This is also incorrect. http://jap.physiology.org/cgi/content/full/102/2/740 (This study) examined clen's mechanism of action. It's worth noting that early in the paper they state that "CHRONIC ADMINISTRATION OF clenbuterol and other synthetic compounds that activate beta-adrenergic receptors has been shown to induce skeletal muscle growth in multiple mammalian species, including rats, cows, sheep, pigs, and humans." Just like I said before, this is a feature of beta-agonists generally (including clen, albuterol, metaproterenol, etc), in humans.
The study found that clen not only increases muscle mass through the well established cAMP -> PKA pathway, but also the PI3K -> Akt -> mTOR pathway. To say that "no one really knows for sure" how clen promotes skeletal muscle anabolism is incorrect. While you can play semantic games over what it means to "know for sure", there's no question that researches have a very good understanding of the pathways that clen operates through.
Not so fast. Clen produces minimal to zero effects according to who? You? Sorry, but the human studies I already posted contradict that. Also, keep in mind that most bodybuilders take clen while dieting, an environment where muscle loss is the norm. They're in a poor position to assess the anabolic/anti-catabolic effects of clen when a positive result would likely manifest itself as a slowing of muscle loss. Ask yourself how easy is it to quantify that, let alone identify it. Even if bodybuilders did take clen while bulking, it's laughable to think that an individual would be in any position to assess the extent of clen's additive effect with nothing more than uncontrolled anecdote.
You can be obstinate and hold the thought for as long as you want. You can ignorantly keep asserting that there are no human studies, that no one knows what the mechanism of action is. I can see you're eager to stay ignorant, so be my guest.
First of all, the study you mention is in rats. Terminator, while we can both go round and round about rats studies vs humans, just let it be known that many studies which seem excellent in rats, when it comes to humans, its not more as clear cut. A perfect example is w/ the studies involving the hormone "resistin" in mice almost a decade ago. Researchers thought they found exactly what causes insulin resistance, but still now they are debate whether resistin may even cause a negative effect, neutral, or even possibly a positive effect in regards to insulin function in the human body.
So, back to the study you give. Govenor, Idk if you actually read the WHOLE STUDY, just skimmed through it, or simply read the abstract, but your previous posts contradict what you state. In the study it says verbatim... "The findings illustrate that the actions of clenbuterol are likely mediated through multiple pathways and underscore the necessity to examine multiple muscles under a variety of conditions to establish a complete understanding of clenbuterol and its mode of action. The growth and muscle-sparing effects of clenbuterol could be mediated through a single or multiple pathway(s) that affects protein synthesis or degradation processes."
...even the researchers in the study DO NOT know for sure the exact mechanism of actions that Clenbuterol has in regards to skeletal muscle, though they at least feel they know somewhat and are at least on to something.
Here is something else for you in the study, Detective John Kimbell, verbatim...
"The growth and muscle-sparing effects of clenbuterol could be mediated through a single or multiple pathway(s) that affects protein synthesis or degradation processes. The reported effects of clenbuterol and other 2-adrenergic agonists on muscle protein turnover have been contradictory (23). A number of studies utilizing radioisotopically labeled amino acids have reported increases in the fractional synthesis rates in skeletal muscles after treatment with 2-adrenergic agonists (18, 26, 29). However, other studies have found no change in protein synthesis rates (28, 35). The conflicting results could be because of differences in the muscles studied and the timing of the measurements. In general, the growth effects induced by 2-adrenergic agonists are more pronounced in predominantly fast-twitch muscle than slow-twitch muscle (18, 23, 31, 38). Increases in fractional synthesis rates have been observed at 1–3 days after the start of clenbuterol treatment, returning to normal within 7–10 days (18, 29). For example, Hesketh et al. (18) observed a 37% increase in the fractional rate of protein synthesis in the rat gastrocnemius after 1 day of clenbuterol treatment, which returned to control levels by 4 days."
...so you used the term "chronic" in relation to using Clenbuterol to gain consistent quality muscle, but if you look at how on the sentence in the last study how protein synthesis rates returned to normal after 4 days. I really don't see this as 3 days of the body trying to increase muscle mass via protein synthesis as chronic. Furthermore, study #23 supports this notion as Clenbuterol ONLY supporting muscular growth for a very short time. The link is provided below is ppl want to look at it...
Beta-adrenergic agonists and hypertrophy of skelet... [Life Sci. 1992] - PubMed result
...the study provided in the link above along with the study I have already quoted verbatim have also talked about the beta 2 agonist property of Clenbuterol only works well in "type II fast twitch". The study also gives 2 other studies that show no change in protein synthesis with the possible reason for this being differences in muscles being studied. So w/ me saying it doesn't give some ppl the results they want (zero to minimal) is correct. Also, back to the point of Clenbuterol's action on skeletal muscle fading away quickly. I guess you might say to up the dose slowly all the way to 720 micrograms like they do in the 1 study you give regarding ppl who built muscle using that much Clenbuterol. Do you SERIOUSLY consider this a study of merit pertaining to the ppl on this forum. SERIOUSLY, Conan, do you REALLY consider that safe?! Here is the link for ppl who might not believe me...
Effect of clenbuterol on cardiac and skeletal musc... [J Heart Lung Transplant. 2006] - PubMed result
,,,also here is a link to a study that contradicts using Clenbuterol for bodybuilding purposes in the first place...
Elsevier