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How to do an alternating dumbbell lying triceps extension

Learn how to isolate your triceps with the alternate lying dumbbell extension.
Written By  James Jackson
Last Updated on 10th October 2021
A man doing an alternate lying dumbbell extension for his triceps

The alternating lying dumbbell tricep extension trains all three heads of the triceps and ensures that both of your arms are receiving similar amounts of work, which in turn helps you to sculpt a more proportional upper body.

This tutorial shows you how to do an alternate lying dumbbell extension and then discusses the pros and cons of the exercise so that you can decide if it’s right for you.

Related: One arm lying cross body tricep extension

Alternating dumbbell lying triceps extension exercise details

How to do an alternate lying dumbbell extension

  1. Grab a relatively light pair of dumbbells with a neutral grip.
  2. Lie on a weight bench with your feet planted firmly on the floor.
  3. Press the dumbbells up so that they’re positioned directly over your face.
  4. Lower one of the dumbbells behind (or to the side of) your head by breaking at your elbow.
  5. Descend until you feel a strong triceps stretch.
  6. Flex your triceps to lift the dumbbell back up. Keep going until your elbow reaches full extension.
  7. Do the same with your other arm; lower the weight behind your head and lift it back up by flexing your triceps.
  8. Perform 3-5 sets of 8-20 reps per side.

Alternate lying dumbbell extension advantages

The alternate lying triceps extension has three major advantages that can really enhance the appearance of your arms when you perform it consistently and with the proper form.

Trains your triceps equally

A man with symmetrical triceps

Like the incline dumbbell extension, the alternate lying triceps extension ensures that both of your arms receive roughly equal amounts of work and thus grow at similar rates.

This is because when you use dumbbells, you have to lift each weight independently. So even if your more muscular arm was tempted to dominate the movement or do more of the work it couldn’t; it’s already preoccupied with lifting its own dumbbell.

So if you want your triceps to look symmetrical as well as big and muscular, then the alternate lying dumbbell extension is a great exercise to include in your routine.

There is, of course, a good chance that you’ll still have a stronger mind-muscle connection with your dominant triceps muscle. So that muscle may still receive slightly better stimulation even if you’re performing the same number of reps with each arm, purely because you can place more tension on that particular triceps muscle.

Increases your training volume

A man performing an alternating dumbbell lying triceps extension

Doing enough training volume is critical for making your muscles bigger, stronger, and more toned.

But sometimes, you don’t want to spend extra time in the gym in order to do additional sets.

Well, with the alternating dumbbell lying triceps extension, you don’t have to!

Since you’re training your triceps in an alternating fashion, each of your triceps gets a brief rest while the other is working. As such, you’ll be able to perform more reps on each set, which is to say accumulate more training volume because your triceps will be fresher for each of their repetitions.

While lifting the dumbbells in an alternating fashion doesn’t dramatically jack up the training volume, you’re still getting extra stimulation without doing any more sets or any extreme workout techniques.

That’s what you call a sound tricep training investment.

Works all three heads

A man showing the three heads of the triceps brachii muscle

Due to the elbow extension component of the exercise, the alternate lying dumbbell extension trains all three heads of the triceps, which means that it’s highly effective for building overall mass.

Yet, because you’re lowering the weights behind or to the sides of your head (rather than directly to your face), the movement also has a significant shoulder flexion component to it.

This is good news for your triceps because the long head of the triceps, which is the largest of the three heads, acts on the shoulder joint as well as the elbow joint.

So by allowing some backward shoulder movement as you lower the weights, you’re putting the long head of your triceps under an excellent eccentric stretch, which will naturally translate into more muscle growth when you do the exercise regularly.

Alternate lying tricep extension disadvantages

Alternating lying dumbbell extensions, as you’ve learned, are very effective indeed for training the triceps. However, the alternate lying dumbbell extension isn’t just sunshine and rainbows; there are a few downsides that you need to take into consideration before deciding whether or not the exercise is right for you.

Harder to count reps

A man doing a lying alternate dumbbell tricep extension

During alternating dumbbell lying triceps extensions, you can either count total reps or reps per arm.

I find the former counting option a bit easier because I think it’s more natural to count upwards rather than 1,1,2,2, etc.

However, counting the reps separately for each arm could give you a psychological advantage in that your sets will seem sorter because the total number of reps will seem lower.

Ultimately, there’s not a whole lot of difference between the two methods. Try both options and see which you find easier.

As an aside, if you don’t have access to a bench, then you can also do an alternating lying tricep extension on the floor, which is a particularly useful exercise if you train at home.

Reduced mind-muscle connection

A man performing a lying alternating dumbbell triceps extension

Lifting weights in an alternating fashion can take some getting used to when you’ve been doing exercises like the decline tricep extension and the pronated triceps extension that require you to lift both weights at once.

It can be challenging to focus on lifting two dumbbells in quick succession because your brain constantly has to switch back and forth between different limbs.

Add in the fact that counting repetitions is a bit more cumbersome on alternating exercises, and you can see why the strength of your mind-muscle connection could take a hit.

Of course, if you’ve been lifting for years, then your training experience might be enough to override this theoretical reduction in mind-muscle connection.

But still, if you want to do everything in your power to give your triceps the best possible workout, then it’s recommended to do a single arm lying tricep extension instead because you can train each arm completely separately during unilateral exercises (the side leaning tricep extension is another good choice in the regard).

Conclusion: Are alternating lying tricep extensions worth your time?

Alternating lying tricep extensions are a good way to sneak extra training volume (by way of more reps per set) into your arm routine without actually spending more time in the gym or doing any additional sets.

This is because you’re giving your triceps a short rest in between reps, which naturally means that they’re less fatigued by the time their next rep rolls around.

The drawback is that it’s often mentally challenging to constantly switch your focus between your left arm and your right arm. This impaired focus may make it harder to count your reps accurately and could also reduce the potency of your mind-muscle connection.

James Jackson
James Jackson is a personal trainer who uses his expertise in strength and conditioning to create helpful workout tutorials that show fitness enthusiasts how to build muscle while staying safe in the gym. He draws on the latest sports science data as well as tried and tested training techniques to get the best results for his clients without them having to live in the gym.
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