To answer your OP...it is because you do not need testosterone to build muscle.
As far as oral only cycles go, you will get your best results using a combination of orals and injectables 'primarily' because injectables (for the most part) are non-toxic, which allows you to use more total mg of steroid for a longer period of time. Orals, due to toxicity, are more limited in both total dose and duration of use, although the toxicity claims are almost always severely exagerated.
With that said, can you make good gains with orals alone? Of course you can, especially as a beginner. Do I recommend it? Not normally, no, but is there a rule against it? No. Here's the bottom line. You can use orals only for quite a while and make great gains. In fact, some of our most potent steroids are orals; capable of adding 12-20 solid pounds in 30 days (think SD). Most guys could alos run these oral only cycles for many years without experiencing any serious liver issues, assuming they exhibit some common sense. However, an over-dependence on orals for a long period of time significantly increases your risk of cardiovascular health problems. This is no big deal if it is only done for a couple of years (assuming no pre-existing conditions are present), but if you continue to use these oral only cycles frequently for 5, 10, 15 years, it is going to be difficult to avoid cardiovascular health problem, simply because most orals severely alter your lipid profile. Most people cannot go 10-15 years with fucked lipids and not have consequences.
We hear all the time how it is not possible to make good and/or lasting gains with orals alone, but the truth is that this is straight up horseshit. Most of the guys who deny this are those who are either repeating what they heard from someon else...who in turn heard this from someone else...who in turn heard this from someone else, etc...and the cycle perpetuates itself. Or...it comes from guys who view this claim from the wrong prespective. It is true that some orals result in a large amount of weight loss post-cycle, but this does not mean that these orals result in a faster rate of post-cycle muscle fiber loss, as bodyweight gains and muscle fiber gains are two very different things. However, when someone loses a lot of bodyweight post-cycle, the person often assumes that they also lost a greater percentage of muscle fiber compared to a steroid that results in minimal bodyweight loss, but this is not the case. The ONLY reason bodyweight loss can flucuate so greatly between the different steroids is because of varying degrees of water retention...both intramuscular and sub-q water retention. Some steroids result ina LOT of intramuscular water retention, but intramuscular water retention can be VERY decieving, as I.M. water is indistinguishable from genuine muscle fiber. Therefore, when an indivoidual goes off of a steroid like Anadrol and loses 8-10 lbs of IM water, it will look like he lost 8-10 pounds of genuine muscle. In reality, actual muscle fiber will be lost at the same rate with any steroid post-cycle. Below I copy & pasted a quote of mine from another boartd, which I posted as a retort to someone who said different steroids result in different rates of gains (muscle fiber) retention.
"Post-cycle muscle retention is dependent on a single factor...your body's natural hormonal environment relative to its genetic capacity to hold muscle tissue. It does not matter what drugs you used to gain muscle fiber or the rate at which you gained that muscle fiber. Before I address the issue of muscle fiber retention, I want to address the issue of bodyweight retention, as these are two very different things. We often hear that it is more difficult to miantain gains with some steroids compared to others, but this is 100% hogshit. In reality, all steroids offer the same degree of muscle fiber retention, but can vary considerably in terms of bodyweight retention. This is because weight gains are not necessarily indicative of muscle fiber gains. Steroids can cause weight gain through multiple mechanims, such as intramuscular (IM) water retention, sub-q water retention, increased blood volume, muscle fiber growth, etc. So, just because someone might gain 20 lbs in 4 weeks with a certain steroid, it does not mean they gained 20 lbs of muscle. Most people understand this, but they make the mistake of attempting to assess the amount of muscle fiber they gained by looking at their level of sub-q water retention. They figure that if they are holding little to no additional sub-q water, that the majority of their bodyweight gains are muscle fiber. This is a big mistake, as I.M water retention is not visisble and could make up a very large portion of their bodyweight gains, depending in the steroid used. For example, Anadrol causes a very large amount of IM water retention by inhibiting the 11-beta hydroxylase enzyme, so when someone uses Anadrol, they will usualy gain a large amount of bodyweight very quickly...within just 2 weeks. However, when the person goes off of Anadrol, they lose all of this IM water weight just as fast, as well as any sub-q water weight they gained. This is why people lose bodyweight so quickly when going off of Anadrol. It is not because they lose muscle fiber more quickly than with other steroids...it is only because the body is no longer being ordered to hold a ton of IM water. With a drug like Primo, there is very, very little IM water retention...and no sub-q water retention. It also causes a significantly smaller increase in blood volume than Anadrol. Therefore, when the user stops taking primo, they lose very little bodyweight. This leads people to belive that Primo has a high rate of muscle fiber retention. In reality, both result in the same rate of post-cycle muscle fiber retention; the only differences between the two is in the total amount of water retention (both IM & sub-q) expereinced when on-cycle with each steroid.
