Aerobics workout class with a seismic effect

An aerobics class workout causes building to shake in South Korea. No, they weren't dancing to "I feel the earth move under my feet." And other news you can lose.

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The mystery of why a 39-storey skyscraper in South Korea began to shake uncontrollably has been traced to an exercise class.

Authorities evacuated the Technomart building in Seoul after its upper floors began to rock up and down for 10 minutes this month.

After ruling out an earthquake, an investigation has blamed a Tae Bo exercise class being held at a fitness centre on the 12th floor.

They conclude that the exertions of the 17-strong class created a vibration that matched the building's own resonance frequency.

According to Chung Lan, a professor in the architectural engineering department of Dankook University: "When an external vibration hits the resonance frequency of a certain object, the vibration is amplified and causes excess shaking even from slight movement."

Reports suggested that the class was exercising to The Power by the German electronic group Snap! and that a new instructor was pushing them twice as hard as normal.

Not the News of the World

Taliban fighters have complained that their mobile phones have been hacked into.

They say false text messages sent from their phones claiming that the Taliban leader, Mullah Mohammed Omar, had died of heart failure were the result of hacking by "Americans and foreigners".

The movement regularly sends text messages to local journalists to publicise important statements. A spokesman for the Nato military alliance refused to comment on the allegations.

At least he called

Minutes after calling his estranged mother to tell her he was about to "drop in", a Swiss man ploughed his aircraft into her house.

Konrad Schmidt, 47, was piloting his twin-engine light aircraft above the house of his mother in Switzerland when he placed the call.

Schmidt, who had been suffering from depression and was involved in a long-running feud with his mother, made a series of low-level passes of the house before aiming the plane at a bedroom window.

The resulting fireball destroyed the house, killing him instantly. Mrs Schmidt, 69, however, was down in the basement at the moment of impact and survived with minor injuries.

Fight tip: drop the armour

After an experiment that involved a suit of armour and a treadmill, researchers have concluded that medieval battles may have been lost because the defeated knights were exhausted even before wielding a sword.

The weight of the armour would have caused breathing problems, intense fatigue on the legs and drained energy, the survey concludes.

Volunteers were dressed in a reproduction of a 15th-century suit of armour and then asked to walk and run on a treadmill.

The study found that the constricting nature of the metal plates, as well as the weight, would have severely affected their ability to fight, speculating that this could have had a deciding effect on some battles, including the defeat of the French by the English king, Henry V, at Agincourt.

Thom Richardson, the keeper of armours at the Royal Armouries in Leeds, England, said: " It confirms what we have always suspected - heavy armour would very much reduce your ability to run around."