Step by step instructions, muscle activation and variants for the Dumbbell 21s.
Dumbbell 21s is an advanced bicep curl variation that divides a full curl into three seven-rep segments — lower half, upper half, and full range — performed back-to-back for a total of 21 reps. This technique floods the biceps with constant tension across the entire range of motion.
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The Dumbbell 21s is a foundational movement that builds strength and muscle through controlled, progressive overload. Train it 1 to 2 times per week with 3 to 5 working sets per session, gradually adding weight or reps as form holds up.