As a personal trainer and a judge for National Physique Committee bodybuilding events, Dr. Bruce Nadler has seen his share of bulging biceps, massive pecs and delts that might make a Greek god hang his head in shame.
But he said that what he has seen on the professional bodybuilding circuit in recent years takes the cake.
"When I go to the bodybuilding performances now, some of them, their appearance is barely human," he said.
So what's behind the 30-inch biceps and the other freakishly proportioned muscle groups on display nowadays?
The culprit is a type of injectable oil, commonly known as synthol.
Bodybuilder and fitness author Ron Harris said that synthol and products like it are used only by "a very small percentage of bodybuilders, but they tend to really stand out."
"They are just obnoxious to behold," he said.
And Nadler said that the practice has gotten way out of hand.
"There are some instances of absolutely freakish appearance because of it," he said. "The fact that a lot of individuals have this bizarre appearance shows that there is an attraction there, even if it is the same type of attraction you'd see at a bad car wreck."
Invented in the mid-1990s by a German bodybuilder named Chris Clark, synthol is a thick oil that is usually injected directly into the "belly" of a muscle to literally pump it up -- albeit temporarily.
Competitive bodybuilders originally used synthol and other products like it, known collectively as site enhancement oils, to even out minor asymmetries in muscle size and shape.
But before long, some bodybuilders began injecting massive quantities of the oil into their arms in order to appear more buff -- a practice known in the sport as "fluffing."
"It makes the muscle appear larger, but it actually weakens it," said Dr. Mauro DiPasquale, a former bodybuilder and physician in Ontario, Canada, and president of the United World Powerlifting Federation.
In this way, synthol is not the same as steroids. While steroids are hormones that help increase the actual muscle size and mass, synthol is a bit like an implant for the arms; it just makes muscle look bigger.
However, Harris said, "The same mentality that would drive people to use steroids would drive them to this."
But in bodybuilding, being artificial isn't always perceived as a bad thing. As a former cosmetic surgeon whose services were sought out by a number of bodybuilders, Nadler said he has used medical aesthetic procedures to help some patients increase the apparent size of certain muscles -- from calf implants to pectoral implants.
But he said that in most cases the abuse of synthol leaves much to be desired in terms of appearance.
"It is used and abused today in everything from filling muscles to making muscles look like big bags of oil," he said.
Harris agrees. "You get weird lumps and bumps, as well as an almost bizarre shape to the muscle."
That doesn't deter some competitive bodybuilders, who see the shots as a shortcut to massive gains.
"I've heard of one person who had 150 synthol injections into one muscle area," DiPasquale said. "I've seen people who have tried to pump their 19-inch arms up to 22-inch arms."