Endopump

A specialized sports preparation intended only for adults (21+) for self-assessment of risk. It is sterile amino acid solution for intramuscular injection — is not a medicinal product or dietary supplement in the Polish and EU legal sense. The amino acids themselves (L-arginine, L-ornithine, L-citrulline, L-lysine, glycine) are permitted by EFSA as ingredients of an oral dietary supplement, however the injection form places this preparation outside the framework of the supplement. Before making any decision, please read the “Legal Status” section and contraindications at the end of the description.

Muscle pump is a measurable hemodynamic phenomenon, not just an impression in the mirror. Vasodilation in the working muscle, increase in blood flow and inflow of plasma into the intercellular space create this characteristic “expansion” effect that advanced athletes know from recent series. The entire mechanism is connected by one signal molecule: nitric oxide (NO), produced from the amino acid L-arginine by the enzyme nitric oxide synthase.

Hence the entire category of “NO-boosters” – and hence the eternal problem of oral arginine, the bioavailability of which can be disappointingly low. EndoPump solves this problem with a different route of administration. Instead of fighting the first-pass effect of the liver and intestinal argininase, it delivers five amino acids directly to the muscle in the form of an intramuscular injection – with a bioavailability close to 100%.

The composition is not accidental: it is two overlapping axes of action in one vial. On the one hand nitric oxide axis (arginine plus citrulline) driving the pump and flow. On the other hand classic amino-stack stimulating the secretion of growth hormone (arginine plus ornithine plus lysine), described in sports literature since the 1980s. Coach Marek would say it bluntly: this is a tool for someone who already understands what an intramuscular injection is, is able to perform it sterilely and reads the label before reaching for the syringe.

It is not a “powder-to-shake pump” – it is a preparation for advanced users, with its own risk profile (pressure drop, pain at the injection site) and with a specific WADA regulatory frame that you need to know. This preparation is sterile solution of 225 mg of amino acids per milliliter in a multi-dose vial, pharmaceutical quality, purity of each amino acid verified by HPLC, identity confirmed, COA available for each batch. The liquid form in a multi-dose vial allows you to precisely measure the working volume using a graduated syringe.

EndoPump it a combination of five free amino acids in one sterile solution for intramuscular injection. Each of them has a separate function, and the whole was designed around two complementary goals: a muscle pump powered by nitric oxide and support for the natural, pulsatile secretion of growth hormone from the pituitary gland. Below is a description of the composition and each asset separately.

Composition for 1 ml of solution

Form: sterile, clear solution for intramuscular injection in a multi-dose vial (volume according to the label, typically 10 ml). Each batch covered by a certificate of analysis (COA) confirming the content and purity of all five amino acids. The ingredients themselves come from the same family of compounds as the oral ones amino acids in capsules – the difference is the route of administration, which completely changes the pharmacokinetics.

L-arginine – nitric oxide substrate and the core of the GH amino-stack

L-arginine is an amino acid that plays a dual role in this formula. First of all, it is direct substrate of nitric oxide synthase (NOS) — an enzyme that converts arginine into nitric oxide and citrulline. It is literally the raw material from which the body produces the molecule responsible for vasodilation and the pump.

Bode-Böger et al. (1998) demonstrated that intravenous administration of L-arginine induces measurable dose-dependent vasodilation in humans – supporting a direct arginine → NO → blood flow relationship. Secondly, arginine is the historical core amino-stack stimulating the secretion of growth hormone. Kanaley (2008), in a review on arginine and exercise, describes that arginine increases resting GH secretion, possibly by inhibiting somatostatin, a hormone that normally turns down GH release from the pituitary.

It is worth adding that the nitric oxide pathway can also be influenced by the oral metabolite of arginine: those who prefer the non-injectable form will find it in the product Agmatine, which modulates NO synthase activity via a different pathway than arginine itself.

L-citrulline – a smarter way to arginine

This is where the most interesting element of the formula comes into play. Counterintuitively, if you want to increase arginine levels in your body, citrulline does this more effectively than arginine itself. The reason is pharmacokinetic: oral arginine is largely metabolized by argininase in the intestine and liver (first-pass effect) before it reaches the circulation.

Citrulline bypasses this stage – it is absorbed, goes to the kidneys and is transformed there into arginine, increasing its plasma concentration in a more predictable way. Schwedhelm et al. (2008) clearly demonstrated that oral L-citrulline increases plasma arginine concentration more effectively than an equivalent dose of L-arginine alone. Bailey et al. (2015) showed that L-citrulline supplementation improved performance parameters and enhanced NO signaling during exercise.

In EndoPump, citrulline and arginine appear together – one as an immediate substrate, the other as a “slower”, maintaining arginine reservoir.

