FRIDAY, May 30 (HealthDay News) -- Repetitive blocking and the weight of helmets and pads may compress the spine enough to result in a temporary loss of height for some football players, a new study finds.

Previous research has suggested that gravity-related compression of the spine can cause a person to lose as much as 1 percent of their height in a normal day. Fortunately, this height loss is recovered during sleep.

In this study, researchers looked at 10 football players whose positions were most likely to expose them to repetitive longitudinal loading of the spine over the course of a game due to blocking, tackling and other maneuvers.

Each player's height was measured before and after the game. Their average pre-game height was 176.56 centimeters, and their average post-game height was 175.81 centimeters.

"The results indicate that high school football players' heights decrease during the course of a game by almost one full centimeter," study author Brian J. Campbell said in a prepared statement.

"The decrease is likely due to the intermittent high-impact compressive loading of the spinal column during a football game, as well as the low-impact continuous compressive forces from equipment weight. In a game such as football, one centimeter could mean the difference between a game-winning catch or a blocked field goal," Campbell said.

He noted that hydration may play a role in this height loss through the release of fluid from the vertebrae via osmosis. Future research is required to pinpoint why football players lose height during a game, Campbell said.

The study was presented this week at the annual meeting of the American College of Sports Medicine, in Indianapolis.

More information

The American Academy of Orthopaedic Surgeons has more about football.

-- Robert Preidt

SOURCE: American College of Sports Medicine, news release, May 28, 2008

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