VideoScientists unravel mysterious Law of Loose Laces, proving that the way we tie our shoes is rubbish

Things can start to unravel at any moment, but when failure occurs it is swift and catastrophic. This is the conclusion of a scientific investigation into what might be described as the Law of Loose Shoelaces.

The study focused on the mysterious phenomenon by which a shoe is neatly and securely tied one moment, and the next a flapping lace is threatening to trip you up – possibly as you are running for the bus or striding with professional purpose across your open-plan office.

In a series of experiments involving a human runner on a treadmill and a mechanical leg designed to swing and stomp, the scientists revealed that shoelace knot failure happens in a matter of seconds, triggered by a complex interaction of forces.

Oliver O’Reilly, a professor of mechanical engineering at the University of California Berkeley and the study’s senior author, said: “It’s unpredictable but when it happens, it’s in two or three strides and it’s catastrophic. There’s no way of coming back from it.”

The study found that the stomping of the foot gradually loosens the knot while the whipping forces produced by the swing of the foot act like hands tugging on the ends of the laces. As the tension in the knot eases and the free ends start to slide, a runaway effect takes hold and the knot suddenly unravels.