Are 21s better for muscle growth than regular curls?

There is no direct evidence that they are, because no study has compared 21s with regular curls. Treat them as a way to add variety and a hard, high-rep finisher to your arm training, and keep in mind that the total number of hard sets you do each week matters more than the scheme you use.

Which half of the curl matters more?

In a study of untrained women, the arm trained only in the bottom half of a seated dumbbell preacher curl grew more near the elbow and gained more full-range strength than the arm trained only in the top half, while overall biceps growth was similar. A preacher curl loads the bottom of the range much more than a standing curl, so the result does not transfer directly to 21s, but it is a good reason not to rush the bottom-half reps.

How heavy should EZ Bar 21s be?

Use a bar noticeably lighter than you would for regular curls. The right load lets you finish all 21 reps without swinging, with the last few full-range reps feeling very hard.

How many sets of 21s should I do?

One to three sets at the end of an arm or pulling session is a common approach, with about 1 to 2 minutes of rest between sets. Count them toward your weekly biceps volume rather than adding them on top of a full curl workload.

Can I do 21s with a straight bar or dumbbells?

Yes. The same scheme works with a straight bar as in the Barbell Curl, with dumbbells or with a cable. The EZ bar's angled grip is simply easier on the wrists and elbows for many lifters.

EZ Bar 21s

What Are EZ Bar 21s?

EZ Bar 21s are an isolation exercise that primarily targets the biceps and also engages the brachialis, brachioradialis and forearm flexors. They are an intermediate-level movement that turns one set of standing EZ bar curls into 21 reps: 7 through the bottom half of the range, 7 through the top half and 7 through the full range, with no rest between the three parts.

The scheme is a long-standing bodybuilding technique for adding variety and intensity to arm training. Because the set runs continuously for 21 reps, it keeps the elbow flexors under tension for much longer than a normal set of curls and produces a strong pump and burn. That makes 21s a common finisher at the end of an arm or pulling session, usually for one to three sets with a noticeably lighter bar than you would use for regular curls.

In a standing curl the bar feels heaviest when your forearms are parallel to the floor and lightest near the bottom and the top. Both partial ranges pass through that hardest point, which is a big part of why the set gets so demanding by the final full-range reps. The angled EZ bar grip turns the palms slightly inward compared with a straight bar, which many lifters find easier on the wrists and elbows across so many reps. The same scheme also works with a straight bar, dumbbells or a cable.

EZ Bar 21s suit lifters who already curl with strict form and want a change of stimulus or a short, hard finisher. Hitting the same halfway point on every partial rep and keeping the elbows still while fatigue builds takes real control, so newer lifters should first build a solid EZ Bar Curl in straight sets.

Muscles Worked

MuscleActivation

Biceps Brachii: Primary
Brachialis: High
Brachioradialis: Medium
Deltoid: Low
Flexor Carpi Radialis: Low
Flexor Carpi Ulnaris: Low

Instructions

Stand tall with your feet about hip-width apart and hold the EZ bar with an underhand grip on its angled sections, hands about shoulder-width apart.
Let the bar hang at arm's length in front of your thighs with your elbows close to your sides, chest up and core braced.
For the bottom half, curl the bar up until your forearms are parallel to the floor, then lower it under control until your arms are straight. Do 7 reps.
On the 7th rep, stop with your forearms parallel to the floor instead of lowering the bar.
For the top half, curl the bar from that halfway point up to your upper chest, squeeze your biceps, then lower it back to the halfway point only. Do 7 reps.
After the 7th top-half rep, lower the bar all the way until your arms are straight.
For the full range, curl the bar from straight arms up to your upper chest and lower it back to straight arms. Do 7 reps.
Keep your upper arms still and your torso upright for all 21 reps, breathing out as you curl and in as you lower.
Set the bar down after the 21st rep and rest before your next set.

Common Mistakes

Going too heavy
Using your normal curl weight means the last full-range reps turn into swings, so pick a bar you can control for all 21 reps.
Swinging the torso
Rocking the hips or leaning back to get the bar moving takes work off the biceps and loads the lower back.
Losing the halfway point
Letting the stopping point creep up or down blurs the two partial ranges, so stop each partial rep with your forearms parallel to the floor.
Elbows drifting forward
Bringing the elbows forward on the top-half reps shifts work to the front of the shoulders and takes tension off the biceps.
Resting between parts
Pausing or lowering the bar to rest between the three groups of 7 reps breaks the continuous set that defines 21s.
Dropping the bar
Letting the bar fall on the bottom-half and full-range reps lets the elbows snap straight and wastes the lowering phase.

Injuries

EZ Bar 21s are a low risk exercise when performed with proper technique. The load is light, but 21 continuous reps add up to a lot of curling volume, and the elbow tendons and wrists take most of the strain. Doing many sets of 21s, or doing them too often, can leave the front or inside of the elbow sore and irritated. As fatigue builds, the lower back can also be strained if you start leaning back to finish the last reps. The most serious risk is a biceps tendon tear at the elbow, usually from too much weight and letting the elbow snap straight at the bottom.

Pick a bar you can move for all 21 reps without swinging, which is lighter than your usual curl weight, and warm up with a light set of regular curls first. Keep 21s to one to three sets near the end of a session, lower the bar under control on every rep, and keep your core braced so your torso stays upright.

If you cannot finish the set with strict form, cut each part to 5 reps or go back to straight sets of the EZ Bar Curl or Machine Bicep Curl. If the wrists complain, the neutral grip of the Dumbbell Hammer Curl is gentler. To progress, add a small amount of weight once all 21 reps feel controlled, or slow down the lowering phase.

Stop immediately if you feel a sudden pop at the front of the elbow, sharp pain or sudden weakness, and see a doctor if swelling, bruising or a bulge in the upper arm follows. Elbow pain that builds during the set or lingers into the next day is a sign to reduce the load and the number of sets.

Overview

Primary Focus: Biceps
Equipment: Ez bar
Modality: Strength
Difficulty: Intermediate

Alternative Exercises

Frequently Asked Questions

Q: Are 21s better for muscle growth than regular curls?: There is no direct evidence that they are, because no study has compared 21s with regular curls. Treat them as a way to add variety and a hard, high-rep finisher to your arm training, and keep in mind that the total number of hard sets you do each week matters more than the scheme you use.
Q: Which half of the curl matters more?: In a study of untrained women, the arm trained only in the bottom half of a seated dumbbell preacher curl grew more near the elbow and gained more full-range strength than the arm trained only in the top half, while overall biceps growth was similar. A preacher curl loads the bottom of the range much more than a standing curl, so the result does not transfer directly to 21s, but it is a good reason not to rush the bottom-half reps.
Q: How heavy should EZ Bar 21s be?: Use a bar noticeably lighter than you would for regular curls. The right load lets you finish all 21 reps without swinging, with the last few full-range reps feeling very hard.
Q: How many sets of 21s should I do?: One to three sets at the end of an arm or pulling session is a common approach, with about 1 to 2 minutes of rest between sets. Count them toward your weekly biceps volume rather than adding them on top of a full curl workload.
Q: Can I do 21s with a straight bar or dumbbells?: Yes. The same scheme works with a straight bar as in the Barbell Curl, with dumbbells or with a cable. The EZ bar's angled grip is simply easier on the wrists and elbows for many lifters.