We wouldn’t go so far as to call it one of life’s great mysteries, but on just about every running shoe you’ve ever bought you’ve probably noticed the extra shoelace hole at the top of the shoe, but never known what it’s for.

The short answer: it’s the end of all your blister-related problems. If you don’t know this, you need to.

As the above video explains, the extra loop is there so you can create a ‘heel hock’ or ‘lace lock’. The idea of the lock is to make sure your shoe fits tight and snug around the ankle, without offering extra pressure on other parts of the foot.

First, feed your lace backward into the top hole to create a small loop – do this on both sides of your shoe.

Next, thread your lace through the loop on the opposite side of the shoe and pull down toward the shoe to create the lock.

Finally, lace your shoes as per usual. Done!

As the video description puts it, “This keeps the ankle and heel area nice and tight, without having to tighten your whole shoe. It also helps to prevent black toenails by keeping your heel and your toes from smashing into the front of your shoe.”

How frustratingly easy is that! Think of all the shoes you’ve found to be really comfortable until you start running in them and they don’t quite offer the support and friction you need around the ankle, so you’ve taken them back. All you ever needed to do was tie your laces in a slightly different fashion!

The video was created by Illumiseen, who make an LED sash-style belt designed to make runners more visible at night, but also offer “useful tips as well”.

Their belts are rechargeable, so they claim you’ll “never have to buy new batteries again”, and you can buy them for $US29.99 ($AU38) on Amazon.

Or, y’know, keep nicking hi-vis vests from work and running in those. Cheaper and, if the Newcastle Knights are to be believed, far more fashionable.