Moving onto the subject of long-term muscle fiber retention, it has NOTHING to do with what kind of steroids are used or how quickly muscle is gained. It comes down to one thing...how much muscle a person currently holds relative to their natural genetic limit, which is largely dependent on their nartural hormonal environment.
As soon as someone hits their natural genetic limit in terms of muscle mass, they will NEVER be able to maintain one ounce of muscle beyond that point without the assisatnce of steroids. Sure, they might be able to take steroids and gain 30 more pounds of muscle fiber, but as soon as they go back off steroids, they will eventually lose every single ounce of muscle they gained if they stay off steroids long enough...until they go back down to their natural genetic limit. On the flips side, if someone is still 40 lbs away from their natural genetic limit and they gain 30 pounds of actual muscle fiber with steroids, they will be able to maintain all that new muscle naturally, even if they permanently go off steroids....assuming they eat enough to maintain the newly built muscle. This is because they were still 40 pounds away from what they could have gained & maintained naturally. Their natural hormonal environment was still capable of adding & maintaining another 40 pounds of muscle fiber. With steroids, we super-charge our hormonal environment, allowing us to build and maintain much more muscle than what we can achieve naturally. It does not matter how long it takes us to build muscle fiber...or what steroids we use to build it....we will ONLY maintain it IF we have a hormonal environment capable of supporting it...period. This is why pro BB'rs must permanently stay on a large amount of AAS if they want to maintain their size...and also why they lose muscle so rapidly if they go completely off. Maintaining ther pro-level mass requires high anabolic demands.
So, if someone gains 15 pounds of muscle fiber using Primo for 30 weeks, it will not be any easier or harder to maintain that muscle fiber than someone who built 15 pounds of muscle over 8 weeks of Anadrol use. Muscle fiber is muscle fiber...and gains retention doesn't change based on steriod selection of length use....only bodyweight retention does based on IM & sub-q water retention (as well as a few other factors which make up a relatively small percentage of one's bodyweight gains). Alow me to give you a personal example. I have personally gained 18 pounds in 30 days when using 30 mg of SD...and I have also gained 18 pounds over 8 weeks when using test & deca. However, I lost nearly half my bodyweight wihe I stopped the test & deac cycle, but I only lost 4 lbs when I went off the SD. This has nothing to do with one steroid providing better gains retention. I kept more weight with SD simply because a larger percentage of the bodyweight I gained was pure muscle fiber. So, gains retention (which means muscle fiber retention) was the same with both cycles....the test & deca simply added more water, so I lost more weight post-cycle...but the legitimate muscle fiber I gained on that cycle was maintained/lost at the same rate. This lesson is often hard to lean for beginners...because all they see is how much muscle size they 'appear' to lose, not how much was actually lost. Of course, as stated earlier, whether or not this muscle fiber is permamntly maintained will depend on whether or not the person's natural hormonal environment is capable of supporting this newly gained muscle fiber. If it is not, they have two options. they can either stay off steroids until they eventually lose it all...or they can go back on before they lose it all."
As you can see, it does not matter whether one uses orals or injectables, as far as post-cycle muscle fiber gains retention rate goes. If we broke all this down into 3 easy to understand statements, it would go like this:
Rate of post-cycle bodyweight retention: Dependent on how much water was added on-cycle.
Rate of post-cycle muscle fiber retention: The same for every steroid.
Permanent post-cycle muscle fiber retention: Dependent on your body's natural hormonal environment relative to its genetic capacity to hold muscle tissue.
So, you can use orals alone and gain quite a bit of muscle fiber, but as soon as you surpass your natural genetic limit (ie. the amount of muscle fiber one can maintain without additional anabolic assistance), you will lose every bit of muscle fiber you gained beyond that point after you discontinue the drugs. The rate at which you will lose this muscle fiber is dependent on many factors and outside the scope of this post.
In the end, I don't have any problem with someone who decides to take the oral-only route. After all, it is their fucking body, so as long as they remain safe there is nothing wrong with it...but should they reach a point in their development where they need to compromise their health in order to keep making gains and they decide to do so anyway, I wholly disapprove. Lastly, we should all remember that not everyone who uses steroids is a BB'r. For a competitive BB'r who is plannng on using steroid for 10-20 years, while trying to maximize his development, oral-only cycles would obviously be a horrible choice. But...for the guy who just wants to gain 20 pounds of muscle while shedding some bodyfat...or the athlete who wants to improve his performance a bit during the competitive season, orals can potentially meet their needs perfectly well.
anyways im on creatine.
