Muscles worked
Here one triceps works at a time, and as in the two-handed version, the long head is stretched when your arm is overhead. Each arm has to handle its own weight, so a stronger side cannot hide a weaker one. Your trunk also gets more to do, as a load on one side tries to pull your upper body off line. Your free hand can rest against the working upper arm to help it stay still.
Common mistakes
- Leaning to one side. With weight in only one hand, it is easy to tilt your upper body to get the dumbbell up. Stand tall with your abs braced, or sit on a bench with a backrest.
- The free hand joins in. The supporting hand tends to start pushing the arm up once the set gets heavy, and your triceps then do less than you think. Keep that hand light, and drop the weight if it has to help.
- Letting the strong arm go first. Your stronger side then sets the target, and the weaker one chases it with worse form. Start with your weaker arm and match the reps with the other.
Variations and alternatives
- The overhead triceps extension with both hands on one dumbbell, when you want to use more weight.
- The overhead cable extension can be done one-armed with a single handle and gives smoother resistance.
- The single arm pushdown also works one arm at a time but with your arm by your side, if overhead work feels awkward.
Sets and reps
Use a light dumbbell: heavy, low-rep sets are hard to control when one arm carries the weight behind your head. To build muscle, 10 to 15 reps per arm over 2 to 3 sets works well, with 15 to 20 for endurance. Many people switch arms straight away and rest once both sides are done. The guide to sets and reps covers the basics of choosing.
When your weaker arm reaches the top of the range on every set, it is time for the next dumbbell. Small jumps between dumbbells, or an adjustable one, let you progress a little more often. That is how progressive overload works when each arm trains on its own.