C4 Original Pre-Workout.

The gap this formula speaks to.

Public health figures the engine matched to this formula's ingredients. Reported by their source, cited and dated, never written by the brand.

Population figures from public health data. Context for the category, not a statement about any individual and not a claim about this product.

Every one of these is a fact the engine could ground.

Each line below was derived from this formula's own record at the time of verification. Nothing here was written by the brand, and nothing can be added that the evidence does not carry.

• Studied in people16 human studies on L-Citrulline back this formula, each one cited.
• A mechanism that is settledHow Vitamin B6 and Folate work is settled pharmacology.
• Studied together, not just separatelyVitamin B6 and Folate have been studied together, not only separately.
• Recent work on the recordThe most recent study on this record was published in 2025.
• Why this formatIt is a powder, so the serving scales to the amount you want and mixes into something you already drink.
• The exact form, describedThe label names its forms exactly: Pyridoxine HCl, Folinic acid, Methylcobalamin. The record says what each one is and what it suits.
• A declared blend totalMuscular Endurance & Performance Blend declares its total, 4.5 g per serving, with 5 ingredients listed by weight.
• Where it comes from and how it is madeVitamin B6 is made by synthetic.
• Positions this formula already qualifies forThis formula already qualifies for positions beyond the one it is sold into, on the evidence it carries.
• A position nobody is holding yetSome of those positions are ones almost nobody is selling to yet.

The combinations the trials actually measured.

One pairing in this formula has been studied as a combination in human trials. Each finding below is what a named study measured, cited and dated, never written by the brand.

• Folate + Vitamin B12 + Vitamin B6Heart

  In a 2025 network meta-analysis of 16 randomized trials in healthy adults, folic acid taken together with vitamins B6 and B12 lowered blood homocysteine more than any single supplement, with the 1 mg folic acid plus 7.2 mg B6 plus 20 micrograms B12 arm ranked most effective versus placebo (mean difference -1.03 micromol/L, 95% CI -1.71 to -0.36).

  Liu et al., 2025 (Nutrition Reviews)PMID 39960689

  Promising

Findings from trials that studied these actives as a combination. Context for how the actives were tested together, not a statement about any individual and not a claim about this product.

What the trials show about timing.

Time-to-effect windows the engine read from the trial record. Each is a window a named study measured, cited and dated, never written by the brand.

• Vitamin B6about 20 to 40 days to clear after stoppingBuilds with daily use

  An expert consensus on vitamin B6 use, developed by a six-member Delphi panel with a structured evidence-quality assessment, calculated from pharmacokinetic parameters that complete clearance of vitamin B6 from the body takes a washout period of about 20 to 40 days after intake stops.

  Schellack et al., 2025 (Drug Healthc Patient Saf)PMID 40395441

  Early
• Folatea median of about 36 weeks of daily intakeBuilds with daily use

  A systematic review and Bayesian meta-analysis drew on 108 articles from 14,002 screened records and modelled blood folate against folic acid intake using one-compartment pharmacokinetic models. Red blood cell folate rose 1.78 fold from baseline to steady state at 375 to 570 ug folic acid per day, and reaching that steady state took a median of 36 weeks, 95% credible interval 27 to 52 weeks. Serum or plasma folate rose 11.6% for every 100 ug per day of folic acid intake, 95% credible interval 8.4 to 14.9.

  Crider et al., 2019 (Nutrients)PMID 30609688

  Strong
• Folateabout 18 days for serum folate to reach its maximumBuilds with daily use

  A kinetic study in six healthy men aged 22 to 31 gave 3.6 umol per day, 1.6 mg, of deuterium-labelled folic acid for four weeks, with folate tracked in serum, erythrocytes and urine by microbiological assay and gas chromatography mass spectrometry. Serum folate reached its maximum concentration in about 18 days, while isotopic labelling of erythrocyte folate kept rising across the whole four weeks. After supplementation stopped, red blood cell folate and urinary folate excretion declined linearly, and serum folate fell with a slow-phase half-life of 18.7 days. One study, six men, no control group.

  von der Porten et al., 1992 (J Nutr)PMID 1588447

  Early
• L-Citrullinewithin about 1 hour of a single doseMeasured within a day

  In a randomised double-blind crossover trial in 19 recreationally active women, a single 8 g dose of citrulline malate taken 60 minutes before testing raised total work in a 5-repetition isokinetic leg extension protocol compared with placebo, with no difference in peak torque and no difference in the 50-repetition protocol. A separate crossover trial in 10 well-trained men using 12 g 60 minutes before high-intensity cycling found no change in time to exhaustion or power.

