Pre-workout supplements are one of the most popular — and most polarising — products in the fitness industry. Proponents swear by the energy, focus, and endurance they deliver. Critics say it’s mostly caffeine and marketing. The truth, as ever, is more nuanced. Some ingredients in pre-workout supplements have genuinely strong evidence behind them. Others are window dressing. Here’s how to tell the difference.
What Is a Pre-Workout Supplement?
Pre-workout supplements — often called “pre-workouts” or MIPS (multi-ingredient pre-workout supplements) — are products typically taken 30–60 minutes before exercise with the goal of improving performance, energy, focus, and endurance. They are almost always formulated as a powder mixed with water.
The critical thing to understand about pre-workouts is that they are not a single product with a standardized formula — they’re a category. Two products both labeled “pre-workout” may share almost no ingredients. A 2023 analysis found that beta-alanine, caffeine, citrulline, tyrosine, taurine, and creatine are the most common ingredients — but that roughly 44% of all pre-workout ingredients appear in “proprietary blends” that don’t disclose individual quantities.
Ingredient-by-Ingredient Breakdown: What the Evidence Shows
Caffeine is the most extensively studied and consistently effective ingredient in any pre-workout supplement. It works by blocking adenosine receptors in the brain — adenosine being the chemical that promotes drowsiness — which increases alertness, reduces perceived effort, and improves both power output and muscular endurance. University Hospitals sports dietitian Kelli Santiago describes it as “a proven enhancer of athletic performance, alertness and concentration.” A 2024 review of pre-workout supplements and cardiovascular health confirmed caffeine as the dominant active ingredient in 22 of 24 studies reviewed.
Practical note: A registered dietitian at University Hospitals noted that 1–2 cups of black coffee provides 90–180 mg of caffeine — arguably the most effective ingredient in most pre-workouts — without proprietary blend fillers. If caffeine is your primary goal, coffee is a legitimate, cost-effective alternative.
Beta-alanine is a precursor to carnosine, a compound that acts as a buffer against the acid buildup in muscles during intense exercise. By raising muscle carnosine levels, beta-alanine can delay the onset of fatigue in high-intensity efforts lasting 1–10 minutes — sprints, high-rep sets, interval training. A 2017 systematic review and meta-analysis in the British Journal of Sports Medicine confirmed its ergogenic benefit for exercise capacity in this duration range. The key nuance: it requires a loading period of several weeks to build up effective carnosine levels in muscle tissue. A single dose before a workout has minimal acute effect.
Practical note: The tingling sensation (paresthesia) it causes is harmless but can be intense and distracting. It can be minimized by splitting doses throughout the day rather than taking a full dose at once.
Citrulline is converted in the body to arginine, which is then used to produce nitric oxide — a vasodilator that relaxes blood vessels and improves blood flow to working muscles. The proposed benefit is better oxygen and nutrient delivery, reduced muscle soreness, and improved endurance. A 2020 review in the Journal of Strength and Conditioning Research found positive effects on exercise performance, though the evidence is more consistent for endurance and muscular endurance than for peak strength. Many products underdose this ingredient — look for at least 6 g of L-citrulline per serving.
Practical note: Citrulline malate is a common form in supplements (citrulline bonded to malic acid). Check label doses carefully — products often include 2–3 g, which is well below the researched effective range.
Creatine monohydrate has the strongest evidence base of any sports supplement for improving strength and power. When it appears in a pre-workout, it can contribute to creatine saturation — but only if used consistently over time. The problem: many pre-workouts include 1–2 g of creatine, well below the 3–5 g daily maintenance dose that produces meaningful muscle creatine elevation. If creatine is a goal, a dedicated creatine supplement at the correct dose is more reliable than a pre-workout formulation.
See our dedicated article on Creatine Monohydrate vs. Creatine HCL for a full breakdown of the evidence.
Many pre-workouts include tyrosine (a precursor to dopamine and norepinephrine), taurine (an amino acid with proposed antioxidant and osmoregulatory effects), and B-vitamin complexes in their formulations. The evidence for any direct performance benefit from these ingredients at the doses typically found in pre-workout products is limited. They’re unlikely to cause harm at these levels, but they’re also unlikely to be a meaningful performance driver. Their primary function in many formulas appears to be label marketing rather than pharmacological effect.
