July 19th, 2011
07:51 AM ET

Scientist: Tae Bo workout sent skyscraper shaking

Seventeen people performing a vigorous Tae Bo workout caused tremors that forced the evacuation of a South Korean skyscraper earlier this month, the building's owners say.

Prime Group, owner of the 39-story TechnoMart commercial-residential high-rise in Seoul, said 17 middle-aged people were working out to the pop song "The Power" by Snap on July 5 when their movements set the upper floors of the tower shaking for 10 minutes, according to a report from the Korea JoongAng Daily.

Scientists recreated the event in the 12th floor gym, according to a report in the Korea Times.

“We observed the vibrometer while performing the same kind of aerobic exercise that was performed at the time of the shaking which occurred on July 5. We noticed that the shaking was felt in the upper floors while the exercise was being performed while no other place showed signs of tremor,” Chung Lan, a professor of architectural engineering at Dankook University, told the Korea Times.

“It just happens to be that the vibration cycle caused by Tae Bo collided with the vertical vibration cycle unique to the building,” Chung told the Korea Times. The action amplified the building's vibration and caused the shaking, he said.

Chung was one of six professors from the Architectural Institute of Korea who inspected the building and recreated the Tae Bo exercise.

Tae Bo is a mixture of boxing and tae kwon do.

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Filed under: South Korea • World
soundoff (322 Responses)
  1. Ronald Hussein Reagan

    "Bam to the jam boogie woogie jam slam everybody sweat now." Isn't that the one?

    July 19, 2011 at 12:43 pm | Report abuse |
    • Laura

      No. It is ive got the power

      July 19, 2011 at 12:50 pm | Report abuse |
    • Ronald Hussein Reagan

      You're right I got it mixed up with Freedom Williams and C and C Music Factory.

      July 19, 2011 at 1:00 pm | Report abuse |
  2. sk

    This is what happened to the tacoma narrows bridge in 1940. Wind caused the supension wires to vibrate in at the same frequency as the bridge's natural frequency (i.e. resonance). It was caught on film – google it.

    July 19, 2011 at 12:43 pm | Report abuse |
    • David C

      But weren't they doing their Tae Bo workd out to Glenn Miller on that one?

      July 19, 2011 at 1:26 pm | Report abuse |
    • Matthew

      I'm glad you posted first. All I could think of was the Verrazano-Narrows Bridge. 8^)

      July 19, 2011 at 1:26 pm | Report abuse |
  3. Robert in San Diego

    During WW11 the American service men had to break step when marching across the Clifton Suspension bridge in Bristol UK because they created alrming resonence and the powers that be were scared they would cause the bridge to collapse,

    July 19, 2011 at 12:45 pm | Report abuse |
    • SDJ

      World War Eleven? Holy Sh1t! I must have missed a few...

      July 19, 2011 at 12:56 pm | Report abuse |
    • Benny

      LOL @ SDJ

      July 19, 2011 at 1:40 pm | Report abuse |
  4. Anthony

    I bet some terrorist hiding in a cave in pakistan is thinking right now that they have to start recruiting new terrorists from aerobics classes at 24 hour fitness. Al Qaeda in spandex is the biggest threat this country will ever face.

    July 19, 2011 at 12:48 pm | Report abuse |
    • BenA


      July 19, 2011 at 12:55 pm | Report abuse |
    • Mitchell

      YESSSSS!!! they will call it dance dance revolution. or perhaps Jihading to the oldies,

      July 19, 2011 at 1:29 pm | Report abuse |
    • David C

      Wait until the Truthers here about this.

      July 19, 2011 at 1:29 pm | Report abuse |
  5. gaucho420

    Now that's a f'ing workout!

