Physicist shows how steroids can fuel home runs

WASHINGTON (Reuters) - Steroids can help batters hit 50 percent more home runs by boosting their muscle mass by just 10 percent, a U.S. physicist said on Thursday.

A view of the outfield at Yankee Stadium in a 2007 photo. Steroids can help batters hit 50 percent more home runs by boosting their muscle mass by just 10 percent, a U.S. physicist said on Thursday. REUTERS/Shannon Stapleton

Calculations show that, by putting on 10 percent more muscle mass, a batter can swing about 5 percent faster, increasing the ball’s speed by 4 percent as it leaves the bat.

Depending on the ball’s trajectory, this added speed could take it into home run territory 50 percent more often, said Roger Tobin of Tufts University in Boston.

“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,” said Tobin, whose study will be published in an upcoming issue of the American Journal of Physics.

Tobin, who normally studies condensed matter and physics, wondered if professional baseball players who have recently been accused of boosting their performance with steroids really would benefit from using the drugs.

“If you look at other sports, you don’t see radical changes in performance. No one is running a 6-second 100-meter dash, no matter what they are taking,” Tobin said in a telephone interview.


Tobin read reports about steroids that said they could add about 10 percent to an athlete’s total muscle mass. Could this be enough to help San Francisco Giants player Barry Bonds, dogged by allegations of past steroid use, hit his record-breaking 756th career home run last month?

“I haven’t tried to look at Barry Bonds specifically so I haven’t looked at his weight numbers,” Tobin said.

What he did look at was the power of a batter’s swing, and how it might affect a baseball.

An extra 10 pounds (4.5 kg) of muscle, he said, could add just enough extra to a batter’s swing to send the ball out of the park, or at least into the stands.

It works for pitchers, too, but not as well.

He calculated that a 10 percent increase in muscle mass should increase the speed of a thrown ball by about 5 percent, or 4 to 5 mph (6.4 to 8 kph) for a pitcher who throws a 90-mph (144-kph) fastball.

That could translate into one fewer earned run every other game.

“That is enough to have a meaningful effect on the success of a pitcher, but it is not nearly as dramatic as the effects on home run production,” Tobin said.

“The unusual sensitivity of home run production to bat speed results in much more dramatic effects, and focuses attention disproportionately on the hitters.”

Tobin said it is possible that baseball players could gain the muscle mass by lifting weights.

“This doesn’t prove anything. This is not an indictment of Barry Bonds or anybody else,” he said.