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

21s are a classic biceps training method that use partial and full ranges of motion in one extended set to maximize pump, tension, and muscle growth. The most common version is done with an EZ curl bar, performing 7 reps in the bottom half of the movement, 7 reps in the top half, and 7 full-range reps… all without rest.

This makes them an excellent hypertrophy and finishing technique.

Primary Muscles Worked: Biceps Brachii
Secondary Muscles Worked: Forearms (Brachioradialis, Grip)
Equipment Needed: Barbell, EZ-Bar, or Dumbbells

---

How To Do 21s

Step-by-Step Instructions

1. Set-Up:
   • Stand tall holding a barbell, EZ-bar, or dumbbells with an underhand grip.
   • Keep your arms fully extended and elbows tucked close to your sides.
2. Execution:
   • First 7 reps: Curl starting from the bottom up to halfway (elbows at 90°).
   • Next 7 reps: Curl starting from the top to down to halfway (90° to full contraction).
   • Final 7 reps: Perform full-range curls from bottom to top.
3. Tips for Proper Form:
   • Keep your elbows pinned to your sides; don’t swing them forward.
   • Use a controlled tempo; don’t rush through the reps.
   • Focus on squeezing the biceps at the top of each rep.

---

Key Benefits

• Creates extended time under tension for hypertrophy.
• Produces a strong biceps pump and metabolic stress.
• Can be used as a finisher or intensity technique without requiring heavy weight.

---

Modifications and Variations

• Easier Option:
  • Use lighter weight to maintain form throughout the set.
  • Perform fewer reps per range (e.g., 5-5-5 instead of 7-7-7).
• Harder Option:
  • Slow down the eccentric phase of each rep.
  • Add isometric holds at 90° during each range.
  • Perform 21s with different curl variations (hammer curls, preacher curls, cable curls).

---

Common Mistakes

• Using Momentum: Swinging the bar reduces biceps tension.
• Partial Range Done Incorrectly: Be strict: first 7 are bottom half, next 7 are top half, then full range.
• Too Heavy a Load: Choose weight that allows good control across all 21 reps.

---

Reps and Sets Recommendations

• For Hypertrophy/Finisher: 2–3 sets of 21 total reps (7-7-7).
• As Accessory Work: 2 sets at the end of an arm workout to maximize pump.
• For Variation: Rotate between barbell, dumbbell, and cable 21s in different sessions.

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.

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.

Share This