Want to be top dog in the gym? Then you'll need to learn the world's hardest gym moves: the gym ball dumb-bell squat and the gym ball single-legged press-up with jackknife rotation. But be warned, there's a reason why performing them will have all other gym dwellers looking at you with a mixture of awe and fear - they are staggeringly difficult. We're not calling them the world's hardest gym moves for nothing!

‘They’re definitely a challenge,’ says top trainer Gideon Remfry, who created them. ‘They’re not necessarily that useful either, but they’re good for catching the ladies’ eyes.’

If you want to avoid doing yourself an injury and looking stupid, the key is to build up slowly. With the gym ball dumb-bell squat, start by learning how to kneel on a gym ball. Once you can do that, progress to standing before moving on to squatting and finally adding weight.

Try the world's hardest gym moves now.