Supplements: Pre-Workout Ingredients Decoded
Citrulline requires 6-8g to meaningfully increase blood arginine and reduce fatigue. Most pre-workouts contain 1-3g. Beta-alanine needs 3.2g/day; caffeine 3-6mg/kg bodyweight for performance effects.
| Measure | Value | Unit | Notes |
|---|---|---|---|
| Evidence Tier | 1–2 | tier | Varies by ingredient — caffeine and beta-alanine Tier 1; citrulline and betaine Tier 2; others Tier 2-3 |
| Caffeine Effective Dose | 3–6 | mg/kg bodyweight | ~200-400mg for 70kg person; most pre-workouts contain 150-300mg |
| Citrulline Minimum Effective Dose | 6 | g | Many products contain 1-3g — clinically underdosed; malate form needs 8g for 6g citrulline equivalent |
| Beta-Alanine Daily Loading Dose | 3.2 | g/day | Minimum for carnosine saturation over 4-6 weeks; timing irrelevant — chronic loading matters |
| Betaine Effective Dose | 2.5 | g/day | Osmolyte and methyl donor; modest Tier 2 evidence for strength and power |
| Theanine-Caffeine Ratio | 1:2 | theanine:caffeine | 100mg theanine per 200mg caffeine reduces anxiety without impairing focus benefit |
The pre-workout supplement category is one of the most marketed and most misunderstood in the industry. Effective ingredients exist, but the majority of commercial products combine them at sub-clinical doses — a practice called “pixie dusting” — to create impressive-looking labels at minimal ingredient cost.
The Pixie Dusting Problem
A product containing 6g of a “performance matrix” cannot contain effective doses of citrulline (6g), beta-alanine (3.2g), and creatine (5g) simultaneously — the math doesn’t work. Yet many labels imply all three are present. Transparent labeling with individual ingredient doses is the single most important feature to look for when evaluating pre-workouts.
Ingredient Reference Table
| Ingredient | Standard Effective Dose | Underdosed If < | Mechanism | Evidence Tier | Typical Label Dose |
|---|---|---|---|---|---|
| Caffeine | 3-6 mg/kg (~200-400mg) | 150mg | Adenosine receptor antagonism | Tier 1 | 150-300mg (often adequate) |
| Citrulline | 6-8g (as malate: 8g) | 3g | NO pathway → vasodilation, reduced fatigue | Tier 2 | 1-4g (often underdosed) |
| Beta-Alanine | 3.2g/day (chronic) | 1.6g | Carnosine buffer → delays acid-induced fatigue | Tier 1 | 1.6-3.2g (variable) |
| Creatine | 3-5g/day | 2g | PCr resynthesis → short-burst power | Tier 1 | 1-3g (often underdosed) |
| Betaine | 2.5g/day | 1.25g | Osmolyte + methyl donor → strength, power | Tier 2 | 0.5-1.5g (usually underdosed) |
| Tyrosine | 500-2000mg acute | 500mg | Catecholamine precursor → cognitive performance under stress | Tier 2 | 100-500mg (often underdosed) |
| Taurine | 1-2g | 500mg | Osmoregulation, antioxidant, reduces caffeine jitteriness | Tier 2 | 500-1000mg (borderline) |
| L-Theanine | 100-200mg | 50mg | GABA modulation; counters caffeine anxiety | Tier 2 | 100-200mg (often adequate) |
| L-Arginine | 3-6g | N/A | NO precursor (poor bioavailability) | Tier 3 | 500-2000mg (superseded by citrulline) |
| BCAAs | N/A | N/A | Protein synthesis (redundant with adequate diet) | Tier 3 if diet adequate | 3-5g (unnecessary) |
The Theanine-Caffeine Stack
The 1:2 theanine-to-caffeine ratio (e.g., 200mg caffeine + 100mg theanine) is one of the few well-supported cognitive stacks. Theanine reduces the anxiety and jitteriness from caffeine without blunting the focus and alertness improvement. This combination consistently outperforms caffeine alone on cognitive measures in trials.
Betaine and Tyrosine in Detail
Betaine (trimethylglycine) functions as an osmolyte — it draws water into muscle cells — and as a methyl donor supporting creatine synthesis. At 2.5g/day, studies show modest improvements in strength and endurance, though effect sizes are smaller than creatine. Tyrosine is a catecholamine precursor (dopamine, norepinephrine) most effective under conditions of cognitive stress or sleep deprivation. Standard doses of 500-2000mg before training provide cognitive benefit, particularly in mentally taxing sessions.
Related Pages
Sources
- Trexler ET et al. International society of sports nutrition position stand: Beta-Alanine. J Int Soc Sports Nutr. 2015;12:30.
- Hobson RM et al. Effects of beta-alanine supplementation on exercise performance: a meta-analysis. Amino Acids. 2012;43(1):25-37.
- Pérez-Guisado J, Jakeman PM. Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. J Strength Cond Res. 2010;24(5):1215-1222.
Frequently Asked Questions
What is pixie dusting in pre-workouts?
Pixie dusting means a product lists an effective ingredient on its label but at a dose far below what studies show works. For example, listing 1g citrulline when effective doses start at 6g. It creates a credible-sounding label while cutting costs significantly. Proprietary blends make this especially easy to hide.
Are BCAAs in pre-workouts worth anything?
Only if your diet is protein-deficient. BCAAs (branched-chain amino acids) became popular before research clarified that whole protein sources containing adequate leucine (2-3g) are superior. If you eat 1.6-2.2g protein per kg bodyweight daily, adding BCAAs to a pre-workout provides no measurable benefit.
Does L-arginine in pre-workouts work?
Arginine has poor oral bioavailability — it is heavily metabolized in the gut and liver before reaching the bloodstream. Citrulline, which converts to arginine in the kidneys, raises blood arginine levels more effectively than arginine itself. Arginine as a pre-workout ingredient is a legacy compound largely superseded by citrulline.
What is a proprietary blend and why is it a red flag?
A proprietary blend groups multiple ingredients under a single combined weight, hiding individual doses. A product can legally list 'Citrulline, Beta-Alanine, Creatine (4,500mg blend)' without revealing how much of each is present. This almost always indicates underdosed individual components. Opt for transparently dosed products whenever possible.
How much caffeine is too much in a pre-workout?
Most adults tolerate 200-400mg caffeine safely. Some pre-workouts contain 300-400mg, approaching the upper end for average users. At 6mg/kg bodyweight (420mg for a 70kg person), side effects including anxiety, palpitations, and impaired fine motor control become likely. Start with half a serving to assess tolerance.