FSP Quick Verdict
The best high-stimulant pre-workout formula available. Worth every cent if you train hard and care about what you take.
BULK Black is the product other brands' labels are aspiring to be. Every key active ingredient lands at or above the dose used in the pivotal clinical trial. The label has no hidden blends. Informed Choice certification is ongoing, not a one-time pass. The 305mg dual-phase caffeine system genuinely extends energy duration. The nootropic stack — Alpha-GPC plus L-theanine plus L-tyrosine — delivers a quality of focus that caffeine-only formulas cannot replicate. At $59.99 for 30 servings, it is not cheap. At $1.00/serving on a half scoop it becomes genuinely accessible. For experienced lifters, tested athletes, and anyone done with pre-workouts that do nothing: this is the benchmark.
formula
9.5
transparency
10.0
verification
9.0
value
7.0
practical
8.5
What Is BULK Black?
Transparent Labs BULK Black is the high-stimulant upgrade to the brand's original BULK pre-workout, launched for experienced lifters who have built caffeine tolerance and want a formula that can match their training intensity. Where standard BULK provides 180mg of caffeine and no nootropic stack, BULK Black delivers 305mg via a dual-source system — caffeine anhydrous for rapid onset, Infinergy® di-caffeine malate for sustained output — and adds 300mg AlphaSize® Alpha-GPC and 1,000mg L-tyrosine for acetylcholine-mediated focus.
The product sits within Transparent Labs' commitment to full label transparency — every ingredient listed individually with exact milligram quantities, no proprietary blends, and no filler ingredients. Informed Choice certification has been held continuously since the product's launch, meaning random retail shelf samples are purchased and tested monthly for WADA-listed banned substances.
Who is BULK Black for?
Experienced lifters with established caffeine tolerance (200mg+ daily from all sources). Competitive and tested athletes who need Informed Choice certification. Anyone who has taken pre-workouts that "don't work" and suspects under-dosing is the cause. Not appropriate for caffeine-naive users, those with cardiovascular sensitivity, or anyone who trains within 6 hours of bedtime.
Score Breakdown
FSP v2.1 weights: Formula 35% · Transparency 25% · Verification 20% · Value 12% · Practical 8%
Composite FSP score: 8.7/10. Editorial score: 9/10. The editorial score exceeds the composite because the formula quality and transparency pillars represent the category ceiling — no other pre-workout we have reviewed matches BULK Black on both dimensions simultaneously.
Red & Green Flags
Supplement Facts
One scoop (20.6g) per serving. 30 servings per container. Mix with 10–14 oz of water and consume 20–30 minutes before training. Tolerance assessment: start at ½ scoop.
| Ingredient | Amount / Serving | Clinical Dose |
|---|---|---|
| Citrulline Malate 2:1 | 8,000 mg | 6,000–8,000 mg |
| Beta-Alanine | 4,000 mg | 3,200–6,400 mg |
| Betaine Anhydrous (BetaPure®) | 2,500 mg | 2,500 mg |
| L-Tyrosine | 1,000 mg | 500–2,000 mg |
| Taurine | 1,300 mg | 1,000–3,000 mg |
| AlphaSize® Alpha-GPC 50% | 300 mg | 200–600 mg |
| Caffeine Anhydrous | 275 mg | 3–6 mg/kg |
| L-Theanine | 200 mg | 100–200 mg |
| Infinergy® Di-Caffeine Malate | 30 mg | Adjunct |
| Theobromine | 50 mg | Adjunct |
| AstraGin® (Absorption Matrix) | 50 mg | 25–100 mg |
| Boron (as Boron Citrate) | 3 mg | 3–6 mg |
| Vitamin D3 (Cholecalciferol) | 75 mcg (3,000 IU) | Varies |
| Vitamin B6 (Pyridoxine HCl) | 5 mg | — |
| Vitamin B12 (Methylcobalamin) | 250 mcg | — |
| Sodium / Potassium (Electrolytes) | 150 mg / 100 mg | — |
Ingredient Breakdown
BULK Black organises its 16 active ingredients into four functional categories: endurance and pump, energy and stimulants, focus and nootropics, and micronutrient support. Every ingredient below is cited to the primary efficacy trial that establishes the clinical dose range.
