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Tricep 21s exercises and workout

Learn how to do tricep 21s on skull crushers, overhead extensions, pushdowns, and more.
Written By  James Jackson
Last Updated on 2nd May 2022
A man doing the tricep 21s exercise during his workout

Tricep 21s are a great intensity technique for making your existing tricep exercises more challenging. Tricep twenty ones don’t take long to perform, so they can really help to speed up your workouts by enabling you to perform plenty of quality training volume in a relatively short space of time.

This guide shows you how to do tricep 21s on a number of different exercises and then walks you through a full workout routine.

Related: Bicep 21s

What are tricep 21s?

What are tricep 21s exactly? Tricep 21s are an intensity technique used by bodybuilders and weight training enthusiasts who want to make their triceps bigger and more muscular. The principle is pretty simple; you perform 7 reps in the bottom position of an exercise, 7 reps in the top position, and then 7 full range of motion reps for a total of 21 reps. That’s tricep 21s in a nutshell.

What exercises can you do tricep 21s on?

Tricep 21s are naturally best suited to isolation exercises so that you can make your triceps do all of the work. Sure, you could do them on close grip bench presses, but you really don’t want to get stuck under the bar when your triceps are massively fatigued (as they will be when you do 21s).

Skull crusher 21s

A man doing skull crusher 21s for his triceps

You can use any equipment you like for skull crusher 21s. I recommend dumbbells the most because they enable you to keep your wrists in a joint-friendly neutral position while ensuring that both of your arms get similar amounts of work.

To do 21s on skull crushers, lower the weights all the way behind your head so that you feel a massive stretch in the long head of your triceps. Then, come just less than halfway up. Repeat this 7 times.

Next, perform 7 reps in the top half of the range of motion by lowering the weights halfway down and then lifting them all the way back up so that elbows are fully locked out.

Finally, do 7 full skull crusher reps.

Overhead extension 21s

A man doing tricep 21s on the overhead tricep extension

Like skull crusher 21s, overhead extension 21s train the long head of your triceps by putting your shoulders into flexion (the long head is the only triceps muscle that crosses the shoulder joint).

Again, dumbbells are your best choice here so that you can build balanced tricep muscles. I like to train each arm separately during overhead extensions—especially during 21s—so that I can bring forth the best possible mind-muscle connection and make sure that I’m using a proper range of motion.

Begin by lowering the dumbbell behind your neck. Go as low as you comfortably can, and then flex your triceps to lift the weight halfway back up. Repeat this 7 times.

Next, lift the weight all the way back up and then lower it halfway down. Once you’ve lowered the weight halfway, flex your triceps to lift it back up. Keep going until your elbow is locked out.

Finish this triceps 21s exercise by performing 7 full overhead extension reps. Repeat the set with your other arm.

Tricep pushdown 21s

A man doing tricep pushdown 21s

If you want to get a great tricep pump while keeping your elbows more or less out of trouble, then tricep pushdown 21s are the exercise for you.

I like using the rope attachment so that I can spread the ends of the rope and get a really intense contraction.

To do rope pushdown 21s, you first want to push the attachment all the way down so that your elbows are locked out. Then, release the contraction in a controlled manner and allow the rope to travel halfway up. Immediately perform another half rep to keep the tension on your triceps. Do a total of 7 reps here.

Then, allow the rope to travel all the way back up so that your forearms are pressed against your biceps. Next, push the rope halfway down by flexing your triceps. Once you’re at the halfway point, slowly release the contraction to move the rope back up.

Finally, perform 7 full pushdown reps.

Diamond push-up 21s

A man doing 21s for his triceps

If you haven’t got any equipment but still want to do a tricep 21s workout, then diamond push-up 21s are a great exercise that you can do pretty much anywhere.

I’m warning you, though. Diamond push-up 21s are very challenging, especially when you do multiple sets.

Start by getting into the proper diamond push-up position; hands together, legs extended all the way back, core tight, back straight. Then, lower your chest all the way to the ground by bending your elbows. Push yourself halfway back up. Repeat 7 times.

Next, lock your elbows out and lower your body halfway down toward the ground. Stop at the halfway point, and then flex your triceps to push yourself back up. Keep going until your elbows are fully extended.

Finish the 21s set by performing 7 full diamond push-up reps—if your triceps can manage it.

Tricep 21s workout routine

I personally like to pick one triceps 21s exercise and use it as a tricep burnout at the end of my workout. But if you’re looking for a standalone high-rep routine to pump up your triceps, then this 21s tricep workout will do the job very well.

Performing 21s for your triceps is highly challenging, so don’t do more than 3 sets per exercise.

1: Overhead extension 21s — 2-3 sets

2: Rope pushdown 21s — 2-3 sets

3: Skull crusher 21s — 2-3 sets

Conclusion: Should you do 21s for your triceps?

A man doing the 21s exercise for his triceps

If you’re a beginner? Probably not. Novice lifters should build a solid foundation of size and strength before they start doing intensity techniques like twenty ones for their triceps.

If you’re an intermediate or advanced lifter, however, then tricep 21s are a great way to get extra arm-pumping training volume into your routine. They also test and improve your mental toughness because your triceps will be really burning after doing all 21 reps.

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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