Shoelaces coming untied is one of life's everyday annoyances. Apparently it bothers scientists too.
Using slow-motion images of people running, researchers were able to identify the forces that pull shoelaces undone. They found that your foot hitting the ground repeatedly stretches then relaxes the knot, while the force of swinging your leg tugs on the ends of the laces.
This might not sound like important research, but scientists say that understanding basic knot structures will help them understand the dynamics of smaller knots - such as strands of DNA.