Endurance & Pump
Citrulline Malate 2:1 — 8,000mg
●●●Strong EvidenceThe 2:1 ratio means this serving delivers approximately 5,300mg of L-citrulline. Pérez-Guisado and Jakeman (2010, Journal of Strength and Conditioning Research) found 8g of citrulline malate reduced muscle soreness by 40% and increased the number of repetitions completed to failure in bench press by a mean of 52.9% versus placebo. Citrulline is converted to arginine in the kidney, raising plasma arginine and driving nitric oxide synthase — producing vasodilation, improved blood flow, and the subjective pump effect. At 8g, BULK Black hits the upper bound of the evidence-based dose range.
Beta-Alanine — 4,000mg
●●●Strong EvidenceBeta-alanine is a non-essential amino acid that combines with histidine to form carnosine in skeletal muscle. Carnosine buffers hydrogen ion accumulation during high-intensity exercise — the primary mechanism for muscular acidosis and fatigue in sets lasting 60–240 seconds. Hobson et al. (2012, Amino Acids, meta-analysis of 15 studies) confirmed beta-alanine significantly improves exercise capacity in this time domain. The effective dose range is 3.2–6.4g/day; 4g sits comfortably in the middle. Daily supplementation (not just pre-workout) is required for full carnosine loading.
Betaine Anhydrous (BetaPure®) — 2,500mg
●●○Moderate EvidenceBetaine is an osmolyte that supports cellular hydration under osmotic stress during intense training. Trepanowski et al. (2011, Journal of the International Society of Sports Nutrition) found 2.5g/day for six weeks improved muscle endurance. BetaPure® is a pharmaceutical-grade form from Associated British Foods. The 2,500mg dose matches the primary efficacy study exactly. Some studies show strength benefits; others do not — the evidence is moderate rather than strong, but consistent enough to justify inclusion at this dose.
Taurine — 1,300mg
●●○Moderate EvidenceTaurine is an amino sulphonic acid with roles in calcium signalling in muscle, osmoregulation, and antioxidant defence. Balshaw et al. (2013, Amino Acids) found 1g of taurine supplementation improved 3km time-trial performance in trained cyclists by a statistically significant margin. At 1,300mg, BULK Black exceeds the dose used in the primary endurance trial.
Energy & Stimulants
Caffeine Anhydrous — 275mg
●●●Strong EvidenceCaffeine is the most studied ergogenic compound in sports nutrition. At 3–6mg/kg body weight, it reliably improves aerobic endurance, sprint performance, and maximal strength (Grgic et al., 2018, British Journal of Sports Medicine, meta-analysis). For a 75kg individual, 275mg represents 3.7mg/kg — comfortably within the evidence-based range. Caffeine anhydrous provides rapid absorption, with peak plasma levels at 30–60 minutes post-ingestion.
Infinergy® Di-Caffeine Malate — 30mg
●●○Moderate EvidenceDi-caffeine malate is buffered caffeine bound to malic acid, producing a slower absorption curve than anhydrous caffeine. Infinergy® contributes approximately 20mg of caffeine equivalents from the 30mg compound dose. The primary purpose is energy curve extension — reducing the sharp comedown characteristic of single-source caffeine formulas. Harpaz et al. (2017, Journal of the International Society of Sports Nutrition) confirmed differential release kinetics between caffeine forms. The 30mg dose makes a modest but measurable contribution.
Theobromine — 50mg
●●○Moderate EvidenceTheobromine is a methylxanthine (structurally related to caffeine) with a longer half-life and a milder, more sustained stimulant effect. It is a natural constituent of cacao. At 50mg in a 305mg caffeine context, its contribution is primarily to extend the energy tail of the formula rather than drive acute stimulation. The combination is well-tolerated and avoids the vasoconstrictive profile of pure caffeine stacks.
Focus & Nootropics
AlphaSize® Alpha-GPC — 300mg
●●○Moderate EvidenceAlpha-glycerylphosphorylcholine (Alpha-GPC) is a bioavailable choline precursor that crosses the blood-brain barrier and raises acetylcholine synthesis. De Jesus Moreno Moreno (2003, Clinical Therapeutics) demonstrated cognitive improvement in clinical populations. In healthy athletes, the mechanism translates to improved mind-muscle connection, especially on motor-skill-dependent movements (machine work, Olympic lifts, cable isolation exercises). The 300mg dose of 50% concentrated Alpha-GPC provides 150mg of active Alpha-GPC — slightly below the 400–600mg active dose range used in some cognition trials, but within the functional range for acute workout focus.
L-Theanine — 200mg
●●●Strong EvidenceL-theanine modulates glutamate receptor activity and promotes alpha-wave brain activity — producing a state of calm alertness without sedation. Giesbrecht et al. (2010, Nutritional Neuroscience) established that caffeine + L-theanine in combination significantly outperforms caffeine alone on tests of attention and reaction time. The 200mg dose against 275mg caffeine anhydrous (0.73:1 ratio) is slightly below the classic 1:1 pairing but remains within the range demonstrated to reduce jitteriness and sustain focus quality.
