Im gonna start off with this picture
This was accomplished by breeding cattle that have a natural genetic mutation that inhibits
myostatin. Myostatin is a hormonal muscle growth inhibitor. Several genetic mutations result in cattle with continued muscle growth in a fashion that is
hyperplasia not
hypertrophy. Hypertrophy is the "ballooning of muscle tissue" and is seen in cardiac muscle problems where the muscle cells just get bigger (and less efficient). In the hyperplasia mode, muscle cells duplicate themselves and form what are called "double muscling" . The cow, a Belgian Blue Beef Bull, is an example of the product of breeding cattle with a natural myostatin inhibitor.
(I was doing some research for a series of seminars we are team teaching next Fall and a Beef Cattle geneticist is going to be handling a seminar section that relates to Darwins own artificial selection experiments (except from a genetic knowhow POV). ANYWAY, we were seeking out information about research in myostatin inhibitor reearch (it has potential use for treatment of such diseases as MD and post polio complex). WOULD NOT YOU KNOW iT, the first test tries for some of this stuff is for PERFORMANCE ENHANCEMENT DRUGS. Because the myostatin inhibitors arrest the "shutting down" action in the body, muscle growth is speeded up and extra muscle tissue is packed on. The drug companies involved asay that this is perfectly safe and doesnt have all the side effects that anabolic steroids have (increasing testosterone has all sorts of problems in the system and drug abuse for peak muscle growth is quite common as athletes get more and more "hooked on juicing".
This class of drugs is also going to be very difficult to track and test for.
SO remember that cow up top. If we see athletes with those creepy body builds, chances are theres a new "juice" in town.