It's one of the most popular exercises to tone stomach muscles, but a personal trainer has revealed how fitness fans have been planking wrong.
According to the Daily Mail, Max Lowery, from London, who runs the 2 Meal Day channel, said his technique, called muscle contraction, "completely changed" the way he trains, and delivers better results.
In a new video, the YouTuber reveals the wrong way to plank, which can involve holding the pose for up to seven minutes, and then demonstrates his way - and he claims doing it for 30 seconds is enough to get toned abs.
In the footage, which has been watched more than 38,000 times, Max reveals: "There's one exercise in particular that I see being done incorrectly and inefficiently all the time and that's the plank.
"You often see people holding planks for seven minutes - I personally couldn't think of anything more boring.
"I often hold a plank for 30 seconds. And if you're getting 100 per cent muscle contraction, that's all it needs to be."
Max, who works as a personal trainer to top models and TV stars, goes on to say that muscle contraction works to "activate every single fibre in the body" which will improve the way it looks and make it stronger.
In the video, he then shows how he sees most fitness fans doing the plank: "There's nothing wrong with this in principle so long as the back isn't sagging, but I'm not really feeling it anywhere - not in my abdominal region where I want to feel it."
And then Max, who boasts more than 43,000 Instagram followers, demonstrates the "right" way.
"I'm now going to contract my abs as hard as I can right now. It's a lot harder.
"By driving my elbows down, tilting my hips, and tensing my abs as hard as I can... getting 100 per cent contraction on those abs."
Writing on YouTube, fan Venetia Falconer wrote: "Mind blown."
However, not everyone was convinced: Lynda Lippin wrote: "While you may certainly 'feel' your abs in the same way you would in a crunch, you are NOT strengthening any of the back extensors."