The Pittsburgh Pirates were dealt a big blow Tuesday as center fielder Starling Marte was suspended 80 games after testing positive for a performance-enhancing drug. The club will miss him in the lineup and in the field, and should the Pirates qualify for the postseason, Marte will be ineligible to play.

Marte tested positive for a substance called Nandrolone, according to MLB's press release. In a statement, Marte said "neglect and a lack of knowledge" led to failed drug test, indicating he unknowingly took the substance. So many players have used that defense over the years that it's impossible to tell who is being sincere and who is making up excuses.

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Starlin Marte tested positive for a performance enhancing drug. USATSI

Here is what we know about Nandrolone, the substance found in Marte's system.

1. It is typically injected

Generally speaking, Nandrolone is an injection-only substance, which would undermine Marte's "neglect and a lack of a knowledge" defense. However, tests can find Nandrolone in other substances taken orally.

2. It is an old school steroid

Nandrolone is not a trendy new state-of-the-art performance-enhancer. It has been around since 1960s and was first banned in Olympic competition in 1974. This is very much an old school substance, not something designed to beat current tests.

3. It promotes things that would sure seem to help a baseball player

Among the benefits of Nandrolone are increased muscle growth, increased bone density, increased red blood cell production and increased appetite. That all sounds very beneficial to a baseball player, especially one looking for ways to increase strength and also improve recovery so they can stay on the field.

4. It still has some medical uses

Nandrolone does have some medical uses, though it is not used as often as it once was. Among other uses, it is typically used to promote healing for patients with cancer, AIDS or severe burns. It it is also used to treat anemia caused by kidney failure.

5. It has some side effects.

Among the side effects of Nandrolone are cardiovascular damage and erectile dysfunction.