L-ornithine – urea cycle and the second arm of GH

L-ornithine is closely related to arginine – both participate in urea cycle, a metabolic pathway that removes ammonia from the body. During intense exercise, ammonia builds up as a byproduct of amino acid metabolism and contributes to the feeling of fatigue. Ornithine supports the efficiency of this cycle, which is sometimes associated with delaying fatigue.

The second role of ornithine is its participation in the GH amino-stack. Chromiak and Antonio (2002), in a review devoted to the use of amino acids as growth hormone-releasing factors by athletes, list arginine, ornithine and lysine as the classic trio tested for stimulation of GH secretion. It is this combination that is the historical foundation of the “amino-stack for growth hormone”.

L-lysine – synergy with arginine

L-lysine is an exogenous amino acid (the body cannot produce it on its own), which in the context of this formula serves as a synergistic partner for arginine in GH stimulation. In older sports literature, the combination of arginine and lysine was tested for a stronger effect on growth hormone secretion than either amino acid alone. Chromiak and Antonio (2002) discuss this pair in the context of attempts to increase resting GH. Lysine also participates in the synthesis of collagen and carnitine, which involves the regeneration of connective tissue.

Glycine – the smallest amino acid, many functions

Glycine is the simplest amino acid that performs a function in the body inhibitory neurotransmitter in the central nervous system, but also a building block with a wide range of applications. It is a precursor of creatine (together with arginine and methionine) and the main amino acid of collagen – a protein that builds tendons, ligaments and skin. In the EndoPump formula, glycine (25 mg/ml) supports the regeneration of connective tissue and creatine synthesis, complementing the profile of the other four amino acids.

The operation of EndoPump is based on two overlapping axes, which share some of the ingredients but lead to different physiological effects. Therefore, two complementary pathways operate in one vial, not a single mechanism.

Nitric oxide axis – muscle pump

The heart of the “pump” effect is nitric oxide. The trail is simple and well described: L-arginine is a substrate of nitric oxide synthase (NOS), which converts it into nitric oxide (NO), a gaseous signaling molecule with a short lifetime. NO diffuses into the smooth muscle of blood vessels and triggers the vasodilation pathway: the vessels widen, the resistance decreases, and the blood flow through the working muscle increases.

The effect is an increase in the volume of muscle cells and the inflow of plasma – i.e. the pump. The role of arginine is strengthened by citrulline. Because citrulline increases plasma arginine concentration more effectively than arginine alone (Schwedhelm et al. 2008), the combination of both amino acids gives higher and more sustained arginine pool available for NO synthase.

Arginine provides an immediate substrate, citrulline maintains its availability over time. In practice: stronger and longer vasodilation effect than with arginine alone.

Amino-stack axis – stimulation of growth hormone secretion

The second axis is classic amino-stack GH: arginine plus ornithine plus lysine. Growth hormone is secreted by the pituitary gland in impulses, and its release is inhibited by somatostatin. Arginine (and, to a lesser extent, ornithine and lysine) probably suppresses somatostatin, taking the brake off the pituitary cell and allowing for a higher resting GH release.

Kanaley (2008) describes this mechanism for arginine, and Chromiak and Antonio (2002) discuss all three amino acids as GH-releasing factors studied in athletes. It is worth being honest about the strength of the evidence: amino acid GH stimulation is real, but its scale can be moderate and depends on the dose, route of administration and individual response.

The injectable form bypasses the limitations of intestinal absorption, which theoretically favors higher availability of amino acids for this mechanism – although most of the cited literature concerns oral or intravenous administration.

Ammonia removal and regeneration

The third, complementary thread is urea cycle. Ornithine and arginine participate in the removal of ammonia – a by-product of amino acid metabolism, which builds up during exercise and promotes fatigue. Support for this pathway is sometimes associated with delaying the feeling of fatigue during longer sessions. Glycine completes the profile from the structural side – as a precursor of creatine and the main amino acid of collagen, it supports the regeneration of connective tissue.

Bioavailability of intramuscular injection

The main argument for the injection form is: bioavailability close to 100%. Oral arginine is largely lost in the first-pass effect (intestine, liver, argininase), so the actual fraction reaching the circulation is low and variable. Intramuscular injection bypasses the gastrointestinal tract and hepatic first-pass metabolism – almost all of the amino acids enter the general circulation. This is the main pharmacokinetic advantage of this route of administration over the oral form.

