A1
L-citrulline
- Product declaration
- L-Citrulline: 6000 mg
- Selected studied range
- 3000 to 9000 mg
- Protocol and duration
- per day, in the studies NIH ODS summarizes
- Studied context
- Studied as a nitric-oxide pathway precursor (converted to arginine via the urea cycle) for aerobic exercise performance measures such as oxygen-uptake (VO2) kinetics, blood lactate, and rate of perceived exertion, and for acute resistance-exercise performance and muscle oxygenation. NIH ODS describes evidence for enhancing performance as limited, with few studies and conflicting results.
- Limitations
- A 2022 systematic review/meta-analysis found no significant benefit for endurance-performance outcomes specifically. A single 8 g acute dose did not enhance isometric force production, muscle endurance, or muscle-oxygenation parameters in one resistance-exercise study. NIH ODS characterizes overall performance-enhancement evidence as limited.
Selected evidence: NIH ODS, Dietary Supplements for Exercise and Athletic Performance · Open source
A2
Beta-alanine
- Product declaration
- Beta Alanine: 3200 mg
- Selected studied range
- 4000 to 6000 mg
- Protocol and duration
- per day in divided doses, for at least 2 to 4 weeks, not as a single pre-workout dose
- Studied context
- Studied for high-intensity exercise capacity in the 60-240 second range via elevation of muscle carnosine, which acts as an intracellular pH buffer against acidosis. ISSN 2015 position stand: greatest performance benefits in "open end-point" tasks/time trials lasting 1-4 minutes; some benefit noted in aerobic exercise up to roughly 25 minutes; attenuation of neuromuscular fatigue, particularly noted in older adults.
- Limitations
- Strength/resistance-training outcomes remain mixed; training volume may increase without a clear strength gain. Tasks under 60 seconds do not show benefit. Endurance benefit beyond about 25 minutes is not established. Long-term safety data beyond roughly a year, and effects in special/tactical populations, are flagged as needing more research.
Selected evidence: ISSN position stand on beta-alanine, 2015 · Open source
A1
Betaine anhydrous
- Product declaration
- Betaine Anhydrous: 2500 mg
- Selected studied range
- 2000 to 5000 mg
- Protocol and duration
- per day, studied for up to 15 days
- Studied context
- NIH ODS describes betaine as studied for strength- and power-based performance in bodybuilders and cyclists, with "potential but modest" improvements from a limited set of small, sometimes conflicting studies. A 2024/2025 systematic review focused specifically on endurance performance (VO2max, time-to-exhaustion, time-to-completion, power output).
- Limitations
- The endurance systematic review explicitly states "limited and inconclusive evidence regarding the definitive ergogenic effect of betaine supplementation on endurance exercise performance". Only 2 of 5 reviewed studies showed a significant improvement, and the authors call for "additional, more rigorous research."
Selected evidence: NIH ODS, Dietary Supplements for Exercise and Athletic Performance · Open source
A2
L-tyrosine
- Product declaration
- L-Tyrosine: 2000 mg
- Selected studied range
- 2000 to 2000 mg
- Protocol and duration
- per day for five days, in the cadet study
- Studied context
- Studied as the dietary precursor to norepinephrine for mitigating cognitive performance decrements under acute stress. A 2015 Military Medicine evidence review (rapid evidence assessment, 14 trials: 10 RCTs + 4 controlled clinical trials) issued a "weak recommendation" in favor of tyrosine for cognitive stress specifically, stating "all studies showed a positive effect" on that outcome. A widely cited primary study (Deijen et al. 1999, Brain Research Bulletin) gave cadets 2 g tyrosine daily for five days during a combat training course and found better memory and tracking-task performance, plus lower systolic blood pressure, versus a carbohydrate control.
- Limitations
- The 2015 Military Medicine review states explicitly that "no recommendation could be made" for tyrosine's effect on physical performance under stressful physical conditions, and concludes "available evidence is insufficient to make confident recommendations on the effectiveness of tyrosine for mitigating stress effects on physical/cognitive performance" overall, despite the positive signal on cognition. A separate heat-stress study found tyrosine ingestion did not influence cognitive function or physical performance during exercise heat stress despite raised serum tyrosine. NIH ODS's exercise/athletic-performance fact sheet does not cover tyrosine at all.