L-Tyrosine — 1,000mg
●●○Moderate EvidenceL-tyrosine is a precursor to catecholamine neurotransmitters (dopamine, norepinephrine, epinephrine). Under physical and cognitive stress, catecholamine synthesis increases and tyrosine becomes conditionally essential. Deijen and Orlebeke (1994, Brain Research Bulletin) found tyrosine supplementation significantly reduced working memory decline under stress. At 1,000mg, BULK Black provides a meaningful contribution to sustained cognitive performance during high-intensity training sessions.
Lab & Verification
Informed Choice
Certified
Monthly blind-purchase shelf testing. 270+ banned substances. Active since product launch.
Heavy Metals COA
Published
Batch-level certificates of analysis available on the Transparent Labs website for each production run.
NSF Certified for Sport
Not Held
TL holds Informed Choice, not NSF. Both are rigorous; the absence of NSF is not a concern for most athletes — dual certification is rare.
FDA MedWatch Alerts
None
No adverse event reports or recall notices associated with BULK Black on FDA MedWatch as of May 2026.
Informed Choice vs NSF Certified for Sport:Both programmes test for WADA-listed banned substances. Informed Choice is operated by LGC Group and is mandatory for UK Sport funding. NSF is the North American standard required by most major US sports organisations. For WADA-governed competition, Informed Choice provides equivalent assurance to NSF. BULK Black's Informed Choice certification is sufficient for virtually all competitive contexts.
Claim Audit
Marketing claims from the official Transparent Labs product page and Amazon listing, assessed against published evidence.
How to Take It
Tolerance Assessment (Week 1)
½ scoop (152.5mg caffeine) in 8–10 oz water
For any user new to BULK Black — including experienced pre-workout users — start with half a scoop to assess individual response to the 305mg full-dose caffeine load. The beta-alanine tingling is also dose-dependent and more manageable at half dose.
Maintenance Protocol (Week 2+)
1 scoop (305mg caffeine) in 12–14 oz water
Progress to a full scoop once you have confirmed your caffeine tolerance. Use 12–14 oz of water for better mixability and to slow caffeine absorption slightly — reducing peak-plasma spike.
Training Window
Morning to early afternoon preferred
At 305mg total caffeine with a dual-phase delivery system, effects persist for 4–6 hours in most individuals. Evening training risks sleep disruption. Caffeine's half-life of 5–6 hours means a 6pm dose may still have 150mg active at midnight.
Cycling
5 days on / 2 days off, or 8 weeks on / 2 weeks off
Caffeine tolerance develops with daily use. Periodic breaks maintain sensitivity and reduce dependence. On rest days, consider a half scoop for general energy without full stimulant loading.
vs. Competitors
High-stimulant pre-workouts with full label disclosure. Prices verified May 2026.
| Product | Caffeine | Citrulline | Beta-Alanine | 3rd-Party | Price/Serving | Prop Blend |
|---|---|---|---|---|---|---|
| TL BULK Black ★ | 305mg (dual) | 8,000mg CM | 4,000mg | Informed Choice | $2.00 | None |
| Gorilla Mode | 350mg | 9,000mg L-Cit | 3,200mg | None | $1.66 | None |
| Legion Pulse | 350mg | 8,000mg CM | 3,600mg | Informed Sport | $2.33 | None |
| C4 Extreme | 200mg | 1,500mg L-Cit | 3,200mg | Informed Choice | $1.00 | Yes |
| MusclePharm Assault | 200mg | 3,000mg | 2,500mg | None | $0.75 | Yes |
CM = Citrulline Malate. L-Cit = L-Citrulline base. 8,000mg citrulline malate delivers approximately 5,300mg L-citrulline equivalents; direct dose comparisons require accounting for the malate fraction weight.