  Gills et al., 2023 (J Strength Cond Res)PMID 34319940

  Cunniffe et al., 2016 (J Strength Cond Res)PMID 26808848

  Early
• Caffeine Anhydrouswithin about 45 to 60 minutes of a single doseMeasured within a day

  In a double-blind placebo-controlled crossover trial, 15 resistance-trained women took 4 mg per kg body mass of caffeine 60 minutes before a strength and power battery. Squat one-repetition maximum rose 4.5 percent and countermovement jump height 7.6 percent against placebo. A separate crossover trial in 11 active adults began its cycling tests 45 minutes after a 3 mg per kg capsule and recorded a peak-power increase of about 4 percent on the first day of ingestion.

  Norum et al., 2020PMID 32681596

  Lara et al., 2019PMID 30673725

  Promising
• Caffeine Anhydrousheld for about 15 to 18 days of daily use, then narrowedBuilds with daily use

  One crossover trial mapped the day-to-day time course in 11 healthy active adults taking 3 mg per kg per day for 20 consecutive days. Peak cycling power in the incremental test stayed about 4.0 percent above placebo for the first 15 days and the difference then lessened. Wingate peak power was still raised on days 1, 4, 15 and 18 by about 4.9 percent. The authors describe the shrinking margin as progressive tolerance. This is one trial with 11 participants.

  Lara et al., 2019PMID 30673725

  Early

Windows measured in the cited trials. Context for how the active behaves over time, not a statement about any individual and not a claim about this product.

How each ingredient usually behaves over time.

11 ingredients, from each one's own page.

• Vitamin B6

  Nothing quick. Conversion to the active coenzyme happens within hours, but plasma pyridoxal 5-phosphate takes a couple of weeks to settle at a new level.

  Its own page, the plain answer on timing ↗

• FolateAbout four to eight weeks

  Red cell folate climbs over roughly four to eight weeks. It's a blood panel change rather than a sensation.

  Its own page, the plain answer on timing ↗

• Vitamin B12Within days

  Serum B12 rises within days of daily use. Methylmalonic acid, the marker of supply inside cells, settles across four to twelve weeks, and anything noticeable follows that.

  Its own page, the plain answer on timing ↗

• Choline

  Not an acute one. The choline pool refills over weeks of daily use, and status shows on a plasma choline reading before it shows up anywhere else.

  Its own page, the plain answer on timing ↗

• Beta-AlanineAbout 15 to 30 minutes

  Tingling can arrive 15 to 30 minutes after a large serving. The muscle carnosine rise you are actually after builds across two to four weeks of daily dosing.

  Its own page, the plain answer on timing ↗

• L-Citrulline

  Plasma arginine peaks around an hour after a dose, which is when the fuller feeling in working muscle turns up. Performance changes build across one to two weeks.

  Its own page, the plain answer on timing ↗

How each ingredient usually behaves over time, from its own page on IngredientMD. General timing for the ingredient, not a measurement of this product.

The same ingredient, carried differently.

What each form is, and where it fits in a formula. Measured findings carry the study that reported them.

• Pyridoxal

  The aldehyde form, one kinase step from the active coenzyme and not requiring the oxidase step.

  Fits

  Occurs in foods and is the circulating transport form after hepatic processing.

  Trade-off

  Rarely offered as a standalone supplement ingredient, so it is mostly relevant to understanding physiology rather than to choosing a product.

• (6S)-5-methyltetrahydrofolate, glucosamine salt

  The reduced, methylated folate anion paired with a glucosamine counter-ion, which gives a freely water-soluble crystalline solid.

