The dumbbell preacher curl is a great exercise for building your biceps because it lets you train each arm independently. As such, the movement also helps you to achieve a stronger mind-muscle connection because you only need to focus on working one bicep at a time.
Furthermore, the single arm preacher curl is an excellent exercise for sculpting proportional arms because by training each bicep separately, you're less likely to develop muscle imbalances.
The following tutorial shows you how to perform preacher curls with dumbbells. You'll then learn the main advantages that this exercise holds over regular preacher barbell curls, as well as the different variations that are possible.
Dumbbell preacher curl exercise details
- Main Muscles: Biceps brachii
- Secondary Muscles: Brachialis, brachioradialis, forearm flexors
- Exercise Type: Strength
- Exercise Mechanics: Isolation
- Difficulty Level: Beginner
- Equipment Needed: Dumbbells, preacher pad, weight plates.
How to do dumbbell preacher curls
- Grab a dumbbell and then sit on the preacher curl station seat.
- Brace one arm against the sloped side of the preacher pad.
- Allow your bicep to stretch out so that your elbow is fully extended.
- Curl the weight toward your front delts and squeeze your biceps as forcefully as you can.
- Lower the dumbbell under control until your elbow is once again locked out.
- Repeat the motion for your other arm and perform 3-5 sets of 8-15 reps per arm.
Dumbbell preacher curl advantages
Regular arm curls can certainly build size and are undeniably more convenient than DB preacher curls because you don't need access to a preacher curl bench. However, one arm dumbbell preacher curls offer some distinct advantages that traditional bicep curls simply can't provide.
Enhanced bicep isolation
The one arm preacher curl provides virtually unrivaled bicep isolation because you only need to focus on working one bicep at a time. This results in a stronger mind-muscle connection because you can channel all of your energy into blasting the bicep that you're currently training.
Ultimately, you'll build bigger biceps by using dumbbells (and especially by training each arm separately) because a larger majority of the tension will be going to the target muscles.
However, if you want to emphasize your brachioradialis rather than your biceps, then you can click the link to learn how to do hammer preacher curls with the optimal muscle-building form. It's recommended to incorporate both movements into your routine so that you can achieve good overall arm development.
Fewer muscle imbalances
Most of us have a dominant arm that's naturally stronger than that of our weaker side. So in this sense, muscle imbalances are nothing to stress over.
However, taken to the extreme, muscular imbalances can impact your sporting and gym performance. Similarly, if you're a bodybuilder, having a mismatch in bicep size can compromise the symmetry of your physique and diminish your upper body aesthetics.
The trouble is that barbells—as good as they are at building mass—can often worsen your muscle imbalances because your dominant arm will naturally perform most of the lifting due to its extra strength.
Using dumbbells is the solution. Single arm preacher curls let you hone in on each arm to ensure that both sides of your body are receiving equal work. Specifically, you can improve the symmetry of your biceps by making sure that you perform the same number of repetitions for each arm.
But if you have particularly noticeable size differences between your biceps, then you can actually do a few extra reps or an extra set of preacher DB curls for your weaker arm so that it can catch up to your stronger side.
Less forearm strain
Barbells force your forearms into a fully supinated position throughout the entire repetition. This is unlikely to cause any issues if you're lifting relatively light and performing low training volumes.
However, once you become stronger at the DB preacher curl (presuming that you don't rotate the weight) and start increasing the training volume as well, then you might run into problems such as splints and tendonitis because curling with fully supinated palms puts the forearms in a very unnatural position.
With a proper dumbbell preacher curl, on the other hand, you can still enjoy the benefits of contracting your biceps with a fully supinated forearm. But you can also rotate your lower arm on the way down (basically into a hammer curl position) so that you don't place excessive amounts of strain on your forearm flexors.
Alternatively, you can perform preacher curls on the cable machine if you want an exercise that provides constant tension and more joint-friendly resistance.
Dumbbell preacher curl variations
There are two main types of preacher dumbbell curls. Each variation works the exact same muscles, but one is more convenient while the other provides better bicep isolation.
One arm dumbbell preacher curl
The single arm preacher curl is the exercise that I most recommend performing if you have the time—and especially if you have muscular imbalances.
As mentioned, the one arm preacher curl lets you focus 100% of your attention on training each bicep independently. This leads to a more potent muscle growth stimulus by way of an improved mind-muscle connection because by honing in on each bicep, you can be sure that the target area is receiving all of the tension.
The only downside is that single arm preacher curls are slightly inconvenient to perform if you're pressed for time. However, for most bodybuilding enthusiasts, the enhanced muscle isolation will be more than worth the extra time this exercise adds to your gym session.
Two arm dumbbell preacher curls
If you already have a top-tier mind-muscle connection from years of training, then two-arm dumbbell preacher curls are the way to go. This exercise is more convenient than the one arm dumbbell preacher curl because you're training both arms at the exact same time.
However, both arms are still working independently. It's not like your stronger arm can help your weaker arm lift its dumbbell because your dominant arm is already holding its own dumbbell!
As such, the two-arm variation is both time-efficient and excellent for building a proportional physique. Just be sure to get a full range of motion because DB preacher curls provide the most tension when your elbows are close to lockout  and comparatively less tension in the contracted position. 
The only drawback is that you can't quite achieve the same quality of mind-muscle connection when you have to focus on two arms instead of just one.
Conclusion: How good are DB preacher curls for building your biceps?
The dumbbell preacher curl is the dark horse of arm exercises. Not only does it enhance your upper body symmetry by ensuring that both of your biceps receive equal work, but it also reliably adds mass because you can focus all of your attention on maximally isolating each arm.
Stick to the single arm preacher curl if you want to improve your muscle imbalances. The one-arm version lets you dedicate all of your effort and strength toward ensuring that each of your arms gets the tension that it needs to grow.
- Oliveira, L. F., Matta, T. T., Alves, D. S., Garcia, M. A. C., & Vieira, T. M. M. (2009). Effect of the shoulder position on the biceps brachii emg in different dumbbell curls. Journal of Sports Science and Medicine, 8(1), 24–29. https://pubmed.ncbi.nlm.nih.gov/24150552/
- Barakat, C., Barroso, R., Alvarez, M., Rauch, J., Miller, N., Bou-Sliman, A., & De Souza, E. O. (2019). The Effects of Varying Glenohumeral Joint Angle on Acute Volume Load, Muscle Activation, Swelling, and Echo-Intensity on the Biceps Brachii in Resistance-Trained Individuals. Sports, 7(9), 204. https://doi.org/10.3390/sports7090204