Weight and reps
Single-Arm Dumbbell Bench Press
The single-arm dumbbell bench press is a flat press with one dumbbell, so one side of you is loaded and the other is not. Your trunk has to stop the weight pulling you off the side of the bench, which makes it as much a core exercise as a chest one — and it shows you plainly whether one arm is weaker than the other.
How to do it
- Lie flat with your feet planted wide and your free hand on your stomach or holding the bench.
- Lower the dumbbell to the side of your chest with the elbow about 45° from your body.
- Press up over your shoulder, keeping both shoulder blades on the bench.
Common mistakes
- Letting the free shoulder lift off the bench as your body twists toward the dumbbell.
- Starting with your strong arm and giving it more reps than the weak one can match.
What it trains
- Chest
- presses the dumbbell up and slightly in on the working side — the prime mover
- Triceps
- extend the elbow through the top of the press
- Front delts
- assist off the chest and steady the dumbbell over the shoulder
- Obliques
- stop the load twisting your torso and pulling you toward the working side
Variations and alternatives
Common questions
Do I log both arms?
No, log the reps of one arm and the weight of the one dumbbell. Eight with each arm is a set of eight. StackUp judges your heaviest set against your rep range, so logging the total of both arms would suggest an increase neither arm has earned.
Why does the dumbbell pull me off the bench?
Because all the load sits on one side and tries to roll you toward it. Plant your feet wide, press them into the floor and brace as if someone were about to shove you sideways off the bench. If you still slide, hold the bench with your free hand until your trunk catches up.
Should I use the same weight as on my dumbbell bench press?
Start a step or two lighter than you use per hand with two dumbbells. The chest does the same job, but your trunk now has to hold you still, and early on that is what gives out first. StackUp suggests increases in 2.5 kg steps by default; if the dumbbells in your gym go up in 2 kg steps, change the step for this exercise.
Should I finish one arm before switching?
Yes — with a single dumbbell there is no sensible way to alternate. Start with your weaker arm and let what it manages set the reps for the stronger one, so the gap closes instead of growing.
In StackUp. Logged as weight and reps per set, and your heaviest working set decides whether the weight goes up next time. Get the app.
Chest
