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Reviewed March 2026

21s Bicep Curl

BicepsBarbellIntermediateIsolation

Primary

Biceps

Secondary

Forearms, Brachialis

Equipment

Barbell

Difficulty

Intermediate

Type

Pull

Written byMySetPlan Training Team

NASM-CPT, CSCS certified trainers. Every guide is built from peer-reviewed research and real coaching experience.

Use as a finisher or intensity technique for bicep hypertrophy. The 21s Bicep Curl — a isolation pulling movement — is one of the most effective ways to train your biceps, with secondary work on your Brachialis and Brachioradialis.

Everything You Need to Know About the 21s Bicep Curl

The 21s Bicep Curl is a intermediate difficulty exercise that targets your Biceps brachii. It's a popular choice for building strength and muscle in these areas. When should you use it? Use as a finisher or intensity technique for bicep hypertrophy. This timing makes the most of your workout and helps you get better results. Who is this for? Intermediate to advanced lifters seeking metabolic stress. Whether you're just starting out or working toward a specific goal, this exercise fits into your routine.

What muscles does the 21s Bicep Curl work?

Primary

Biceps brachii

Secondary

BrachialisBrachioradialis

Stabilizers

CoreWrist flexors

Step-by-step: 21s Bicep Curl

  1. 1

    Hold a barbell or EZ bar with underhand grip.

  2. 2

    Perform 7 reps from bottom to halfway up.

  3. 3

    Then perform 7 reps from halfway to top.

  4. 4

    Finally perform 7 full range of motion reps.

  5. 5

    Complete all 21 reps without rest.

  6. 6

    This is one set for optimal results.

What are the best tips for the 21s Bicep Curl?

Use lighter weight than normal curls.

Focus on constant tension throughout all 21 reps.

The burn will be intense - push through it.

Mistakes to watch for on the 21s Bicep Curl

Using too much weight - cant complete all 21 reps.

Loading more weight than you can control on the 21s Bicep Curl forces compensatory movement patterns that bypass your Biceps brachii. Drop the weight until you can perform every rep with clean form — your results will actually improve.

Resting between phases - reduces effectiveness.

On pulling movements like the 21s Bicep Curl, this mistake typically means your arms are doing work that should come from your Biceps brachii. Initiate every rep by engaging your Biceps brachii first, then let your arms follow.

Cheating form as fatigue sets in - maintain strict form.

On pulling movements like the 21s Bicep Curl, this mistake typically means your arms are doing work that should come from your Biceps brachii. Initiate every rep by engaging your Biceps brachii first, then let your arms follow.

Who should do the 21s Bicep Curl?

Intermediate to advanced lifters seeking metabolic stress.

How to Program the 21s Bicep Curl

StrengthNot ideal

Lower reps with heavier weight builds raw strength. Your muscles and nervous system adapt to handle more load over time. This range is best for strength-focused goals.

Muscle Growth21 reps (7-7-7)

This rep range keeps your muscles under tension long enough to trigger growth. Most people see the best muscle-building results in this zone. It balances strength and muscle size.

Endurance21+ reps

Higher reps with lighter weight builds muscular endurance and improves conditioning. This range is good for joint health and building work capacity.

General guideline: 2-3 sets of 21 reps. Rest 90-120 seconds.

What are good alternatives to the 21s Bicep Curl?

Other Variations

  • Dumbbell 21s
  • Cable 21s
  • Hammer 21s

This Exercise Is in Your Plan

MySetPlan picks the right exercises for your goals — like the 21s Bicep Curl — and builds them into a monthly program. Every set, every rep, planned out.

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Safety Notes

  • Use lighter weight.
  • Maintain form even when fatigued.