We haven’t normally got much time for the teachings of Jim Bro. As he discovers a way to make the leg press into a biceps workout, we’d rather focus on functional moves, to build muscle that doesn’t just look good in a vest. Until, that is, vest season arrives. Then suddenly we see the benefit of skipping legs day – just this once.

But curls aren’t the only way to build big arms. The quickest route to a torso you won’t want to cover up lies in the oft-ignored muscles around Jim Bro’s faves. Take those curls – they hit your biceps brachii, the muscle that flexes when you point the way to the beach. But your arm is mostly triceps – the muscle on the other side. Target your tris and you’ll discover 60 per cent more muscle to fill your sleeves.

Ditto for your chest. Yes, you bench – probably too much. Which means two islands of muscle that look suspiciously moob-like when they’re covered up. Hit the muscles around your pecs instead and you fill in the gaps, to give more size all over, and a shape that can only mean strength.

The good news is that ignored muscles grow fast the second they’re in the spotlight. Your body responds to change, so it’s hard to squeeze more from areas you’ve worked for a long time, without radically overhauling your diet or logging twice as long in the gym. But hammer a muscle that’s never been stressed before and it responds quickly, forced to grow because it’s overloaded the second you put weight on it.

Even if the vest weather doesn’t last, the body beneath will. And it will still look good beneath a snug crew neck when winter comes.

The Workout

The workout is split into two days, the first aimed at your back, traps and biceps, the second your chest, shoulder and triceps.

Go as heavy as you can without sacrificing form – the more weight you move, the more results you’ll see. Perform each workout once a week, with a legs workout between them. Well, there’s only so far we’ll let Jim Bro steer your training.