    July 19, 2011 at 12:49 pm | Report abuse |
  6. f

    I am a property manager for major high-rise office buildings in NYC. This is the biggest crock of BS I ever heard. There is something serioulsy wrong with the building and they better find it and fix it asap. They should keep the building empty until it is fixed. There is no way 17 people can bounce/shake an entire high rise building by doing execises. Maybe if one thousand people did it on the roof you might feel some movement. And why for 10 minutes? The song is not nearly that long. This is a coverup. Google the Citigroup Center building for a similar coverup and repair. The building was ready to collapse years ago and it was fixed/welded in the dark of night, one small piece at a time.

    July 19, 2011 at 12:54 pm | Report abuse |
    • Johnny T.


      July 19, 2011 at 1:01 pm | Report abuse |
    • BS

      Hmm, my first reply didn't show up....

      You may be a property manager, but you're not a physicist, architect, etc. Please look up the term resonance and see some examples of the amazing destruction that can be caused by it.

      July 19, 2011 at 1:04 pm | Report abuse |
    • Rob

      Theoretically, a single cat could cause the collapse of a suspension bridge if it walked at the right pace. Google resonant frequency and stick to collecting rent checks and fixing restrooms.

      July 19, 2011 at 1:08 pm | Report abuse |
    • r

      I never knew that!

      July 19, 2011 at 1:10 pm | Report abuse |
    • mattqu

      Johnny T beat me to it. Yup. You might be a manager, but scientist you are not. Resonance is very common in nature.

      July 19, 2011 at 1:13 pm | Report abuse |
    • Todd G

      Somebody doesn't know anything about physics...

      Resonance is one of the most powerful and violent forces in the universe.

      July 19, 2011 at 1:20 pm | Report abuse |
    • j

      Mechanical resonance was debunked on Mythbusters, at least to this scale.

      Yes, the concept exists, but you'd need a LOT more than 10 people to shake a high rise. And they'd all have to be in perfect sync and not change their pace at all. One person misses a step, and it breaks the resonance.

      July 19, 2011 at 1:26 pm | Report abuse |
    • BS

      I believe Mythbusters was trying to knock a building down. Not simply cause vibrations. It's not debunked. They were able to replicate the vibrations.

      July 19, 2011 at 1:29 pm | Report abuse |
    • j

      BTW, if you read the Wikipedia entry on Mechanical Resonance you'll see a very telling line, right at the top:

      It may cause violent swaying motions and even catastrophic failure in improperly constructed structures including bridges

      Key part: Improperly constructed.

      Any building, especially a high rise, will be built to withstand the force generated by 20 people, easily. It should easily withstand the force generated by 200 people, unless it's poorly constructed.

      July 19, 2011 at 1:32 pm | Report abuse |
    • Dev

      Are you a Structual Engineer?

      July 19, 2011 at 1:39 pm | Report abuse |
    • j

      @BS: The guys on MB made a good sized piston with variable speed, and attached it to a bridge (after much small scale testing) They were able to dial in the speed of the piston to exactly match the resonant frequency of the bridge they were on, which is much more precise than a group of Tae Bo'ers can aspire to, but couldn't get any detectable effect more than a few feet away from the piston itself.

      Any anecdotal stories you hear about military or marching bands causing bridges to shake is one of two things: a fabrication/embellishment or simply too many people trying to cross a poorly constructed span.

      As for the building in the story, I'm voting "poorly constructed." Just a hunch.

      July 19, 2011 at 1:42 pm | Report abuse |
    • BK

      j... it did not cause mechanical failure or cause the building to sway... just vibrate. that is normal with mechanical resonance. Stop thinking there is a conspiracy, and let physics do the explaining.

      July 19, 2011 at 1:46 pm | Report abuse |
    • BK

      also... the type of material used both effects the frequency required and the speed/distance vibrations could be carried. steel carries sound and vibrations at high speeds and long distances, compared to stone. That is why a stone/ concrete bridge may not have been affected as much.

      July 19, 2011 at 1:48 pm | Report abuse |
    • j

      @Dev: Computer systems hardware engineer. I deal with shock vibration and the effects it has on computer racks all the time. I.E. How many Gs of shock can a 10k RPM hard drive in a Sun SPARK system withstand (both while in operation and while powered off) mostly pertaining to installing server systems on naval vessels.

