These days, there probably isn’t a BB’r alive that hasn’t heard of trenbolone. In today’s drug circles, it has attained nearly super-hero status as an anabolic agent. “Nectar of the gods”…“A steroid on steroids”…and “indispensable” are just some of the terms which have been used to describe this highly desirable drug. There is no single characteristic responsible for Trenbolone’s unique effects on the musculature. Rather, it is a precise combination of attributes which provide such amazing results.


There are few non-methylated drugs capable of functioning as both a mass builder and cutter, while excelling at both. In fact, if pressed to name another non-methylated drug capable of duplicating trenbolone’s performance, I would be unable. Typically, trenbolone is known for its ability to generate substantial gains in dense, dry muscle tissue; a trait which has no doubt earned it a top spot in both contest prep and off-season programs alike. Likewise, its strength building and psyche altering capabilities have made it popular among strength-power athletes, but rather than re-hash these well known traits, I want to spend a bit of time talking about some of the less publicized qualities of trenbolone.

One often debated topic in the steroid world is the role of estrogen in the muscle growth process. Up until the last decade, many BB’rs were taught to avoid the use of anti-estrogenic drugs when in the off-season, as it was commonly believed that the elevated estrogen level achieved with aromatizable drugs was necessary for maximizing muscle growth. This belief was born out of real-world experience, with many BB’rs noting a reduction in overall weight gain when administering these drugs. Were these old-school BB’rs simply confusing estrogen induced water retention with genuine muscle growth, or was there more to the story?

In recent years, the phobia surrounding anti-estrogenic drugs has greatly diminished. While science has confirmed the importance of estrogen in the growth process, most steroid users now believe that keeping levels within the low-normal range is more than sufficient to obtain all its growth benefits. To this end, aromatase inhibitors such as Aromasin and Arimidex are freely employed in the programs of today’s steroid using BB’rs. So, how does this apply to trenbolone, a non-aromatizing steroid, you might ask?

Perhaps no other segment of our society has conducted more research on the anabolic effects of trenbolone than the meat industry. In a multi-billion dollar a year business, which relies on meat yield to turn profit, improving growth rate is priority #1. This has led to the development of long-standing products such as Revalor H; a combination hormonal preparation containing trenbolone acetate and estradiol in a 10:1 ratio. Why the addition of estradiol and more so, why such a high dose? When using a normal testosterone to estrogen ratio as a baseline for comparison, this formula is grossly lopsided in favor of estrogen. Other formulas, such as Revalor S, provide an even more exaggerated ratio, with 120 mg of testosterone for every 24 mg of estradiol. That is nearly a 5:1 ratio! Why is estrogen dosed so high? The answer is quite simple—because this combination results in a greater meat yield compared to using lower doses of estrogen or no estrogen at all.

In one particular study designed to examine the relationship between trenbolone and estrogen as it pertains to IGF-1 levels, 20 feedlot steers were randomly assigned into one of 4 groups and provided with varying combinations of these drugs. There 4 groups are as follows: 1) Control (received no trenbolone or estrogen). 2) Trenbolone only. 3) Estrogen only. 4) Trenbolone + estrogen. At the onset of treatment the animals were weighed and muscle biopsies were performed. This was repeated on days 7, 14, and 28.

In animals treated with estrogen only, IGF-1 levels increased by nearly 75% in only 28 days. Somewhat surprisingly, IGF-1 readings were nearly identical in the trenbolone + estrogen group, while the trenbolone only group experienced no increase in IGF-1 levels. These results indicate that estrogen alone was entirely responsible for mediating the increase in IGF-1 seen in the trenbolone + estrogen group. While animal studies are not always directly applicable to humans, this study strongly suggests that the anabolic effects of trenbolone are further enhanced in a high estrogen environment.

We find support for this position when evaluating the real-world results of the testosterone-trenbolone stack. Despite trenbolone’s much higher anabolic rating, superior gains in muscle mass are noted when trenbolone is combined with testosterone, compared to using trenbolone alone at an equal dosage. In this case it is testosterone, rather than synthetic estrogen as utilized in the study above, which supplies the necessary estrogenic component via aromatization. Although science has yet to uncover the ideal ratio of testosterone to estrogen in muscle seeking BB’rs, it is clear that estrogen amplifies the anabolic effects of trenbolone, as well as non-aromatizing AAS in general. More research is needed in this area.

