The 21s curl is a single set of three seven-rep segments done without rest: seven curls from the bottom to halfway, seven from halfway to the top, and seven full-range curls. It is a high-volume finisher that exhausts the biceps through every part of the range in under a minute.
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How effective is this exercise for you?
3
Sets
21
Reps
Barbell
Equipment
6.00
Cal/min
🎯 Muscles Worked
🎯
Primary
Biceps
➕
Secondary
Forearms
📋 How To Perform 21s Bicep Curl
1
Perform 7 curls through the bottom half range only (start to mid-point).
2
Immediately follow with 7 curls through the top half range only.
3
Finish with 7 full range-of-motion curls.
4
That's 21 total reps in one continuous set — keep elbows fixed throughout.
5
Use lighter weight than your normal curl since this is high volume.
💡 Benefits of 21s Bicep Curl
Hits the lengthened and shortened ranges of the curl in one continuous set, which creates a large pump and strong metabolic fatigue. It is also a time-saver when you want to finish the biceps quickly with a lot of volume.
📈 Sets, Reps & Programming
Use it as the last biceps exercise once per week, for 2 to 3 sets with 90 seconds of rest. Pick a barbell or EZ-bar load around 50 to 60 percent of your normal curl weight, since the final seven reps are very tiring.
⚠️ Common Mistakes to Avoid
Using a weight so heavy that the last segment is impossible
Letting the elbows swing forward as the biceps fatigue
Resting between segments, which defeats the purpose
✅ Pro Tips
Count each segment out loud so you never lose track of which seven you are on
Keep the elbows pinned to the ribs, especially during the exhausting full-range reps
🛡️ Safety Notes
Because the volume is very high for the elbow flexors, it can irritate sore elbows. Limit it to once a week and skip it if the elbows or biceps tendons are already tender.
🔁 Progressions & Regressions
Make it harderuse an EZ-bar with a slow three-second lowering phase in the full-range segment.
Make it easiercut it to 5-5-5 or use dumbbells with lighter weights.
You never let the biceps relax, so blood stays trapped in the muscle and fatigue builds across all three ranges. That is why a light weight feels heavy by the end of the set.
Is it better than normal curl sets?
It is a good finisher for variety and a pump, but heavy, progressive curls are still better for building long-term strength and size.
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