      I was also in a high school marching band, back in the day, and served in the Marines. Anyone who claims their band or platoon could keep everyone in perfect lockstep long enough for resonance to build is full of it. Every group, I don't care how big, will have at least one rock who couldn't keep a steady pace, even with a metronome shoved up his as-.. ear! And that one person going against the grain (even if their foot hit a fraction of a second after yours) is enough to dampen the resonance.

      July 19, 2011 at 1:49 pm | Report abuse |
    • BS

      I don't remember the show that well. But Mythbusters doesn't always get things right. They're pretty good, but they're still entertainment and not true science.

      July 19, 2011 at 2:10 pm | Report abuse |
    • iamthefredman

      As a PM I know all about the resonance that you are all referring to. It does not occur in a 12 story building caused by 17 people unless there is something seriously wrong with the structural design. The taller the building the more resonance is possible. This building is only 12 stories. I worked in Citigroup Center in NYC. There is a 400-ton harmonic tuned mass damper in the top of the building to counteract wind shear and resonance. Basically, a giant free-moving pendulum.

      July 19, 2011 at 3:02 pm | Report abuse |
    • BS

      The building is 39 stories, not 12 stories. And it's not Citigroup center, so it doesn't matter what is in that building.

      July 19, 2011 at 4:46 pm | Report abuse |
  7. f

    Google "citigroup center repairs". Shocking. The bank let their employees keep working while repairs were being done and without telling the employees or NYC authorities about the problem.

    July 19, 2011 at 12:57 pm | Report abuse |
  8. Adam

    I don't know if it's true but I read somewhere if everyone in China jumped off a 6 foot platform at the same time they would create a seismic wave that would be devastating to anyone on the other side of the globe.

    July 19, 2011 at 12:57 pm | Report abuse |
    • deuce

      Uh, that's crap. The mass of the Earth is billions of times heavier then even the total weight of all the people on Earth combined, so you'd need either a considerably heavier object or a considerably faster one to have any effect like that on the earth.

      Just a fallacy.

      July 19, 2011 at 1:11 pm | Report abuse |
    • iamthefredman

      If true, that would be sooo cooooool !!!!! Hey dudes, let's try it. (This is the basis for all 'America's Funniest Home Videos' and You Tube)

      July 19, 2011 at 3:36 pm | Report abuse |
  9. Benny

    So by the facts in this article 17 people (lets average them at 180 lbs totaling 3060 lbs) doing Tae Bo caused a 39 story high rise to "BOUNCE UP AND DOWN" as stated in the original article by an eye witness.

    Ughhh.... Yea.... I AM NOT A CONSPIRACY NUT but cover-up or stupidity, you be the judge.

    "...vertical vibration cycle unique to the building..." Again... Ughhh.... Yea....

    Seems as if they came up with this answer a little too quickly and used Telsa's principles too loosely to form an acceptable answer.

    How long before the building collapses due to the actual reason for the "Bouncing"? How many people will die for this?

    July 19, 2011 at 1:00 pm | Report abuse |
    • BS

      It seems more likely that you do not understand physics. Small, repetetie forces acting at the same frequency as an object's natural resonance frequency can, over time, build up to very large movements. This is how sound of a certain frequency can break glass. Or how a suspension bridge can wind up twisting wildly in the wind and collapsing. Just because you don't understand it doesn't mean it's not real.

      July 19, 2011 at 1:03 pm | Report abuse |
    • Benny

      @BS ... "over time"... I absolutely agree with you. As you falsly assume, you are not the only one with a rudimentary knowledge of physics. I am not saying that such an occurance isn't possible. I am simply saying that a 30 minute video of Tae Bo probably isn't considered "over time"...

      Just because you understand something doesn't mean it can't be something else. Smarty Pants!

