MONDAY, July 29, 2013 (HealthDay News) -- College football players, particularly burly linemen, may develop high blood pressure in just one season of play, new research suggests.
The study of 113 freshmen on Harvard's football team found that while none had high blood pressure at season's start, 14 percent did by season's end. All of the affected players were linemen.
Experts said the significance of the blood pressure increase is not clear. The study did not follow the players long enough to see if their numbers fell again during the off-season, for example.
"I think this is provocative, but we need further study to determine the significance," said Dr. R. Todd Hurst, of Mayo Clinic in Scottsdale, Ariz.
In the meantime, young football players should eat a balanced diet and have routine blood pressure checks, added Hurst, who was not involved with the research.
A number of past studies have found that, after retirement, former professional linemen have higher-than-average rates of high blood pressure and clogged heart arteries. But it hasn't been clear whether some young players might be showing early signs of heart trouble ahead.
So for the new study, Dr. Aaron Baggish and colleagues at Massachusetts General Hospital in Boston followed first-year players on Harvard University's football team over six freshman seasons. They also followed members of the men's rowing team, as a comparison group.
Overall, the number of football players with "prehypertension" rose from 39 percent pre-season to 47 percent by season's end. And while no player had full-blown high blood pressure pre-season, 14 percent developed it during the season.
In contrast, the rowers' blood pressure declined, on average, and none developed high blood pressure.
There could be a number of reasons for linemen's blood pressure increase, Baggish said, "but the weight gain is almost certainly a driving factor." Even if some of the weight was muscle mass, that could still affect blood pressure, he noted.
It's also possible that training has something to do with it. Baggish said that lifting heavy weights triggers short-term spikes in blood pressure; but no one is sure if that can lead to chronically high blood pressure over time.
Regardless, the findings suggest that the heightened heart disease risks seen in retired pro linebackers may start to take shape early in their careers, according to Baggish and his colleagues. Their report appears online July 29 in the journal Circulation.
But another cardiologist who was not involved in the research said the study had a number of limitations, and it's hard to draw conclusions.
"The issue is, what is causing the hypertension? And does it regress after the season is over?" asked Dr. Martin Goldman, a professor of medicine at Mount Sinai in New York City.
Goldman's own work has found that retired NFL linemen have higher rates of heart disease risk factors than other former players. But he was cautious in interpreting the current findings; a major reason, he said, is because the researchers did not follow the same players over their college careers.
"Maybe they are hypertensive during the season, and it gets better off-season," Goldman said.
Any number of factors could explain why linemen's blood pressure rose during their first season, both Goldman and Hurst said.
One possibility is weight gain; linemen put on an average of 7 pounds, whereas other football players held a steady weight. But, Goldman noted, those extra pounds could have been muscle.
"Maybe it's the stress of being a first-year student-athlete at Harvard. Maybe it's their diets as college freshmen. Maybe it's all the Gatorade they're drinking on the sidelines," Goldman said, noting that the electrolyte-replacing drink contains a lot of sodium.
Goldman also said that rowers are not an ideal comparison group, because those athletes actively try not to gain weight. Their diets or other habits -- like drinking alcohol -- may be very different from football players'.
It could be more informative, Goldman said, to use a different sport, like baseball, as the comparison -- or to compare football players to non-athlete students.
Hurst agreed that the findings raise more questions than answers. "I think these results are hypothesis-generating rather than definitive," he said.
According to Hurst, the take-away is that young football players are not "immune" to health issues just because they are athletes.
"It is important that they eat a healthy diet and are screened by medical professionals for high blood pressure, high cholesterol and high blood sugar," he said.
Baggish said the bottom line is that linemen should have their blood pressure checked before and after the playing season. That's especially important if they gain weight during the season or if a parent has high blood pressure; both of those factors were linked to blood pressure spikes in the study.
The American Academy of Pediatrics has more on high blood pressure in young athletes.