  Fits

  Liquids, sachets and any format where solubility of the folate itself is the constraint.

  Trade-off

  The counter-ion is an aminosugar, which is a consideration for anyone tracking glucosamine or shellfish-sourced ingredients, and glucosamine sources vary.

• Methylcobalamin

  Cobalamin carrying a methyl group on the cobalt centre, the same species used directly by methionine synthase.

  Fits

  Oral tablets, capsules and powders where a preformed methylated cofactor is wanted.

  Trade-off

• Choline bitartrate

  Choline paired with L-(+)-tartaric acid as a crystalline, freely water-soluble salt.

  Fits

  Capsules, tablets and powders where a plain choline load is wanted and the tartrate acidity is acceptable.

  Trade-off

  A large share of the tablet weight is the tartrate counter-ion, so the label dose of salt is well above the choline it delivers.

• L-Citrulline

  The non-protein amino acid citrulline in its uncombined free form, not bonded to another acid, mineral, or carrier. Every labelled gram is citrulline itself.

  Fits

  Suits a formula that wants citrulline on its own with no added acid weight, so the panel gram and the citrulline gram are the same number. Folds cleanly into capsules and unflavored or lightly flavored powders.

  Trade-off

  It carries no malic acid, so a brand following a citrulline-malate dosing protocol cannot match gram-for-gram and has to convert. The plain powder can taste faintly bitter in a simple drink mix.

  In a randomized double-blind placebo-controlled crossover trial, 10 healthy men took 6 g/day of free-form L-citrulline for 7 days. Tolerance to severe-intensity cycling and total work completed were higher than placebo, while L-arginine at the same dose was not.

  Bailey et al., 2015 (J Appl Physiol)
• L-arginine (free-form)

  The pure free-form amino acid, carrying no counter-ion and no added acid.

  Fits

  A single labelled amino acid that holds a high proportion of arginine by weight, which suits simple single-ingredient powders and capsules with no extra acid load.

  Trade-off

  It is hygroscopic and mildly alkaline with a bitter note, and gram-level servings are bulky to deliver.

3 more

Creatine nitrate

A 1:1 salt of creatine with nitric acid. In water it dissociates into creatine and nitrate ions, which then behave independently.

Fits

Formulas that want a creatine source and a nitrate source from a single ingredient, typically in pre-workout powders where aqueous solubility at low volume matters.

Trade-off

Part of the mass is the nitrate counter-ion, so the creatine delivered per gram is lower than for a non-salted creatine source, and the nitrate load has to be counted alongside any other nitrate ingredient in the formula.

Ethyl ester (EE)

During concentration, EPA and DHA are cleaved from glycerol and each bound individually to ethanol, so every fatty acid rides on its own ethyl group rather than a shared glycerol backbone. This arrangement allows a high EPA and DHA percentage.

Fits

Suits high-concentration products where a large EPA and DHA figure per capsule is the goal and the manufacturer stops at the ester stage rather than re-esterifying.

Trade-off

Each fatty acid is bound to ethanol rather than a shared glycerol backbone, a more processed arrangement than either triglyceride form, and one that does not blend into a food-oil matrix as readily.

In a six-month double-blind RCT in 150 adults, the rise in the omega-3 index (EPA and DHA in red blood cell membranes) with the ethyl ester form was smaller than with an equal dose of re-esterified triglyceride. A two-week trial found lower serum appearance versus natural fish oil.

Neubronner et al., 2011 (Eur J Clin Nutr)PMID 21063431

Caffeine anhydrous

Dry crystalline free base with no water of crystallisation, close to a hundred percent caffeine by weight

Fits

Capsules, tablets and pre-workout powders where an exact milligram figure is needed

Trade-off

Potency by volume makes it unforgiving to measure by spoon and it dissolves slowly in cold water. The same potency is what makes accurate dosing possible on a scale

Descriptions of the form itself, read from the cited studies. Not a comparison between products and not a statement about any individual.

Powder

It is a powder, so the serving scales to the amount you want and mixes into something you already drink.

Because the effect builds and holds only with continued daily use, a steady recurring supply is the practical way to keep it going.