It's no secret that Justin Bieber takes pride in his physique - and he's lifted the lid on his gym routine with a new Instagram picture.

The 20-year-old shared a snap of himself supporting his own weight with his arms, while holding his legs out at 90 degrees.

Wearing a baseball cap and attempting to look unflustered by the exertion, Biebs wrote: "What a solid core. Lol #stayfit #dontbescared"

We wonder if he's trying to impress his rumoured new squeeze, model Yovanna Ventura.