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Barbell 21s Bicep Curl
Barbell curl variation dividing 21 reps into bottom-half, top-half, and full-range phases to target biceps for hypertrophy and endurance through increased time under tension.
About Exercise
Equipment
Barbell
Difficulty
3/5 • Intermediate
Primary Muscle Groups
Biceps
Secondary Muscles
Shoulders
Popularity Score
7
Goals
Training Style
Setup Requirements
Requires Rack
No
Requires Bench
No
Requires Spotter
No
Space Needed
Small
Noise Level
Low
Muscle Breakdown
View Muscle MapBiceps
10/10Long Head, Short Head, Brachialis
Forearms
6/10Flexors
Shoulders
3/10Anterior Delts
Programming
Typical Rep Range
21-21 reps
Rest Between Sets
60-120 seconds • Recover fully between sets
How to Perform
Stand with feet shoulder-width apart, knees slightly bent, gripping barbell underhand at shoulder width with arms extended and bar resting on thighs.
- Curl bar from thighs to forearms parallel to floor for 7 bottom-half reps, controlling descent each time.
- Without rest, curl from parallel forearms to full contraction near chest for 7 top-half reps, lowering to parallel each time.
- Without rest, perform 7 full-range curls from thighs to chest, squeezing biceps at top and controlling eccentric.
- Keep elbows tucked to sides throughout all phases.
- Engage core to maintain upright posture.
- Avoid swinging body or using momentum.
Coaching Tips
Form Cues
- Elbows pinned to ribs
- Squeeze biceps hard at top
- Control every inch
- No body swing
- Neutral wrists
Breathing
Exhale during concentric lift and inhale during eccentric lower; brace core throughout.
Tempo
2-0-1
Range of Motion
Bottom: arms extended to 90-degree elbow flexion; top: 90-degree to full flexion with bar near shoulders; full: complete extension to full flexion.
Safety
Safety Notes
- Avoid if acute elbow pain present
- Use lighter weight to maintain form through fatigue
- Keep back straight to protect spine
- Control descent to reduce elbow stress
- Select weight allowing all 21 reps with strict form
Spotting
Spotting not typically needed; partner can assist rack if heavy, but focus on form over max load.
Common Mistakes
- Swinging torso for momentum
- Flaring elbows outward
- Dropping weight on eccentric
- Rounding lower back
- Gripping too wide or narrow
When to Avoid
- Acute elbow tendonitis
- Shoulder impingement
- Wrist instability
Flexibility Needed
- Full elbow flexion
- Neutral wrist mobility
- Shoulder flexion to 90 degrees
Build Up First
- Master basic barbell curl form
- Understand partial rep technique
- Core bracing competency
Also known as
21s Bicep Curl, Barbell Twenty-Ones Curl, Partial Rep Bicep 21s
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