Swinging the torso
Keep the ribs over the pelvis and reduce the load if the curl needs a hip drive or backward lean.
21s Curls
21s Curls trains the biceps and supporting elbow flexors through a controlled elbow-flexion path while the upper arm remains stable.
- Primary muscle
- Biceps
Primary musclesBiceps brachii
Secondary musclesBrachialis, Brachioradialis, Forearm flexors
- Equipment
- Barbell
How to perform 21s Curls
Follow the sequence in order, paying attention to the starting position, movement path, and finish described in each step.
Stand tall holding a straight bar with an underhand grip, upper arms close to the sides, and the elbows fully extended under control.
Brace the trunk, keep the wrists straight, and use a resistance that allows all 21 repetitions without swinging.
Perform seven curls from the bottom to roughly 90 degrees of elbow bend, returning only to the bottom after each repetition.
Continue with seven repetitions from roughly 90 degrees to the top of the curl, returning only to the halfway point.
Finish with seven full-range curls from straight arms to the top; keep the torso still through all 21 repetitions.
Common 21s Curls mistakes
Elbows travelling forward
Keep the upper arms close to the torso or pad instead of turning the top into a shoulder raise.
Wrists bending
Hold the wrists straight so the forearms transfer force without unnecessary joint strain.
Dropping the weight
Lower the weight for two to three seconds instead of letting it pull the hands down.
When to modify or choose another exercise
- Swinging the torso: Keep the ribs over the pelvis and reduce the load if the curl needs a hip drive or backward lean.
- Wrists bending: Hold the wrists straight so the forearms transfer force without unnecessary joint strain.
- Stop when the exercise produces sharp, catching, radiating, or increasing joint pain rather than the expected muscular effort.
- Alternative Supported dumbbell curl: Sit or use a preacher pad to reduce trunk momentum and keep the upper arm still.
How to use 21s Curls in a training program
Where it fits in a session
Place 21s Curls after rows, pulldowns, and pull-ups so biceps and grip fatigue do not limit compound pulling.
How often to use it
Use one to three times per week and count pulling sets that already train the elbow flexors.
Starting rep ranges by goal
| Goal | Sets | Reps or time | Rest | Effort and execution |
|---|---|---|---|---|
| Technique | 2–3 | 1 sequence (21 reps) | 90–150 sec | Light enough to keep every partial range distinct |
| Muscle growth | 2–4 | 1 sequence (21 reps) | 90–180 sec | Stop if swinging or elbow drift begins |
Pairing and sequencing
- Use 21s Curls after Barbell Bent Over Rows or Wide-Grip Lat Pulldowns.
- Pair it with Straight Bar Tricep Extension for an opposing arm superset.
Scale the movement
Regressions and progressions for 21s Curls
Start with an easier option
Supported dumbbell curl
Sit or use a preacher pad to reduce trunk momentum and keep the upper arm still.
Light straight-bar curl
Use a light straight bar through full-range curls to practise a steady elbow path before using the 21-repetition sequence.
Progress when form is repeatable
Slow-Lowering 21s Curls
Lower for three to four seconds while keeping the wrists straight.
Single-Arm Curl
Train one arm at a time to compare control between sides.
References
- Mayo ClinicBiceps Curl with Dumbbell ↗
- Mayo ClinicWeight Training: Do's and Don'ts of Proper Technique ↗
- American College of Sports MedicineACSM Resistance Training Guidelines Update ↗
Dumbbells
Dumbbell Bicep Curl To Shoulder Press
Dumbbells
Dumbbell One Arm Preacher Curl
EZ Curl Bar
EZ Bar Standing Curls
Dumbbells
Preacher Single-Arm Hammer Dumbbell Curl
Dumbbells
Seated Alternate Dumbbell Biceps Curls
Strength Machine
Seated Bicep Curl Machine
Dumbbells
Standing Alternate Dumbbell Biceps Curls
Dumbbells
Standing Alternate Hammer Curl
Barbell
Standing Barbell Curls
Strength Machine
Standing Cable Rope Hammer Curl
Strength Machine
Standing Cable Single-Arm Curl
Dumbbells
Standing Dumbbell Biceps Curls
Dumbbells
Standing Hammer Curl
Barbell
Standing Reverse Barbell Curls
Barbell
Barbell Biceps Curl
EZ Curl Bar
EZ-Bar Preacher Curl
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