      July 19, 2011 at 1:07 pm | Report abuse |
    • Rob

      By "over time," I believe BS meant minutes. Theoretically, a single cat could cause the collapse of a suspension bridge if it walked at the right pace.

      Some light reading for you: http://en.wikipedia.org/wiki/Resonance
      And if you're not a fan of reading: http://www.youtube.com/watch?v=dm0XXuFt30k

      July 19, 2011 at 1:14 pm | Report abuse |
    • BS

      They brought in experts and replicated the issue. It doesn't matter what you think, they already proved it. Or this is a giant conspiracy involving building management, a bunch of scientists, an exercise class, and the media. The former seems more plausible than the latter.
      You can't just arbitrarily say it's not enough time. "Over time" is relative. It could be seconds, hours, days, months, years, etc depending on the conditions.

      July 19, 2011 at 1:18 pm | Report abuse |
    • mattqu

      Telsa who? First, you mean Tesla. Second, he has nothing to do with this (is he really the only scientist people respect nowadays?). You mean Newton. He's the go to guy for simple mechanical systems. Basic resonance frequency. It's not a cover up, they were able to recreate the vibration. It is probably just a minor design flaw in the building, not enough to bring the building down, but enough to cause it to shake a little. When people dance, they do it to a rhythm and a beat. This happened to be the harmonic frequency for the building. Conspiracy solved.

      July 19, 2011 at 1:25 pm | Report abuse |
    • Benny

      A very large part of me wants to stick my fingers in my ears and mumble about not hearing you... A smaller part of me agrees totally with you... Especially when I searched the credentials of Dankook University...

      I've just got a nagging feeling. Maybe I am a conspiracy nut.

      It just seems too convienient and timely an answer.

      "Only two things are infinite, the universe and human
      stupidity, and I'm not sure about the former." – Albert Einstein

      July 19, 2011 at 1:26 pm | Report abuse |
    • Gaffe

      @ Benny... Tesla?? You weren't kidding when you said "rudimentary knowledge of physics".

      July 19, 2011 at 1:27 pm | Report abuse |
    • Benny

      @Gaffe – LOL OK! Kill me for a typing error. Telsa – Tesla Come on people! I must have mispelled something else!

      Where is the guy who wrote 50 page responces on the last article to back me up here?

      July 19, 2011 at 1:34 pm | Report abuse |
    • J

      Actually, yes, it was Tesla.

      Sorry to burst all of your foaming-at-the-mouths-to-point-out-errors bubbles. Read up before you try to mock.

      I'll give you a small snippet:

      July 19, 2011 at 1:36 pm | Report abuse |
    • f

      You get what you pay for....."Made in Korea"

      August 2, 2011 at 3:06 pm | Report abuse |
  10. TempTag

    The same thing happened at the building I work in where an exercise class caused vibrations. They moved the class to the first floor and it was not a problem.

    July 19, 2011 at 1:01 pm | Report abuse |
    • BS

      I don't know.... Based on some of the comments being made here, you must be a liar. (just kidding!) Resonance is an amazing phenomenon.

      July 19, 2011 at 1:06 pm | Report abuse |

    So this what you call a shaking towering experience.

    July 19, 2011 at 1:10 pm | Report abuse |
    • I h8 NYC

      BOOOOO! That was horrible.

      July 19, 2011 at 1:53 pm | Report abuse |
  12. USArmyOverLord

    That must be one hell of a workout. SIGN ME UP!!!

    July 19, 2011 at 1:15 pm | Report abuse |
  13. Tim

    How fat were these 17 people?

    July 19, 2011 at 1:24 pm | Report abuse |
  14. D

    This just in from the Nature section: "The sun is expected to set today leaving billions without light"....

    July 19, 2011 at 1:24 pm | Report abuse |
  15. J

    Back in high school when our marching band would cross bridges, we could feel the bridge bounce under our feet. More than once, they made us break unison marching steps to avoid this.

    July 19, 2011 at 1:32 pm | Report abuse |
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