Arms
Alternating Iso Hold Skull Crusher
A lying triceps extension where one arm holds halfway down while the other does full reps, then you swap. The hold keeps your triceps working the whole set, so light dumbbells are plenty.
- Works
- Triceps, forearms
- Equipment
- A pair of dumbbells and a bench, box or the floor
- Load
- Light to medium
How to do it
- 1Lie back on a bench, box or the floor. Hold the dumbbells straight up over your shoulders, palms facing each other.
- 2Bend one elbow until the dumbbell is halfway down, elbow at about 90 degrees, and hold it there.
- 3With the other arm, bend at the elbow to lower the dumbbell beside your head, then straighten your arm back up.
- 4Halfway through the set, swap: the working arm holds and the holding arm does the reps.
Cues
- Upper arms stay still. Only your elbows bend.
- Lower beside your head, not onto your face.
- Holding arm stays bent at 90 degrees, no resting at the top.
Common mistakes
- Elbows flaring out. Keep them pointing up and about shoulder width apart so your triceps do the work.
- Resting the holding arm straight. A straight arm takes the work off your triceps. Keep that elbow bent at 90 degrees.
- Going too heavy. The dumbbell passes your head, so control matters more than load. Pick a weight you can lower slowly every rep.
Easier
Go lighter, or hold the static arm a little higher, closer to straight.
Harder
Pause for 1 second at the bottom of each rep on the moving arm, or take 3 seconds to lower.
Try it: 3 sets of 12 to 15 reps per side, or 30 seconds on and 30 off.
What does iso hold mean in a workout?
Iso is short for isometric: you hold a position without moving. In this move, one arm holds the dumbbell still halfway down while the other does reps, so your triceps never get a break.
