"In general, people get shorter throughout the course of the day just by being upright due to disc compression," Dr Brian J. Campbell, who led the study, told Reuters Health.
"We've found that the added load of all the equipment on a football player and then the compressive forces these football players have with colliding with each other accelerates the shrinking process."
Campbell and colleagues studied 10 high school football players playing positions that would likely exert repetitive compression of the spine over the course of the game due to blocking, tackling and other football manoeuvres. An athletic trainer measured the height of each player before and after the game.
Almost one centimetre lost during game
The average height of players before the game was 176.56 centimetres. After the game, it was 175.81, the researchers found. "The results indicate that high school football players' heights decrease during the course of a game by almost one full centimetre," Campbell said.
"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," he said.
From an injury standpoint, the spine is less able to absorb impacts when there is spinal compression, Campbell said, and the role of hydration should not be overlooked. "The discs are composed mostly of water and if you took a water balloon and sandwiched it between your hands and took a needle and extracted some of that water, it's going to shrink or compress," Campbell explained.
"We aren't saying people shouldn't play football, but in a game of inches, if you shorten a little bit, that might be the difference between a game winning catch or a blocked field goal," Campbell said.
"It may be a good idea at half-time to unload players' vertebrae by having them lie down and get off their feet and unload the spine in hopes that the spine can reabsorb some of the fluid so that in the second half they wouldn't have so much disc compression," Campbell suggested. – (Reuters Health)
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