The plank is an isometric exercise that targets the core muscles. It involves holding a position similar to a push-up, but instead of lowering yourself down, you hold your body in a straight line for as long as possible. The current Guinness World Record for the longest time holding a plank is 9 hours, 30 minutes and 1 second, achieved by George Hood of the United States on February 15, 2020. However, it's important to note that attempting to break a world record can be dangerous and should only be attempted under the supervision of trained professionals. It's always best to prioritize safety over breaking a record.