A1
L-citrulline
- Product declaration
- L-Citrulline (fermented): 6.5 g
- 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
Taurine
- Product declaration
- Taurine: 2 g
- Selected studied range
- 1000 to 3000 mg
- Protocol and duration
- per day, acutely across 6 to 15 days
- Studied context
- Studied for aerobic performance (VO2max, time-to-exhaustion, time-trial performance), anaerobic/strength performance, exercise-induced muscle damage, and recovery. A 2018 review ("Taurine in sports and exercise," PMC8152067) reports small-to-moderate improvements across several of these outcomes in some studies.
- Limitations
- The 2018 review states plainly: "limited and varied findings prohibit definitive conclusions regarding the efficacy of taurine on aerobic and anaerobic performance," and separately notes no peer-reviewed evidence exists for an independent role of taurine in skeletal-muscle hypertrophy.
Selected evidence: Taurine in sports and exercise, 2018 · Open source
A2
Caffeine
- Product declaration
- Total caffeine from all declared sources: 274 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