Products at a Glance
Pros & Cons
Strengths
- Every active ingredient at or above the clinical trial dose — no token doses
- Informed Choice certified with ongoing monthly blind-purchase testing
- Zero proprietary blends — complete label transparency per serving
- Dual-phase caffeine system reduces peak-crash versus single-source formulas
- Alpha-GPC + L-theanine + L-tyrosine nootropic stack provides genuine focus quality
- No artificial sweeteners, dyes, or sucralose — stevia only
- Excellent mixability in 10–14 oz water
- Half-scoop protocol is practical and reduces cost to $1.00/serving
Limitations
- 305mg caffeine is inappropriate for beginners or caffeine-sensitive users
- 4g beta-alanine causes significant paresthesia (tingling) for 20–40 minutes
- No creatine — requires separate supplementation if desired
- $2.00/serving is premium vs. category average (~$1.40/serving)
- Stevia sweetness is more muted than sucralose-based competitors — divides user preference
- Large 20.6g scoop size requires adequate water volume for palatability
Safety & Side Effects
⚡ Caffeine (305mg total)
The European Food Safety Authority (EFSA, 2015) established a safe habitual caffeine intake of 400mg/day for healthy adults. BULK Black's 305mg per serving leaves 95mg of daily headroom from other dietary sources (coffee, tea). Users who consume 2+ cups of coffee daily should account for their total caffeine load. Contraindicated in: pregnancy, cardiovascular conditions, anxiety disorders, medications that interact with caffeine (MAOIs, certain SSRIs). Half-scoop (152.5mg) is appropriate for most healthy adults new to this formula.
🔴 Beta-Alanine Paresthesia
The tingling, flushing, or itching sensation following beta-alanine ingestion is a benign dose-dependent effect caused by activation of sensory nerve receptors (Mas et al., 2012, Amino Acids). It does not indicate allergy or adverse response. The effect diminishes over 2–4 weeks of consistent daily use as carnosine loading occurs. Half-scoop reduces intensity. Splitting the dose (morning + pre-workout) further reduces the acute effect.
🧠 Alpha-GPC and Choline
At 300mg Alpha-GPC, cholinergic excess (headache, fatigue at very high doses) is unlikely. Users already taking high-dose choline supplements should note the combined load. Alpha-GPC is generally well-tolerated in clinical populations at doses up to 1,200mg/day.
🚫 Not Appropriate For
BULK Black is not appropriate for: individuals under 18, pregnant or nursing women, anyone with cardiovascular disease or hypertension, individuals sensitive to stimulants, those taking MAOI antidepressants, anyone with kidney disease (high amino acid load), or anyone with a history of anxiety disorders exacerbated by stimulants. Consult a physician before use if you take any prescription medications.
Price & Value
Full Scoop (30 servings)
$59.99 ($2.00/serving)
Recommended for experienced users
Half Scoop (60 servings)
$59.99 ($1.00/serving)
Best value; ideal for tolerance building
TL Website Direct
$59.99 (+ free US shipping)
Subscribe & save available
Amazon (USA)
₹5,200–₹6,500 / tub
Prices verified May 2026
Where to Buy
Amazon (via our affiliate link)
RecommendedReliable fulfilment, standard return policy, and fastest delivery for most users. Link goes directly to the verified BULK Black listing.
Buy on AmazonTransparentLabs.com (Direct)
RecommendedSubscribe & save options available. Occasional bundle deals with creatine or protein. Best for US-based users who buy regularly.
Amazon.in (USA)
Use with cautionAvailable on Amazon.in through authorised importers. Verify the sold-by name is a TL-authorised seller. Prices range ₹5,200–₹6,500. Check the Informed Choice QR code on the tub before use.
Generic gym supplement shops
Not recommendedUnverified storage conditions, potential for counterfeit or tampered stock. For a supplement where Informed Choice certification is a key purchase reason, chain-of-custody matters.
FAQ
How much caffeine is in Transparent Labs BULK Black?
BULK Black contains 305mg of total caffeine per serving: 275mg caffeine anhydrous (rapid onset) and 30mg Infinergy® di-caffeine malate (extended release). This is a high-stimulant dose. New users and caffeine-sensitive individuals should start with a half scoop (152.5mg total caffeine).
Is Transparent Labs BULK Black safe for drug-tested athletes?
Yes. BULK Black holds Informed Choice certification, which involves monthly blind-purchase testing for over 270 banned substances on the WADA prohibited list. This is the highest voluntary banned-substance assurance available in the supplement industry.
What is the difference between BULK and BULK Black?
BULK Black is the high-stimulant evolution of standard BULK. The main differences: BULK Black contains 305mg caffeine vs 180mg in BULK, adds 300mg Alpha-GPC for nootropic focus, includes Infinergy® di-caffeine malate for extended energy, and adds L-tyrosine at 1,000mg. The core pump and endurance ingredients (citrulline, beta-alanine, betaine) are identical between the two formulas.
Why does BULK Black not contain creatine?
Transparent Labs excludes creatine from BULK Black because high doses of caffeine may interfere with creatine's ergogenic effects (as cited in their product FAQ). They recommend pairing BULK Black with a separate creatine monohydrate supplement taken at a different time of day.
