Adelphi Research Boldenone 300mg (Equipoise)

Adelphi Research Boldenone Undecylenate (Equipoise) 300mg/ml is a long-acting injectable steroid that produces steady, lean muscle gains with enhanced vascularity, increased appetite, and improved endurance. With an anabolic rating of 100 and an androgenic rating of 50, Boldenone delivers quality mass at a slower, more sustainable pace than Testosterone or Dianabol, with significantly less water retention and a lower incidence of oestrogenic side effects. Originally developed for veterinary use (hence the brand name Equipoise), it has become a staple in bodybuilding for lean bulking and endurance-enhanced training phases.

How Boldenone Works

Boldenone is a direct derivative of testosterone with a double bond at the 1-2 carbon position. This modification reduces its androgenic activity by 50% while maintaining full anabolic potency. The practical result is a compound that builds muscle with fewer androgenic side effects (less acne, less hair loss, less aggression) than testosterone at equivalent doses.

Boldenone’s most distinctive pharmacological effect is its stimulation of erythropoietin (EPO) production in the kidneys, increasing red blood cell production more potently than most other steroids. This elevated red blood cell count improves oxygen delivery to working muscles, directly enhancing cardiovascular endurance and recovery between sets. Users consistently report the ability to sustain higher training volume and intensity during Boldenone cycles.

The compound aromatises at approximately 50% the rate of testosterone, meaning it produces less oestrogen conversion and less water retention. This gives gains a leaner, drier quality compared to high-dose testosterone cycles. However, Boldenone does aromatise enough that an AI may still be needed at higher doses or when stacked with other aromatising compounds.

One frequently noted effect of Boldenone is a significant increase in appetite. For users in a bulking phase, this can be extremely beneficial as it facilitates the caloric surplus required for maximal growth. For cutting users, this appetite stimulation may be counterproductive and should be factored into compound selection.

Suggested Protocol

• Dose: 300-600mg per week
• Cycle length: 14-20 weeks (Boldenone’s undecylenate ester is very long-acting; shorter cycles do not allow the compound to reach full effect)
• Injection frequency: 2x per week for stable blood levels
• Always run with a testosterone base: Test E at 300-500mg/week
• AI if needed: Arimidex 0.25mg EOD. Many users find they need less AI with Boldenone than with equivalent doses of Testosterone
• PCT start: 21 days after last injection (long ester, similar clearance time to Deca)
• PCT: Nolvadex 40/40/20/20mg for 4-6 weeks

What to Expect

• Week 1-4: minimal visible changes. The undecylenate ester takes 4-6 weeks to build to effective blood levels
• Week 5-8: appetite increase is the first noticeable effect. Vascularity begins improving. Subtle fullness developing
• Week 9-14: steady mass accumulation becomes visible. Vascularity noticeably enhanced. Endurance and training capacity improved
• Week 15-20: peak effects. Quality, lean gains with minimal water. Expect 4-7 kg of lean mass over a full 16-20 week cycle
• Overall character: slow, steady, high-quality. Boldenone rewards patience. Users who expect Dianabol-style rapid weight gains will be disappointed; those who appreciate gradual, retainable lean mass will prefer it

Side Effects

• Elevated haematocrit: Boldenone’s strong EPO stimulation raises red blood cell count more than most steroids. Haematocrit monitoring is essential. If levels exceed 54%, consider blood donation or therapeutic phlebotomy. The UK MHRA flags haematocrit above 54% as a cardiovascular risk factor
• Anxiety: a minority of users report increased anxiety on Boldenone, possibly related to elevated haematocrit and blood viscosity. Dose-dependent
• Appetite increase: beneficial for bulking, potentially problematic for cutting
• Mild oestrogen: water retention is minimal but possible at higher doses. AI on hand recommended
• Hair loss: low risk. Androgenic rating of 50 makes it one of the more hair-safe injectables
• Testosterone suppression: full. PCT mandatory
• Liver toxicity: none (injectable)
• Very long detection time: 18+ months. Not suitable for tested athletes

Key Facts

• Active ingredient: Boldenone Undecylenate 300mg/ml
• Manufacturer: Adelphi Research
• Anabolic / Androgenic: 100 / 50
• Half-life: 14 days (undecylenate ester)
• Aromatisation: low (approximately 50% of testosterone)
• Detection time: 18+ months

Compare all injectable compounds in our Injectable vs Oral Guide. For PCT after long-ester compounds, see our PCT Guide. Browse all injectable steroids.