21s (How To Do The Best Curl Exercise Ever Invented)

21s are one of the best curl exercises ever invented. It’s basically a superset of all curls – a set of seven of two half-range reps (both bottom and top) and then seven full reps to finish.

In this guide, I’m going to teach exactly how to do 21s, explain what muscles it works and provide you with a few alternatives.

How To Do 21s

Equipment Needed

  • Barbell (Curl Bar will also work great if you have one)

Step-by-Step Instructions

  • Grab a bar – either a barbell or a curl bar – with a supinated (palms up) grip.
  • Have a partner place their hand at the bottom of your sternum.
  • Now curl the bar up to your partner’s palm, lightly tapping it each rep. This should equate to about half a full rep.
  • Once you’ve completed seven reps, curl the bar all the way to the shoulders.
  • Your partner should now flip their hand over, palm facing up.
  • Now lower the bar down, lightly tap your partner’s palm again, and curl back up. This should equate to about half (the top half now) a full rep.
  • Once you’ve completed seven reps, have your partner remove their hand and lower the bar back to your thighs.
  • Finish the set of 21s with seven full reps – all the way up and down.

Coaching Points

First, a word of advice to the “partner”. Always have your palm facing the bar because if the lifter loses control of the rep and whacks the back of your hand it hurts. Trust me on that one.

If you don’t have a partner, use a mirror. If you don’t have a partner or a mirror, just make your best estimation of ‘halfway’. At the end of the day, you’re still going to be doing 21 reps. It’s going to burn.

This probably goes without saying, but you’re going to end up using considerably less weight than you would for a normal ‘set of 10’. Go light to start out and stay strict with your form.

Muscles Worked

Biceps. All of the biceps. Seriously though, biceps.

Benefits of 21s

Flexed Biceps

21s can bring a ton of great benefits to your workouts. Here are just a few:

Enhanced Muscular Endurance

With 21 total reps per set, you’re pushing your muscles to work harder for longer periods, improving muscular endurance.

Increased Time Under Tension (TUT)

Performing 21 reps with controlled movement increases the time your muscles are under tension. TUT is a key factor in hypertrophy (muscle growth).

Overcome Plateaus

If you’re stuck in your bicep development, 21s can help break through plateaus by providing a different stimulus to your muscles.

Alternatives for 21s

First off, why on Earth would you want an alternative to 21s? It’s the best possible curl exercise.

If you’d like additional alternatives to the exercises listed below, check out these alternatives to 21s.

Dumbbell 21s

If you don’t have a bar, you can still do 21s. If you have dumbbells, just do DB 21s. You may not be able to use a partner as a guide in the same way as with a bar, but don’t let that stop you. Do 7 reps halfway up, seven halfway down, seven full reps and enjoy that beautiful pump.

4 x 4s

It’s hard to have alternatives for 21s because it’s hard to replicate the ‘deep burn’ that 21s create. 4 x 4s are one of those rare exercises that do.

To do 4 x 4s, grab a dumbbell in each hand. Hold one dumbbell out in front of your waist by bending your elbow at a 90-degree angle. Keep holding that dumbbell in place while you do 4 curls with the other arm. Switch and do the same on the opposite side. Finally, finish with four reps on both arms.

Barbell Curl Drop Set

Drop Sets are another way to maximize that end-of-workout pump that is so awesome leaving the gym with. Grab a bar and add a few small plates on each side. For example, two ten-pound plates on each side (adjust as needed).

Perform 10 reps and then quickly take one plate off each side. If you have a partner you can have them remove weights so you don’t even have to set the bar down (this is optimal). Perform 10 more reps, take off the other ten-pound plate and finish with 10 reps of just the bar.

If I’m introducing you to drop sets for the first time, you’re welcome, I just changed your life.

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More Links and Info

For more exercises to crush your Biceps and Triceps, make sure to check out the Arm Farm section of our exercise library.

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