When it comes to high-intensity moves, it's fair to say I have a love-hate relationship with them. I love the sweaty, endorphin-fuelled high that follows them, but actually doing the exercise? Not so ...

But no one wants to spend more time revving that heart rate than they have to, so you want to make sure you’re opting for the move that will hit you hardest. Mountain climbers may be classic, but it’s ...