Steriods May Boost Home Runs by 50 Percent

First, I want to say it loud and clear I do not care in principle about athletes safely using steroids (or anything else) to enhance their performance. However, athletes may not use such enhancements when the rules of their sports authorities forbid it–that's cheating just like using a corked bat. Anyway, as everyone knows, Barry Bonds' home run record is tainted* by the suspicion that he used steroids.

But there has been some question about how steroids might increase home run production. Tufts University physicist Roger Tobin finds: 

"A change of only a few percent in the average speed of the batted ball, which can reasonably be expected from steroid use, is enough to increase home run production by at least 50 percent," he says. This disproportionate effect arises because home runs are relatively rare events that occur on the "tail of the range distribution" of batted balls…

Tobin reviewed previous studies of the effect of steroid use and concluded that muscle mass, the force exerted by those muscles and the kinetic energy of the bat could each be increased by about 10 percent through the use of steroids. According to his calculations, the speed of the bat as it strikes the pitched ball will be about 5 percent higher than without the use of steroids and the speed of the ball as it leaves the bat will be about 4 percent higher.

To determine the ultimate impact on home run production, Tobin then analyzed a variety of models for trajectory of the baseball, accounting for gravity, air resistance and lift force due to the ball's spin. While there was considerable variation among the models, "the salient point," he says, "is that a 4 percent increase in ball speed, which can reasonably be expected from steroid use, can increase home run production by anywhere from 50 percent to 100 percent."

These results certainly do not prove that recent performances are tainted, but they suggest that some suspicion is reasonable," he concludes.

Press release reporting this research here.  

*used because that's what some commentators suggest should be done with Bonds' entry in the record books.