Rumor Doctor blog archive
Can running the Marine Corps Marathon make you shorter?
Published: October 17, 2011
Running is definitely not The Rumor Doctor's favorite pastime. In fact, The Doctor believes that running became obsolete with the invention of the internal combustion engine.
But since some readers may be participating in the upcoming Marine Corps Marathon this month in Washington, D.C., The Doctor felt it was a good time to investigate a running rumor: Marathon runners are measurably shorter at the end of the race than at the beginning.
The theory is that long-distance runners can actually shrink during the course of the race because pounding the pavement compresses the discs between the vertebrae in your back.
The easiest way to test this theory would be to have The Rumor Doctor run a marathon and measure him afterward to see if he shrank, but The Doctor hasn't been in shape to run long distances since the first President Bush was in office. Another method needed to be found.
Therefore, The Doctor turned to Jeremy Soles, a former Marine who set a Guinness World Record last year by running the Marine Corps Marathon in a gas mask to honor a wounded warrior.
Soles, who has run a total of four marathons, 15 half marathons, and close to 50 other races, said has never heard of runners getting shorter, nor has he gotten shorter himself, at least as far as he knows.
"That being said, just because I have never heard of it, does not make it untrue," Soles said in an email.
That, as it turns out, was a wise caveat.
Recent studies have shown that running can in fact make you shorter, but not by much and not for long, according to Navy Capt. Daniel Unger, a top orthopedic and sports medicine specialist based out of Naval Medical Center Portsmouth, Va.
The discs between the vertebrae in your back are roughly 80 percent fluid, so dehydration combined with the constant compression on the discs caused by running can cause them to shrink, he explained.
"There can be anywhere from a couple millimeters to up to 2 centimeters in various individuals in shortening after running for an hour," he said.
However, the discs go back to normal once the pressure on them is relieved and runners have a chance to rehydrate, Unger said. To his knowledge, there is no danger that the shortening could become permanent.
THE RUMOR DOCTOR'S DIAGNOSIS: Running the Marine Corps Marathon can make you a wee bit shorter temporarily, but it’s nothing a little post-race drinking can’t fix. Sorry, not alcohol. Semper Fi.