice, or the Banned Substances Control Group), which screens for undisclosed stimulants or banned substances.
- Keep in mind that the FDA does not test or pre-approve dietary supplements before they're sold; manufacturers are responsible for safety and truthful labeling, and FDA/FTC act only after a problem is identified. FDA has specifically prohibited certain ingredients once sold in this category — including DMAA, ephedra, and androstenedione — because they were found unsafe.
Worksheet: Track Your Pre-Workout and Your Routine Before You Decide
Before adding a pre-workout product — or deciding to drop one — it helps to have this written down rather than relying on memory:
- Source and amount: What ingredient(s), and how much of each (if disclosed)? Is any part of it a proprietary blend with no individual amount listed?
- Timing: How long before training are you taking it, and does that match the window used in research for that ingredient (for example, caffeine's 15–60 minutes, or beet juice's 2.5–3 hours)?
- Sleep and symptom effects: Any changes in sleep, heart rate, anxiety, GI discomfort, or tingling since starting it?
- Current medicines and supplements: Are you taking anything that could interact — for example, caffeine's clearance from the body can be slowed by cimetidine (an ulcer medication), which raises the risk of caffeine side effects.
- Hydration and food context: Are you taking it on an empty stomach, dehydrated, or alongside other stimulant-containing products?
- A safer next question: Based on what you've written down, what's the one thing worth asking a health care provider or pharmacist about before your next purchase or dose change?
Fitting Pre-Workout Into a Broader Routine
None of these ingredients substitute for the training itself. CDC guidance for adults calls for at least 150 minutes a week of moderate-intensity aerobic activity (or 75 minutes of vigorous activity, or an equivalent mix), plus muscle-strengthening activity on two or more days a week. For readers building that kind of structure through a bodyweight or app-guided program — our look at BetterMe Calisthenics covers how a structured, equipment-free routine like that is put together — a pre-workout ingredient question usually comes down to whether it's addressing a real gap, such as consistent afternoon fatigue before an endurance session, rather than a belief that it will substitute for consistency and progression.
When to Loop In a Health Care Provider
ODS advises talking to a health care provider before starting a performance supplement, and says this is particularly important for teenagers or anyone with an existing medical condition or taking regular medication. Teenagers are advised to cap caffeine intake well below the adult range — no more than 100 mg a day — and pediatric guidance cited in the ODS fact sheet holds that any edge a teen athlete might get comes from eating well and training properly, not from the supplement itself. If you take prescription or over-the-counter medication regularly, mention any performance supplement you're considering to your provider or pharmacist rather than checking for interactions on your own.
The goal of a worksheet like the one above isn't to arrive at a verdict on any specific product — it's to get your actual exposure (ingredients, amounts where disclosed, timing, and anything else you're already taking) written down clearly enough that you, or a health care provider, can tell whether a product is addressing something real or just adding an unknown quantity to your routine.