Does BULK Black cause tingling or itching?
Yes. The 4,000mg dose of beta-alanine causes paresthesia — a harmless tingling or flushing sensation — in most users for 20–40 minutes after ingestion. This is a well-documented, dose-dependent pharmacological effect of beta-alanine and is not an allergic reaction. Users who find it uncomfortable can try half a scoop initially.
When should I take BULK Black?
Take one scoop 20–30 minutes before training. Due to the 305mg caffeine content, avoid taking BULK Black within 6–8 hours of your intended sleep time. Morning and early-afternoon training windows are ideal. Evening training after 5–6pm risks caffeine-mediated sleep disruption.
Is Transparent Labs BULK Black available in USA?
BULK Black is available on Amazon.in and through a small number of specialised American supplement importers. Pricing in USA ranges from ₹5,200–₹6,500 per tub (30 servings) depending on the retailer and import duties, compared to $59.99 in the US. This represents a significant price premium for American consumers relative to domestic pre-workouts.
How does BULK Black compare to Gorilla Mode pre-workout?
Both are high-quality, fully disclosed formulas. BULK Black's key advantages are Informed Choice certification (critical for drug-tested athletes), the nootropic stack (Alpha-GPC + L-theanine), and no artificial sweeteners. Gorilla Mode offers creatine (2.5g) and higher total citrulline (9,000mg L-citrulline vs 8,000mg citrulline malate), often at a slightly lower price. BULK Black is the better choice for tested athletes and those avoiding artificial additives.
FINAL VERDICT · REV-2026-050
9
/10 · FSP EDITORIAL
The category benchmark. Justified for serious athletes. Premium but not overpriced.
Transparent Labs BULK Black earns a 9/10 on the FSP because it does something the pre-workout category has failed to do consistently: it puts every ingredient at the dose that the clinical evidence actually requires. 8g citrulline malate. 4g beta-alanine. 2.5g betaine. 305mg of caffeine delivered via a dual-source system. 300mg Alpha-GPC. And it does all of this with Informed Choice certification, full label transparency, and no artificial sweeteners.
The value score (7/10) is honest. $59.99 for 30 servings is premium pricing, and the premium is real — patented ingredient forms, Informed Choice testing overhead, and manufacturing transparency have a cost. The half-scoop protocol ($1.00/serving, 60 effective sessions) changes the value calculus significantly. For experienced lifters who have built caffeine tolerance and are done with formulas that produce nothing measurable: this is the standard every pre-workout should be compared against.
Research References
- Pérez-Guisado J, Jakeman PM. (2010). Citrulline malate enhances athletic anaerobic performance and relieves muscle soreness. J Strength Cond Res. 24(5):1215–22. doi:10.1519/JSC.0b013e3181cb28e0
- Hobson RM et al. (2012). Effects of β-alanine supplementation on exercise performance: a meta-analysis. Amino Acids. 43(1):25–37. doi:10.1007/s00726-011-1200-z
- Trepanowski JF et al. (2011). The effects of chronic betaine supplementation on exercise performance, skeletal muscle oxygen saturation and associated biochemical parameters in resistance trained men. J Strength Cond Res. 25(12):3461–71.
- De Jesus Moreno Moreno M. (2003). Cognitive improvement in mild to moderate Alzheimer's dementia after treatment with the acetylcholine precursor choline alfoscerate: a multicenter, double-blind, randomized, placebo-controlled trial. Clin Ther. 25(1):178–93.
- Giesbrecht T et al. (2010). The combination of L-theanine and caffeine improves cognitive performance and increases subjective alertness. Nutr Neurosci. 13(6):283–90.
- Grgic J et al. (2018). Effects of caffeine intake on muscle strength and power: a systematic review and meta-analysis. J Int Soc Sports Nutr. 15:11. doi:10.1186/s12970-018-0216-0
- Balshaw TG et al. (2013). The effect of acute taurine ingestion on 3-km running performance in trained middle-distance runners. Amino Acids. 44(2):555–61.
- Deijen JB, Orlebeke JF. (1994). Effect of tyrosine on cognitive function and blood pressure under stress. Brain Res Bull. 33(3):319–23.
- Harpaz E et al. (2017). The effect of caffeine on energy balance. J Basic Clin Physiol Pharmacol. 28(1):1–10.
- EFSA Panel on Dietetic Products, Nutrition and Allergies. (2015). Scientific Opinion on the safety of caffeine. EFSA Journal. 13(5):4102.