Tufts physics professor Roger Tobin explored whether steroid use in Major League Baseball could be the sole factor behind the rapidly rising single-season home run record. While other records are apparently unperturbed by steroid usage, Tobin concluded that the single-season home run record was particularly sensitive to increases in strength, and that steroid usage alone could account for its recent rise. The lecture was held last Friday, January 22 at the Thayer School of Engineering’s weekly Jones Seminar.

In 1927, Babe Ruth hit 60 home runs in a single season, a record that was only broken once in the next seven decades. Even when Roger Marris broke the record in 1961, he was only able to increase it by one home run, to 61. For 71 years, these two men remained the only players who had hit 60 or more runs in a single season.

But in the past ten years, the record has been barraged by sluggers, breaking Marris’s record six times since 1998. Sammy Sosa, Mark McGwire, and Barry Bonds, all suspected of steroid usage, have hit more than 60 home runs in a season. “Is it possible that steroids could produce this sort of effect?” Tobin questioned. “If so, there is something special about home runs.”

Indeed, other sports have seen steady but gradual record-breaking in the recent decades. Even records in other sports with known steroid usage such as sprinting seem to be immune to the effects of steroids. Tobin pointed out that the 100 meter dash time has only decreased 2.6% since 1980, and the 100 meter freestyle swimming record has only decreased 4.5% in the same time.

Tobin used physics to address the question. He first analyzed the anatomical effects of steroids, which produce approximately a ten percent increase in muscle mass. This increase in muscle mass translates to about a three percent increase in the speed of the ball as it leaves the bat.

Tobin’s equations, which considered the force of gravity, air resistance, and spin, indicated that even a three percent increase in ball speed could produce the observed 20 to 30 percent increase in home runs. This is because elite sluggers tend to hit a large number of balls just shy of the home run wall. If the distribution curve for balls hit were increased even by a small amount, many near home runs would become real home runs.

Tobin stressed that steroids could only have such a marked effect in the best hitters, since only these players hit the necessary number of “near home runs.” Additionally, home runs are special particularly because some players hit so many near home runs. Other statistics do not respond so drastically to a three percent increase in power.

Tobin’s research on the subject was published in the American Journal of Physics. (Tobin, R. G. Am. J. Phys. 76, 15-20 (2008).