When you're aiming to hit multiple muscle groups with one exercise, it pays to think about your positioning.
That's how Men's Health fitness director Ebenezer Samuel, C.S.C.S. makes the most of this arm day workout. He takes a single-arm skull crusher—an exercise that typically isolates the triceps—and adds a healthy dose of balance and anti-extension action that makes your core work overtime to keep yourself stable.
"The half-bench skull crushers are cancelling out one of the main things people are sloppy with on skull crushers: If they don't have great shoulder range of motion overhead, they compensate by arching their back," Samuel says. "From that half-bench posture, you can't really arch your back, so your purer shoulder mobility comes out."
To perform the half-bench skull crusher, you'll need a sturdy bench and a light to medium weight dumbbell. Check out this adjustable option from Bowflex if you don't have a set handy.
- Lie back on the bench with a dumbbell in one hand. Shift yourself over to that side so that your spine, half your torso, and one glute are completely off the bench. Squeeze your glute and brace your core to keep a strong, stable base throughout the exercise.
- Lift the dumbbell so that your arm is at a 91-degree angle with your torso. Extend the opposite arm straight out to the side to help keep your balance.
- Hinge your elbow to lower the weight straight down beside your head, then squeeze your triceps to lift it back into that 91-degree position.
Strict form is important to get the most out of the position here, so don't hesitate to drop to a lower weight if you have a hard time controlling the dumbbell's path through the full rep. That adherence to your position will make the anti-extension quality of the movement even more pronounced. "The weight going straight backwards will try to pull your torso upwards and backwards," Samuel says. "You have to flex your abs against that, flattening out on the bench, honing posture, and crushing your abs more than you expect."
To add the half-bench skull crusher to your arm day, try 3 sets of 10 to 12 reps per side.
This article originally appeared on Men's Health