• Bioavailability: close to 100% for intramuscular administration – amino acids bypass the effect of the first pass through the liver and intestinal argininase, unlike the oral form, where the bioavailability of arginine may be limited and variable
• Absorption from muscle: low molecular weight amino acids are absorbed from the intramuscular deposit into the circulation relatively quickly; the pace depends on the blood supply to the muscle (a heated muscle absorbs it faster)
• Time to pump effect: the increase in arginine availability for NO synthase occurs within several dozen minutes of administration – hence the typical use before training
• Citrulline as a reservoir: the conversion of citrulline to arginine in the kidney maintains plasma arginine concentrations longer than arginine itself, extending the window of NO activity (Schwedhelm et al. 2008)
• Metabolism and elimination: amino acids enter natural metabolic pathways (urea cycle, protein synthesis, nitrogen pool); the excess is removed mainly renal in the form of urea

The form of intramuscular injection is a deliberate choice here: its purpose is to bypass the bottleneck for arginine, which is intestinal absorption and first-pass metabolism.

The following protocol describes how an injectable amino acid mixture is sometimes used by advanced athletes who assess their risk on their own. This is not a medical recommendation. The guiding principle for every injection is: sterility and tolerance assessment before working dose.

• Starting dose (tolerance assessment): first try always 1 ml intramuscularly. The aim is to check the individual’s reaction – primarily the tolerance to pressure drop (NO dilates the vessels) and the reaction at the injection site. It’s not about the effect, it’s about safety.
• Standard dose: 1–3 ml intramuscularly before training (typically 30–45 minutes before the session), depending on tolerance and body weight. This is the range where the pump and amino acid support profiles dominate.
• Maximum dose per session: 2–3 ml. Escalation beyond this range does not proportionally increase the effect, but increases the risk of pressure drop and volumetric load on the tissue at the injection site.
• Rotation of injection sites: change the injection site with each administration (alternate deltoid, gluteal, quadriceps femoris). Repeating injections in the same place promotes fibrosis, pain and the formation of nodules. Rotation is the basic principle of intramuscular injection hygiene.
• Sterile technique: disinfection of the vial stopper and skin with isopropyl alcohol, sterile needle and disposable syringe for each administration, aspiration before injection according to the intramuscular technique. The multidose vial requires sterility with each withdrawal.
• Serving time: Due to the NO profile and pump logic, the preparation is used before training. Administration on an empty stomach or between meals is sometimes preferred for the amino acid GH axis (a meal rich in carbohydrates may suppress the GH release).

SCIENTIFIC PERSPECTIVE

Most data on amino acid stimulation of growth hormone secretion come from studies on oral or intravenous administration (Chromiak and Antonio 2002; Kanaley 2008), and data on citrulline and performance – from studies on oral supplementation (Bailey et al. 2015). The intramuscular injection profile of this particular mixture has not been the subject of large, controlled clinical trials.

The mechanisms of NO and the GH amino-stack are well described, but the scale of the effect in a specific person is difficult to predict – mechanistic optimism is worth balancing with realism about the strength of the evidence and individual variability of the response.

EndoPump has a real risk profile resulting from both its composition (nitric oxide dilates vessels) and the route of administration (intramuscular injection). The following rules are non-negotiable.

Composition-related risk profile

• Drop in blood pressure (hypotension): nitric oxide dilates vessels, which may lower blood pressure – especially at higher doses or in people with low baseline blood pressure. Symptoms include dizziness, lightheadedness and weakness. Hence the 1 ml starting dose rule.
• Interaction with blood pressure medications: Combining with antihypertensive drugs (including PDE5 inhibitors such as sildenafil, antihypertensive drugs, nitrates) may intensify the drop in blood pressure. This is a contraindication to unsupervised connection.
• Herpes reactivation (HSV): arginine is a substrate for herpes virus replication – in people susceptible to herpes recurrences (HSV), high doses of arginine may promote the activation of lesions. People with recurrent herpes should exercise caution.
• Caution in people with coronary artery disease (UAE): in people with ischemic heart disease and unstable angina (UAE), vascular modulation requires cardiological supervision – it is not a preparation for independent use in this group.

Risk profile associated with intramuscular injection

• Pain and reaction at the injection site: intramuscular injection may cause pain, redness or temporary swelling at the injection site. Seat rotation reduces this effect.
• Risk of infection: each injection breaks the continuity of the skin. An unsterile technique may result in local infection, abscess, or – in extreme cases – systemic infection. Sterile equipment and disinfection are absolute.
• Intramuscular technique: incorrect puncture (too shallow, into a vessel, into a nerve) may result in complications. The injection should be performed by a person familiar with the intramuscular technique.

