Athletes want to be bigger and stronger, and steroids tell the body to build more muscle. Bodybuilders have known that for decades. But scientists, who prefer exercising their minds to flexing their biceps, have long been skeptical.
In recent years, though, evidence of steroid effectiveness has been accumulating, and not just from home-run statistics. Science has begun to figure out why steroids are so popular, along with some reasons why maybe they shouldn't be.
The steroids at issue here are "anabolic" steroids, those that build muscle or other body tissue. Dozens of anabolic steroids have been manufactured, all molecular variants of the male sex hormone testosterone.
In addition to being anabolic, such steroids are also at least somewhat "androgenic," or masculinizing, which is why women athletes who take steroids risk growing beards.
For years, science doubted that steroids actually built strong bodies any better than Wonder Bread. But that doubt was based on studies of much smaller doses than your typical anabolic-built athlete takes.
Most of the research was done on men taking small clinical doses of steroids to counteract a testosterone deficit, or to compensate for a body-wasting disease (such as AIDS).
Higher doses shouldn't matter, scientists believed, because a normal body's steroid-sensing molecules (known as androgen receptors) should be saturated even at low doses. Adding more steroids to an athlete's drug diet might seem to work, scientists suspected, only because a steroid-induced euphoria encouraged spending more hours lifting weights.
Apparently, though, athletes knew their drugs better than scientists did. It now appears that taking mega-doses of steroids induces the body to produce more androgen receptors. Stimulated androgen receptors then tell cells to fire up their factories to produce more muscle-tissue protein (and perhaps also interfere with muscle tissue breakdown). Even men who exercise little can build muscles simply by using steroids.
Since 1990, when anabolic steroids became illicit "controlled substances," steroid use seems to have increased, Dr. Nick Evans of the UCLA-Orthopaedic Hospital in Los Angeles reports in the current issue of The American Journal of Sports Medicine.
Studies indicate that as many as 30 percent of gym and health club weight lifters take steroids -- a majority non-athletes who are more interested in a muscular appearance than athletic prowess.
"For athletes requiring speed and strength and men desiring a cosmetic muscle makeover, illegal steroids are a powerful lure, despite the risk," Evans writes.
And users of steroids consume them with a vengeance. Doses range from 300 milligrams to more than 3,000 milligrams a week (more than the amount of testosterone that a normal male body produces in a year). Some of the drugs are injected, others are taken orally, but all may produce more than just muscle.
Androgen receptors, after all, are not confined to muscle tissue -- you can find them in the brain and in other parts of the body. So side effects are inevitable.
Steroids may raise blood pressure, reduce good cholesterol levels and cause other heart problems. Brain-related effects can include mood swings, depression and occasional outbursts of rage.
Scientists still debate the seriousness of such side effects. Good experiments are hard to find -- it isn't exactly ethical to give people huge doses of illicit drugs to see just how bad they can be. Studies on rats and mice, however, show that steroids' effects can be wide-ranging, especially in the brain.
For example, mega-doses of steroids clearly influence the activity of the brain molecule serotonin, involved in mood and aggression, Dartmouth College steroid researchers Ann Clark and Leslie Henderson reported last year in Neuroscience and Biobehavioral Reviews.
And the evidence indicates that steroid use alters the activity of "a broad range of other signaling molecules in the brain."
Doses similar to those taken by human abusers "elicit significant changes in aggression, anxiety, and sexual behaviors" in rodents, the researchers wrote.
Sometimes, though, the nature of the effect depends on which type of steroid is taken. And steroids' effects on physical activity, thought processes, and learning and memory seem inconsistent, so more research is needed in those areas. Steroids' potential for addiction remains unclear as well.
In general, the research suggests that short-term effects of steroid use are not necessarily severe or permanent, but troubling questions remain, especially about prolonged use. That issue has become especially significant in light of the growing number of teens (both male and female) who have succumbed to steroid temptation.
"Recent reports highlight the fact that the more insidious growth in abuse of these drugs is not among elite athletes, but among adolescent boys and girls," Clark and Henderson noted. (Perhaps 4 percent of high school students have used steroids, various studies estimate.)
Starting young, of course, allows steroid use for a potentially very long time, with hazards that researchers today cannot clearly identify.
"The health risks associated with long-term ... doses of anabolic-androgenic steroids," writes Evans, "are unknown."
But it's a pretty good bet that if you're a steroid abuser, getting kicked out of baseball won't be the worst thing that happens to you.
Tom Siegfried is science editor for The Dallas Morning News