Trenbolone may also stimulate growth through enhanced proliferation and differentiation of satellite cells, which may be mediated through an increase in IGF-1 sensitivity. In order to understand why this is important, let’s first look at the role of satellite cells in the muscle growth process. After a hard training session, the muscle cell proteins within muscle fibers sustain damage, which activates a special type of stem cell known as satellite cells. These cells, which are located between the basal lamina and plasma membrane (an area directly outside the muscle fibers), are quickly shuttled to the site of injury, initiating the muscle regeneration process. They then begin to multiple (proliferate) by fusing to other satellite cells and to existing muscle fibers. A portion of these satellite cells will remain as organelles, but the majority will differentiate (the process of turning immature stem cells into mature muscle cells) and fuse to muscle fibers, either creating new muscle protein stands (myofibrils) or helping to repair previously damaged muscle fiber. The formation of these myofibrils (muscle fibers) directly leads to an overall increase in the size of the muscle.

This muscle repair process is aided by numerous growth factors, such as testosterone, growth hormone, insulin, IGF-1, HGF, and FGF. These hormones influence the rate and amount of protein that is deposited in the muscle during the repair process, with higher levels speeding up the muscle growth process and lower levels slowing down the process. In particular, IGF-1 and FGF have a direct influence on the proliferative response of satellite cells. In multiple studies, trenbolone has been shown to enhance this proliferative response, which the researchers suggest is due to trenbolone’s ability to increase satellite cell sensitivity to IGF-1.

This research further supports the notion that trenbolone should be used in a high estrogen environment, as trenbolone’s likely ability increase satellite cell sensitivity to IGF-1 cannot be fully capitalized on without the additional increase in IGF-1 that only estrogen can provide. Together, trenbolone and estrogen work synergistically to promote an increased hypertrophic response.

One of the most prized benefits of trenbolone is its ability to provide a hard, dense look to the muscles. This look is partially attributable to the reduction in subcutaneous water which accompanies trenbolone use, which many refer to as a ‘drying-out’ effect. Generally speaking, this reduction in sub-q water levels takes place relatively quickly–just 1-2 weeks, after which point water levels are maintained as long as trenbolone remains part of the program. However, many trenbolone users have noted an additional increase in muscle hardness and density which seems to take place in the months following this initial drying out phase.

One possible explanation for this effect is trenbolone’s ability to protect against intramuscular fat accumulation. While certain androgens, such as trenbolone and Oxandrolone, have been to shown to reduce visceral, as well as subcutaneous bodyfat levels, the potential for intramuscular fat reduction is less often discussed. In studies involving cattle, trenbolone has been shown to reduce intramuscular fat stores to a significantly greater degree than the control group. While there is no evidence demonstrating a connection between muscle composition (the proportion of I.M. fat to muscle fiber) and visual appearance, such a suggestion is not unreasonable.

Muscle density is very closely associated with muscle hardness and in reality, the two terms are almost interchangeable, but there is a slightly different quality associated with muscle density that is somewhat difficult to explain. A dense muscle, in addition to displaying a hard appearance, appears as if the muscle fibers themselves are packed tightly together with no room left between them. The biceps of Lee Priest or Ronnie Coleman, when in competition shape, are excellent examples. Although heavy training has often been implicated in the creation of muscle density, heavy training alone, even when bodyfat and sub-q water are reduced to competition levels, does not guarantee muscle density. In fact, this effect can only be maximized through proper steroid selection and few steroids accomplish this better than trenbolone. Could it be that trenbolone, through its ability to alter muscle composition more profoundly than most other steroids, is partially responsible for the dense appearance it provides?

Another benefit associated with trenbolone is its nutrient repartitioning effect. A nutrient repartitioner is any substance which promotes the preferential use of nutrients for protein synthesis and glycogen restoration over the storage of adipose tissue. In other words, the food you eat is more likely to be used for muscle growth and less likely to be stored as fat. This nutrient repartitioning effect has a direct effect on food efficiency, as demonstrated in the study below.

In an attempt to determine how effective trenbolone was for increasing food efficiency in cattle, 72 steers were separated into three groups of 24 according to breed, while controlling for food intake throughout. After slaughter, the carcasses were evaluated for net gain and feed efficiency, with treated steers showing an average increase of 17%, 26%, and 21%. Although food intake remained consistent between the treated and non-treated steers, lean mass increased substantially in the treated group. It is one thing to gain muscle when consuming a surplus of calories, but it is quite another to gain muscle on a number of calories that would normally be reserved for maintenance.

Trenbolone’s potent re-comping effect is a great example of this in the real-world, with many users claiming unrivaled results in this area. I can personally testify to this in my own life. There may be steroids that get you bigger and/or stronger, but nothing changes the body as comprehensively and quickly as trenbolone.

Trenbolone is a complex steroid, having dozens of internal effects on our physiology. Many of them play a positive role in terms of physique & performance enhancement, but are largely unrecognized by the BB’ing community as a whole. In this article we touched on a few of these, which hopefully, has wetted your appetite for additional information on the subject.