Target: triceps

Why it works: By exercising unilaterally (one arm at a time), you allow each muscle group to work at full effectiveness and promote muscle balance in your arms. The diagonal pull hits the triceps from a different angle to maximise muscle fatigue.

• Stand side-on to a cable machine set on a high pulley to your left, with feet shoulder-width apart.
• Brace your core and then draw the handle across your body and straighten your arm.
• Pause for peak contraction and then let the cable back slowly.