Dumbbells vs Kettlebells: Which Is Best for Building Muscle?

A client comes to you and says that they want to start weight training. Their primary goal is to increase muscle strength. So, they're wondering which type of free weight is best for this purpose: a dumbbell or a kettlebell. How do you respond?

If you look at the research, it's easy to see that one is not overtly superior to the other. Instead, both types of weight offer value when it comes to building maximal strength. Yet, there are still times when one weight may be preferred over the other.

Building Muscle with Dumbbell Exercises

Several studies have connected the use of dumbbells with increased muscle size and strength. Many have even found that the use of these devices provides similar results as other types of resistance training.

For example, one study noted that using a dumbbell is just as effective as working out with resistance bands. Specifically, it was just as good at activating muscle when performing a lateral raise, wrist extension, and shoulder external rotation.

Another piece of research compared doing a chest press with a machine, barbell, or dumbbell. All three pieces of equipment showed similar electrical activity within the deltoids and pecs.

Some studies have even looked at whether any differences exist when using one dumbbell over two. While both types of movements can improve strength, one study noted that doing a unilateral bench press—an exercise that involves lifting one dumbbell at a time—was better than using two for improving range of motion.

A dumbbell workout enables you to work multiple muscle groups. A solid upper body dumbbell workout includes exercises such as a bicep curl, shoulder press, and bent over row. A goblet squat, single-leg deadlift, and walking lunges are dumbbell exercises that work the lower body.

You can also add dumbbell weight to your core strength routine. A strong core supports better posture, reducing your risk of back injury and pain. Research has also connected increased core strength with reduced falls as you age.

Kettlebell Workout and Muscle Strength

Adding a kettlebell exercise or two (or more) to your fitness routine provides strength advantages too. One study noted that working out with these weights increases the strength of trunk extensor muscles, for instance. These muscles work in tandem with trunk flexors to support proper posture.

Participants in this study reported other benefits as well. These included lower levels of pain in the neck, shoulders, and low back. That makes this workout option good for individuals with this same type of pain.

Another piece of kettlebell research compared using these free weights with traditional resistance training. In this case, the training involved using heavy weight. Both types of weight offered improvements in strength and power.

Though, it should be noted that subjects lifting the heavier weight did see larger gains. This doesn't mean that the use of a kettlebell won't enable clients to reach their fitness goals. More so, it suggests that if a client wants to achieve major gains in muscle strength and size, a different strength routine may be best.

Realistically, a dumbbell routine will likely have the same issues since there are limits to the amount of weight that can be lifted. Therefore, both forms of free weight are equal in this regard.

When Using a Traditional Dumbbell May Be Best

Although the use of a dumbbell and kettlebell can both improve strength, there are some instances in which a dumbbell may be the better choice.

Because the weight in a dumbbell is even on both sides, these devices can allow for a more fluid movement. It might feel easier for the client to control, thus not compromising their form.

Additionally, a dumbbell is designed to be lifted with one hand. That makes this weight good for both unilateral exercises and bilateral exercises. For example, you can work one bicep at a time by doing alternate curls or you can work both biceps simultaneously by lifting both dumbbells at the same time.

Not that you can't do the same with a kettlebell, because you can. However, it may feel a bit more awkward since the weight isn't distributed the same.

When to Consider Kettlebell Training Instead

If clients prefer doing exercises that involve the use of two hands, a kettlebell is more suited for this position. Though, doing one-handed exercises, like the kettlebell snatch, are effective too. This single kettlebell movement is good for increasing strength in your hamstrings and glutes.

A kettlebell may also be better when doing some exercises because, instead of the weight being evenly distributed to the sides, it sits in the middle, directly under the handle. This makes certain moves easier to perform. The kettlebell swing is one. This exercise is good for building muscle all over the body, but primarily for strengthening the back and hips.

There's also the fact that many kettlebell exercises are often more explosive. They involve more than just standing there while lifting and lowering weights. That makes this piece of equipment better for people who want to increase power along with strength. Clients participating in sprinting, speed skating, and wrestling are a few to consider.

Which Weight is Best for a Home Gym?

Ideally, a home gym would include a set of dumbbells and a set of kettlebells. However, this isn't always possible, both due to cost and the amount of available space. Which type of weight should a client purchase if they must choose one over the other?

One benefit of going with dumbbells is that, if they don't have a lot of room, they can get an adjustable dumbbell set. This enables them to increase or decrease resistance without having to purchase a lot of different weights.

Yet, if the client wants to also lose weight, a kettlebell may be a better investment because this weight doubles as a cardio device. One study even found that doing kettlebell swings were as effective as running on a treadmill when it comes to heart rate and rate of perceived exertion.

The Final Word on Dumbbells vs Kettlebells

Both a dumbbell and kettlebell can be used as part of a complete exercise routine. Incorporating each type of training offers clients desired strength gains. These trainings can be combined in the same workout session or they can be alternated, doing dumbbell exercises one time and kettlebell movements the next.

Teaching personal training clients how to include both forms of free weight into their exercise regimen works their muscles in a different way. It also prevents them from getting bored because their routine is constantly changing.

One way to reinforce your expertise in strength training is with certification. The ISSA's Strength and Conditioning certification tells prospective clients that you have advanced knowledge in this area. It says that, as a personal trainer, you build the best strength, agility, and conditioning training that sports science has to offer!