Absolute contraindications

• Pregnancy and breastfeeding
• Age under 21
• Low blood pressure (hypotension) or unsupervised use of blood pressure lowering medications
• Ischemic heart disease, unstable angina (UAE), severe arrhythmia – without cardiac supervision
• Recurrent herpes (HSV) in the active phase – caution with arginine
• Renal or liver failure (amino acid metabolism and elimination)
• Lack of ability to perform sterile intramuscular injection

EndoPump status is specific because it combines permitted ingredients (amino acids) with a form of administration that goes beyond the framework of a dietary supplement (injection).

• Ingredients – Permitted Orally: all five amino acids (L-arginine, L-ornithine, L-citrulline, L-lysine, glycine) are approved by EFSA as ingredients oral dietary supplement and is commonly found in food products. The particles themselves do not raise regulatory concerns.
• Injection form – outside the supplement frame: A dietary supplement in the legal sense is a food intended for consumption (orally). Solution for intramuscular injection does not meet this definition – a product administered parenterally is not a dietary supplement in the Polish and EU legal sense. For this reason, we classify EndoPump as specialist sports preparation for adults (21+), for self-assessment of risk – not as a dietary supplement.
• GIS/EFSA: although amino acids are among the permitted ingredients of oral supplements (EFSA authorization, food regulations), the injectable form does not fall into the category of dietary supplement supervised by the Chief Sanitary Inspectorate (GIS). The preparation functions outside the framework of a food supplement.

WADA – METHOD M2.2 (chemical and physical manipulation)

Only amino acids contained in EndoPump are not listed on the WADA prohibited substances list. But intravenous injections and/or infusions in volumes exceeding 100 ml in a 12-hour period are prohibited as method M2.2 (Chemical and Physical Manipulation) except when administered during hospitalization, surgery or clinical diagnosis. Single intramuscular injections of 1-3 ml are well below this threshold and do not violate M2.2 on a volume basis – however, registered athletes (ADAMS) must monitor the total volume of all injections within the 12-hour window and check the current WADA list and regulations before making any decision. Method status and volume thresholds may change in subsequent updates.

The preparation is intended only for adults (21+) to independently assess the risk. Communication of the product as a medicine, as a dietary supplement or as a means of “guaranteeing” weight gain or the secretion of growth hormone is unacceptable.

EndoPump it injectable mixture of five amino acids (L-arginine 50 mg, L-ornithine 50 mg, L-citrulline 50 mg, L-lysine 50 mg, glycine 25 mg – total 225 mg/ml) in a sterile solution for intramuscular administration, designed around two complementary axes. The nitric oxide axis (arginine as a NO synthase substrate plus citrulline as a smarter arginine precursor bypassing the first-pass effect) drives vasodilation, blood flow and muscle pump (Bode-Böger et al. 1998; Schwedhelm et al. 2008; Bailey et al. 2015).

GH amino stack axis (arginine plus ornithine plus lysine) supports resting growth hormone secretion, possibly by suppressing somatostatin (Chromiak and Antonio 2002; Kanaley 2008). The injection form gives bioavailability close to 100%, bypassing the bottleneck of arginine intestinal absorption. This preparation is a 225 mg/ml solution, HPLC purity, sterility control, COA per batch – a specialized sports preparation for adults (21+), not a dietary supplement. Single injections of 1–3 ml are below the WADA M2.2 threshold, but the total injection volume should be monitored.

1. Schwedhelm E, Maas R, Freese R, Jung D, Lukacs Z, Jambrecina A, et al. (2008). Pharmacokinetic and pharmacodynamic properties of oral L-citrulline and L-arginine: impact on nitric oxide metabolism. PubMed
2. Bode-Böger SM, Böger RH, Galland A, Tsikas D, Frölich JC (1998). L-arginine-induced vasodilation in healthy humans: pharmacokinetic-pharmacodynamic relationship. PubMed
3. Chromiak JA, Antonio J (2002). Use of amino acids as growth hormone-releasing agents by athletes. PubMed
4. Kanaley, J. A. (2008). Growth hormone, arginine and exercise. PubMed
5. Bailey SJ, Blackwell JR, Lord T, Vanhatalo A, Winyard PG, Jones AM (2015). L-citrulline supplementation improves O2 uptake kinetics and high-intensity exercise performance in humans. PubMed

Specialized sports preparation for adults (21+). EndoPump in the Pro-Body catalog is a sterile amino acid solution for intramuscular injection and is not a dietary supplement or a medicinal product in the Polish and EU legal sense. Intended for adults (21+) only, for self-assessment of risk. Intravenous injections/infusions above 100 ml in a 12-hour period are prohibited by WADA as Method M2.2 – Registered Athletes (ADAMS) must monitor total injection volumes and check current WADA regulations before any decision.

The information in the description is educational and scientific in nature and refers to the mechanisms and results reported in the literature – it does not constitute medical advice or administration instructions.