A2
Citrulline malate
- Product declaration
- Citrulline Malate: 6 g
- Selected studied range
- 6000 to 8000 mg
- Protocol and duration
- single acute dose, 40 to 60 minutes before training
- Studied context
- Studied for resistance-exercise repetition performance/muscular endurance, cycling performance, muscle-damage recovery, and muscle soreness. A 2021 critical review notes a single acute 8 g dose "may, albeit not consistently, increase muscular endurance-strength performance," with a meta-analysis finding an average 6.4% increase in repetitions with 6-8 g dosed 40-60 minutes pre-exercise, with a stronger trend for lower-body than upper-body exercises.
- Limitations
- The same review states there is "little evidence to advocate its use in the production and maintenance of muscular power, maximal strength, recovery of muscular function, or supporting muscular adaptations," calls cycling-performance effects "scarce," and says claims about reduced muscle soreness lack consistent support. Overall efficacy is called "ambiguous." The review also flags a real-world quality-control problem: commercial products often do not match the citrulline:malate ratio used in the research they cite.
Selected evidence: A critical review of citrulline malate supplementation and exercise performance, 2021 · Open source
A2
Beta-alanine
- Product declaration
- Beta-Alanine: 2 g
- 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: 1.5 g
- 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
Alpha-GPC
- Product declaration
- alpha-GPC: 150 mg
- Selected studied range
- 300 to 600 mg
- Protocol and duration
- single dose, 30 to 90 minutes before testing or training
- Studied context
- Studied for acute cognitive performance (e.g., Stroop-test measures) and for acute power output/strength in resistance exercise. A 2024 study found both 300 mg and 600 mg doses improved Stroop-test performance in healthy young men. Separate studies cited 600 mg dosed 90 minutes pre-exercise increasing post-exercise growth hormone and peak bench-press force, and 600 mg/day over 6 days increasing lower-body isometric strength by over 3%.
- Limitations
- NIH ODS's Choline Health Professional fact sheet does not mention alpha-GPC at all, and states no studies have compared relative bioavailability across the choline supplement forms it does cover (choline bitartrate, phosphatidylcholine, lecithin). Alpha-GPC's comparative bioavailability is outside what NIH has assessed in that document. A large 2021 observational study (JAMA Network Open, South Korean national-insurance cohort, n=12,008,977 adults 50+) found an association between alpha-GPC use and 10-year stroke risk (adjusted HR 1.46, 95% CI 1.43-1.48 for total stroke) in a dose- and duration-response pattern, but the authors explicitly flag confounding limitations: alpha-GPC users were older with more comorbidities at baseline, and the study is observational (association, not proven causation).
Selected evidence: Acute alpha-GPC supplementation and cognitive performance, 2024
A4
Huperzine A
- Product declaration
- Huperzine A: 50 mcg
- Selected studied range
- No dose range selected
- Protocol and duration
- Not recorded in the selected comparison
- Studied context
- Marketed for memory, alertness, attention, concentration, and focus, and studied preliminarily in Alzheimer's disease populations (it is used as an approved pharmaceutical for this purpose in China). The DoD's Operation Supplement Safety (OPSS) resource, reviewing the evidence base, states plainly: "No reliable scientific evidence supports the use of huperzine A to enhance cognitive performance" in healthy individuals specifically.
- Limitations
- OPSS states no reliable evidence supports cognitive-enhancement use in healthy people; the Alzheimer's Association explicitly recommends against use, especially combined with prescription drugs, citing insufficient safety data and poorly understood long-term effects.
Selected evidence: Operation Supplement Safety, huperzine A · Open source
A2
Caffeine
- Product declaration
- Total caffeine from all declared sources: 300 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
