Single-Arm Dumbbell Bench Press: Core Strength Hidden in a Press
The single-arm dumbbell bench press is a normal flat dumbbell press done with one weight instead of two. Because the load sits on one side only, your body wants to twist and roll off the bench towards the dumbbell. Stopping that from happening is the point. Your chest, front shoulder and triceps press the weight, while your trunk, hips and the opposite side of your body work hard to keep you square. It is a good choice for anyone who wants pressing strength and a stable midsection from the same exercise, for exposing a weaker side, and for anyone who finds two dumbbells awkward to get into position.
It does not replace a heavy two-handed press for building maximum chest strength. You will always handle less weight on one arm than half of what you could press with two. Think of it as a press with a built-in core exercise, not as the main event.
Why one dumbbell changes the exercise
With two dumbbells, the loads balance each other. Your torso stays put more or less by default. Take one away and the weight acts like a lever trying to rotate you around your spine. To resist it, the obliques and deep trunk muscles on the opposite side switch on, your free-side glute presses into the bench, and your feet push into the floor.
Trainers call this anti-rotation work. The same principle sits behind the cable exercise covered in our guide to the Pallof press. The difference is that here you are also pressing a meaningful load, so you get two training effects for the time of one.
There is a second benefit. When you press with both arms, a stronger side can quietly do more of the work. On one arm there is nowhere to hide. If your left arm struggles at eight reps where your right managed twelve, you have learned something useful.
How to do it, step by step
- Pick a modest weight. Start with around the dumbbell you would use for each hand in a normal two-dumbbell press, or slightly lighter. The balance demand is the surprise, not the pressing.
- Get into position. Sit on the end of the bench with the dumbbell on your thigh. Lie back and bring it to the side of your chest, elbow under the wrist.
- Set your base. Plant both feet wide and flat. Squeeze both glutes. Draw your shoulder blades gently back and down so your upper back is pinned to the bench.
- Use the free hand sensibly. Either rest it on your stomach or hold the side of the bench lightly. Holding the bench hard makes it easier. Hands off is the stricter version.
- Brace. Take a breath into your stomach and tighten as if someone were about to prod you in the ribs. Our guide on how to brace your core covers this in more detail.
- Press. Push the dumbbell up over the shoulder, keeping your hips and the opposite shoulder flat. Finish with the arm straight and the wrist stacked over the elbow.
- Lower under control. Take two or three seconds to bring it back down to the side of the chest, elbow at roughly 45 degrees from your body.
- Switch sides. Finish all reps on one side, then swap. Start each session with your weaker side and match its reps on the stronger one.
Common mistakes
| Mistake | What it looks like | Fix |
|---|---|---|
| Rolling towards the weight | The non-working shoulder lifts off the bench | Lighter dumbbell, wider feet, squeeze the opposite glute |
| Elbow flared to 90 degrees | Upper arm straight out from the body | Tuck to about 45 degrees; the shoulder will thank you |
| Rushing the lowering | Dumbbell drops and bounces | Count two to three seconds down |
| Gripping the bench to cheat | Free hand white-knuckled on the frame | Rest the free hand on your stomach once you are confident |
| Lower back arching hard | Ribs flare up, hips lift | Breathe, brace, keep ribs down and glutes on the bench |
Sets, reps and where it fits
Because the exercise is limited by stability as much as strength, it suits moderate weights and controlled reps. Two to four sets of eight to twelve per side works well for most people. Heavy sets of three or four reps tend to turn into a wrestling match with the bench, which is neither safe nor productive.
There are three sensible places for it in a programme:
- As your main press on a lighter day, after a heavier barbell or two-dumbbell press earlier in the week.
- As a second press after your main one, where its core demand adds something new.
- As a stand-in when a full press is not appropriate, for example on a day when one shoulder is cranky and the other is fine, provided the cranky side is pain-free with the lighter load.
If you are deciding between barbell and dumbbell pressing in general, our comparison of dumbbell and barbell bench press lays out the trade-offs. The single-arm version sits alongside both, rather than competing with either.
Making it harder or easier
The obvious way to progress is more weight, but there are better levers to pull first:
- Feet closer together. A narrower base gives your hips less leverage and makes your trunk work harder.
- Feet up. Knees bent with feet off the floor removes the legs from the job almost entirely. This is an advanced variation; use a light weight.
- Pause at the bottom. A one-second hold with the dumbbell beside your chest increases the time your trunk is fighting rotation.
- Half on the bench. Lying with the working-side shoulder blade off the edge of the bench is a variation some coaches use for advanced clients. It is very demanding and not one to try on your own.
To make it easier, hold the bench with the free hand, keep feet wide, and reduce the weight. If the bench itself is not available, a single-arm floor press gives you a similar anti-rotation challenge with a shorter range of movement.
Who it suits, and who should check first
It works well for people with an obvious left-right difference, desk workers who rarely load their trunk, and anyone who trains for sport, where force usually travels through one side of the body at a time. It is also handy for beginners who struggle to get two heavy dumbbells into position safely.
Check with your GP first if you have a shoulder injury, recent surgery, a heart condition, are pregnant, or are coming back after a long break from exercise. Pressing with a braced trunk raises your blood pressure briefly, and that matters for some people.
On a coached session, I use this lift to see how a client organises their body under an uneven load: whether the hips stay still, whether the free shoulder lifts, and which side tires first. That tells me a good deal about what the rest of their training needs. If you want that kind of attention, the details of private 1-1 training in Highgate are on our training page.
Questions we get asked
Is the single-arm press better than the normal dumbbell press?
Not better, different. The two-dumbbell press lets you move more total weight for the chest. The single-arm version trains the chest less heavily but asks much more of your trunk and exposes side-to-side differences.
How heavy should I go?
Start at or a little under the dumbbell you use per hand in a normal press. If your opposite shoulder lifts off the bench, the weight is too heavy for now.
Should I alternate sides each rep?
You can, but finishing one side fully keeps the core under tension for longer and makes it easier to compare sides. Alternating is a reasonable variation once the basic version is solid.
Can it fix a strength imbalance?
It can help, alongside other unilateral work, by making sure the weaker side does its full share. Small differences between sides are normal and not a problem in themselves. If a difference comes with pain, see a GP or physiotherapist, and you can ask about coached sessions with Artem once you are cleared.
Book with The Highgate House
Ready to start training properly? Email us at [email protected] with the service and the day that suits you, and we will come back to you with times.
Visit The Highgate House · Private personal training
The Highgate House, Archway Road, Highgate, London N6.
