David Beckham has shared a look at how he trains his abs with an Instagram video which shows him working through a set of hanging knee raises, under strict instruction from trainer Bobby Rich.

The exercise’s name doubles as a form guide: hang from a pull-up bar, then use your core muscles to raise both knees so your thighs pass beyond parallel with the floor.

In the video, Rich can be heard giving the technique cue “knees up to your chest”, although Becks’ caption suggests he had more pressing matters on his mind—namely, the state of his headline-grabbing ’do. If I had hair that nice that would be my primary concern, too.

Benefits Of Hanging Abs Exercises

Performing abs exercises on a pull-up bar is great for breaking away from the monotony core training can entail—planks, crunch variations, you know the drill. Your mid-body muscles are in for a real test too.

“You’re definitely focused on your rectus abdominis because you’re going into a flexion, but instead of flexion from the top like with a crunch you’re flexing from the bottom,” says Wendy Batts, regional master trainer for the National Academy of Sports Medicine.

However, she warns this move isn’t for beginners. Not only do you have to be able to control your body through spinal flexion, but it also requires you to hold your bodyweight. And that’s not all.

To hit the intended range of motion, you need to be able to hang with a neutral spine. If your lower back arches (an anterior pelvic tilt), you have to move your spine to neutral before moving to flexion, and that extra movement is called compensation.

“If you can do it without compensation then I tell people it’s a great exercise,” she explains.

“But you really need to make sure you have good lat extensibility, because if you don’t and you’re hanging you’re going to be in an anterior tilt.

“The lower back will arch, and during this exercise you’re trying to have it do the opposite. This means you’re really not going to get full activation [of the muscles] because you have to go through a compensation first.”

If you struggle with this exercise, try starting with a knee-up, or a reverse crunch to knee-up as demonstrated below (rotation optional).

However, if you have the strength and stability needed to do this exercise properly, Batts says it can be a great tool for developing core strength.

“There are a lot of different variations to make it harder; sometimes one knee up at a time so you have to hang longer, or there are different rotational movements while doing it.

“I have our athletes do it where they’ll raise their knees, kick their legs out, hold this position, and then come down.

“There are a lot of variations to this one exercise that you can progress someone to. You just want to make sure they’re doing it correctly first, then you can have a ton of fun with it.”