What the Research Says About Multi-Ingredient Pre-Workouts
A Single-Dose Multi-Ingredient Pre-Workout Supplement Enhances Upper Body Resistance Performance (2024)
A 2024 peer-reviewed study (PMC10846641) tested a multi-ingredient pre-workout supplement containing caffeine, beta-alanine, L-citrulline, and other common ingredients against placebo in a randomized, double-blind crossover design. Results showed statistically significant improvements in upper-body resistance exercise performance — measured by total repetitions completed — in the supplement group vs. placebo. The researchers attributed the primary effect to caffeine, with beta-alanine and citrulline as supporting contributors. Critically, the improvements were meaningful in practical terms for trained individuals looking to increase training volume.
An earlier NSCA-cited study found that a pre-workout containing caffeine, B-vitamins, amino acids, creatine, and beta-alanine before exercise delayed fatigue while improving both reaction time and muscular endurance — consistent with what the individual ingredient evidence would predict.
Red Flags to Watch Out For
| Red flag | Why it matters |
|---|---|
| Proprietary blends | If ingredient amounts aren’t disclosed, you can’t verify you’re getting effective doses — or safe ones. |
| Underdosed actives | Many products include citrulline at 2 g, beta-alanine at 1 g, and creatine at 1 g — fractions of what research supports. |
| Very high caffeine | Products over 300–400 mg per serving can cause palpitations, anxiety, and sleep disruption — especially for caffeine-sensitive users. |
| No third-party testing | The supplement industry is loosely regulated. Without NSF, Informed Sport, or Informed Choice certification, label accuracy is unverified. |
| Long ingredient lists | More ingredients doesn’t mean more effectiveness. Long lists often dilute effective doses of the few ingredients that matter. |
| Late-evening use | Caffeine has a half-life of 5–6 hours. Taking a caffeinated pre-workout after 4–5 PM will likely disrupt sleep quality, negating recovery. |
Do You Actually Need a Pre-Workout?
The most valuable ingredient in most pre-workout supplements — caffeine — is available in coffee, tea, and standalone caffeine supplements at a fraction of the cost. If your goal is alertness, reduced perceived effort, and performance enhancement, a strong cup of coffee 30–45 minutes before training achieves most of what a typical pre-workout does, without proprietary blends, underdosed ingredients, or premium pricing.
Where a dedicated pre-workout product adds genuine value:
- →You want a fully dosed citrulline and beta-alanine contribution alongside caffeine in one product, with transparent labeling
- →You train at times when coffee isn’t convenient or you prefer a non-liquid caffeine source before exercise
- →You’re doing high-intensity, high-volume training where muscular endurance support from beta-alanine is a meaningful goal
- →You find the ritual and taste of a pre-workout shake helps with training motivation and adherence — which is a legitimate, underrated factor
The Bottom Line
Pre-workout supplements can work — but only the ingredients that have real evidence behind them, at the doses those studies actually used. Caffeine is the most reliable performance enhancer in the category, with strong and consistent research support. Beta-alanine and citrulline have moderate evidence at correct doses. Everything else should be viewed skeptically.
The biggest problem with the pre-workout market isn’t that the effective ingredients don’t work — it’s that most products underdose them, bury them in proprietary blends, and pad the formula with ingredients that contribute little beyond label appeal.
If you’re going to use a pre-workout, choose one with fully disclosed ingredients, doses that match the researched ranges, and third-party certification. Or save the money and drink coffee. For many people, that’s genuinely the more cost-effective path to the same result.
- →Creatine Monohydrate vs. Creatine HCL: What the Research ShowsCreatine is the supplement most worth taking seriously for long-term strength and muscle gains.
- →Should I Take a Protein Supplement? A Beginner’s GuideThe case for protein supplementation — who needs it, when, and what to buy.
- →The Best Protein Powders: Our Research-Backed PicksOur top picks by category, with quality criteria and evidence-based selection.
- →How Much Protein Do You Actually Need Per Day?Calculate your daily protein target by weight, goal, and training type.
References
1. Beyer KS, et al. A single dose multi-ingredient pre-workout supplement enhances upper body resistance exercise performance. Front Nutr. 2024. PMC10846641
2. Marczak M, et al. Pre-Workout Supplements and Their Effects on Cardiovascular Health: An Integrative Review. PMC. 2025. PMC12028264
3. Saunders B, et al. Beta-alanine supplementation to improve exercise capacity and performance: A systematic review and meta-analysis. Br J Sports Med. 2017;51(8):658–669.
4. Gonzalez AM & Trexler ET. Effects of citrulline supplementation on exercise performance in humans. J Strength Cond Res. 2020;34(5):1480–1495.
5. NSCA. Pre-Workout Supplements — An Evidence-Based Guide. nsca.com
This article is for informational purposes only. Consult a healthcare provider before starting any supplement regimen, particularly if you have a history of cardiovascular conditions or caffeine sensitivity.
