The mystery substance found in the home of Oscar Pistorious after the shooting death of girlfriend Reeva Steenkamp has been identified as Testis compositum.

Representatives for the Olympic champion known as the "Blade Runner" said the substance is used in the "in aid of muscle recovery," but similar products have been marketed as testosterone boosters and sexual supplements.

Police originally identified the substance as testosterone when they found it — along with needles — in the house Pistorius shared with Steenkamp.

So what exactly is Testis compositum, and what effect would it have on the human body?

Ben Greenfield, an expert in fitness, nutrition and sports science, explains that Testis compositum is a blend of "purported testosterone enhancing compounds like pig testicles, heart, embryo and adrenal gland," and can also contain ingredients such as cortisone, ginseng and other herbs, botanicals and minerals.

“What I think is the most interesting part is the name itself," adds Dr. Steven Lamm, the director of men's health at New York University's School of Medicine. "There’s something just strange about the name [Testis compositum]. It obviously implies it aids with testosterone production," he says. But in homeopathic doses, as Testis compositum is often found, "the likelihood that this could stimulate testosterone production is extremely low,” believes Lamm.

Greenfield agrees. "The stuff can help with sexual performance and also can help you feel a little better if you have very low testosterone, but you'd actually have to take enormous quantities of something like Testis compositum to get a significant performance-enhancing effect."

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“It’s not a banned substance either, which I thought was interesting,” noted Dr. Lamm. “The fact that [the Olympic Committee] didn’t appear to have any problems with the substance tells me that it doesn’t do anything.”

However, the use of Testis compositum may be indicative of something more serious, says Ben Greenfield. "In reality, most athletes use this [Testis compositum] as a 'cover up' for use of the stuff that really works: bioidentical testosterone and DHEA creams, lotions and injections."

And as for the needles found in Pistorius' home? "At least in America — I don't know how it is in other countries — you can't, as a consumer, buy anything over the counter that is injectable," says Lamm, although he asserts that, as a doctor, he would never make assumptions about their actual purpose. "Everyone's medical needs are different," Lamm says.

But both Greenfield and Lamm seem to agree that Testis compusitum would have little effect on an athlete, if any.

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"The implication is that somehow, this will stimulate a person’s testosterone,” Lamm continues. “But an Olympic class athlete, their testosterone, 99.9 percent of the time, is completely normal," he says, explaining that often times, low testosterone is a symptom of men with poor health. "If I’m looking at a conditioned athlete, with 10 percent body fat, the likelihood they have low testosterone is zero."

Lamm also dismisses the notion of Testis compositum somehow having an effect on Pistorius the night of the murder. "No matter what medication, they'll always try to connect it to something," he says, referring to the media. “I doubt if there’s much substance to this."