Selected evidence: Deijen et al., Brain Research Bulletin, 1999
A2
Agmatine sulfate
- Product declaration
- Agmatine Sulfate: 1000 mg
- Selected studied range
- No dose range selected
- Protocol and duration
- Not recorded in the selected comparison
- Studied context
- Human data is comparatively sparse. A randomized double-blind placebo-controlled trial studied oral agmatine sulfate (1,335-3,560 mg/day for up to 3 weeks) for lumbar disc-associated radiculopathy (a clinical/pain context, not sports performance). A 2019 Scientific Reports paper examined safety and neurochemical profiles of acute and sub-chronic oral agmatine sulfate treatment.
- Limitations
- Sports-performance-specific human efficacy data for agmatine sulfate (e.g., a dedicated ISSN position stand) was not located in this research pass. Evidence located centers on safety/tolerability and non-sports clinical contexts rather than an authoritative performance-outcome verdict. Long-term safety in larger populations remains an open gap per the safety literature reviewed.
Selected evidence: Safety and neurochemical profiles of oral agmatine sulfate, 2019 · Open source
A1
Choline bitartrate
- Product declaration
- Vitacholine Choline L (+) Bitartrate: 500 mg
- Selected studied range
- 425 to 550 mg
- Protocol and duration
- Adequate Intake for adults, a nutrient reference and not an ergogenic dose
- Studied context
- NIH ODS's Choline Health Professional fact sheet establishes choline's core physiological roles: synthesis of phosphatidylcholine and sphingomyelin for cell-membrane structure, acetylcholine (a neurotransmitter for memory, mood, and muscle control) production, methyl-group donation, gene-expression modulation, and brain development. Choline bitartrate is named as one of three supplement forms (with phosphatidylcholine and lecithin).
- Limitations
- NIH ODS states explicitly: "No studies have compared the relative bioavailability of choline from these different forms". Meaning choline bitartrate's absorption/efficacy relative to phosphatidylcholine, lecithin, or non-bitartrate forms (like alpha-GPC) is not established by NIH's own review.
Selected evidence: NIH ODS, Choline fact sheet · Open source
A2
Vincamine
- Product declaration
- Vincamine: 10 mg
- Selected studied range
- No dose range selected
- Protocol and duration
- Not recorded in the selected comparison
- Studied context
- Vincamine has been studied as a pharmacologically active alkaloid in older human clinical and pharmacokinetic research. Those studies are not pre-workout efficacy studies and do not establish a dietary-supplement dose range.
- Limitations
- The product label does not establish pharmaceutical formulation, purity, or equivalence to the preparations in the older studies. No sports-performance benefit is established by the cited sources.
Selected evidence: Severe ventricular arrhythmia following parenteral administration of vincamine · Open source
A2
Caffeine
- Product declaration
- Total caffeine from all declared sources: 376 mg
- Selected studied range
- 140 to 420 mg
- Protocol and duration
- 2 to 6 mg per kg body mass, 15 to 60 minutes before exercise, shown here for a 70 kg adult
- Studied context
- Studied for endurance-type aerobic exercise (moderate to large ergogenic effect, most consistent evidence category per ISSN 2021), muscular endurance and movement velocity in resistance exercise (small to moderate effects), sprinting/jumping/throwing (2-7% improvements), and cognitive attention/vigilance under fatigue. NIH ODS notes it "might enhance performance in endurance-type activities... And intermittent, long-duration activities."
- Limitations
- Minimal effective dose remains unclear. Repeated-sprint performance benefit is inconsistent and the ISSN position stand says this "requires further research." Effects of habitual/chronic caffeine use on the ergogenic response are described as equivocal.
Selected evidence: ISSN position stand on caffeine and exercise performance, 2021, with NIH ODS · Open source