Major League Baseball has its problems. Attendance has slipped, fans complain the pace of play has slowed, players are convinced the baseballs are juiced and even the people running it admit its fusty rules could use an upgrade.
Yet its players might take comfort in one promising bit of news: they appear to have longer life spans than other Americans.
That’s the tantalizing possibility raised by a study published by Harvard researchers in the medical journal JAMA Internal Medicine.
ftooThe sample size used to draw its conclusions is not large — a review of 10,451 major leaguers who died between 1979 and 2013 — and the differences in longevity with the general population are not great. But the scientists determined that, based on their sample, major leaguers live 24 percent longer than the average male. They have also found some limited evidence that players at some positions — notably middle infielders — might live longer than others.
Not all players find these assertions convincing. Didi Gregorius of the Yankees seemed skeptical that shortstops like him lived any longer than anyone else. “I don’t do anything special about exercise or diet,” he said. “I just hang out.”
Austin Romine, the Yankees catcher, said he thought better fitness — the baseball season is seven months long — could be the explanation. “We’re exercising our entire bodies, every day, for 160 games,” he said. “It’s the longest season in sports.”
The study offered a number of possible explanations, including what the players see, that they are generally fitter than average people.
Another study, published in 2006, found that while major league players lived an average of 4.1 years longer than the general public, those with careers lasting 11 years or more lived 7.4 years longer. This suggests a simple answer: Healthier baseball players have longer careers, and healthier people live longer.
Yet the new study found subtle differences between major leaguers and the rest of the population in causes of death.
For example, while a long career was associated with a decrease in the mortality rate for cardiovascular disease, those same longtime players had higher rates of death from cancer, particularly of the lungs and skin.
“We could suspect sun exposure or tobacco for those cancers,” said the senior author of the study, Marc G. Weisskopf, a professor of epidemiology at the Harvard T.H. Chan School of Public Health, “but they also had higher rates of blood cancer, which is surprising.” The authors could only speculate on reasons — including the possibility of exposure to chemicals used to treat fields — because they did not study possible causes.
Some major league stadiums ban the use of tobacco during games by players and fans, and tobacco use in the minor leagues has been banned since 1993. Smokeless tobacco is prohibited for any player entering the league after 2016. All teams participate in a joint effort of M.L.B., the Major League Baseball Players Association and the American Academy of Dermatology to raise awareness about the dangers of sun exposure and provide information about skin cancer prevention and screening.
The researchers found that major leaguers, unlike professional football players, had no increased rates of dementia, Alzheimer’s, amyotrophic lateral sclerosis (known as Lou Gehrig’s disease) or Parkinson’s. This contrasts sharply with National Football League players. A recent study found that compared with M.L.B. players, football players had almost three times the mortality from these neurological diseases.
Compared with pitchers, shortstops and second basemen had lower rates of death from disease. Outfielders were less likely to die of injuries, but the difference there, while real, was not dramatic.
When Romine heard that outfielders are less likely than other players to die of injury, he responded with what could be interpreted as a certain degree of catcher’s contempt.
“Yeah,” he said. “They’re too far away from the ball to get hurt.”
Dr. Weisskopf had a more sober assessment.
“Not that there’s a tremendous physical difference between infielders and other players, but they do tend to be smaller, more slender and lithe,” he said. “That could be a health factor.”
The researchers found that catchers had higher rates of mortality from diseases related to the groin area and urinary tract than other players. “That one catches my eye,” Dr. Weisskopf said, “because it was highly elevated.” But the obvious explanation — that catchers crouch a lot and get hit in the groin — may not be the correct one, and the reason remains unknown.
Over all, there may be another factor contributing to the long lives of players: Major League Baseball has a robust retirement program, regarded as among the most generous in professional sports. Players get substantial pensions even after spending just a few months in the big leagues, and all players qualify for full medical benefits beginning on the first day they join a team.