21's Bicep Curl (EZ Bar)
The 21's Bicep Curl is a high-volume bodybuilding technique using an EZ bar to target the biceps through three distinct ranges of motion. By splitting the set into partial and full repetitions, it maximizes time under tension and metabolic stress for muscle growth.
Since 21's rely heavily on time under tension and metabolic buildup, AI coaching is crucial for ensuring you don't compromise intensity as fatigue sets in. The app analyzes your RPE and rep performance to ensure the weight is light enough to complete the full 21 reps but heavy enough to stimulate growth. Additionally, if your daily recovery metrics (HRV, sleep) indicate central nervous system fatigue, the AI may suggest a standard curl variation to prevent overtraining, as this specific protocol is highly taxing on local muscle recovery.
Form Cues
- Pin your elbows firmly against your ribcage throughout the entire set.
- Stop the bar exactly parallel to the floor during the first seven partial reps.
- Squeeze the biceps hard at the top of the movement during the second phase.
- Maintain a controlled tempo; avoid dropping the weight.
- Perform all 21 repetitions consecutively without setting the bar down.
- Don't swing your torso or hips to generate momentum.
- Don't let your elbows drift forward or flare out.
- Don't rest between the three 7-rep segments.
- Don't shorten the range of motion on the final seven full reps.
Common Mistakes
- Selecting a weight that is too heavy to complete strict reps
- Resting or pausing between the 7-rep segments
- Turning the bottom partials into simple momentum swings
- Leaning back to hoist the weight up during the final reps
Muscles Worked
This exercise intensely targets the biceps brachii, hitting both the short and long heads by varying the range of motion. The semi-supinated grip on the EZ bar also engages the brachialis and forearms, while the prolonged set duration creates significant metabolic stress to drive hypertrophy.
Primary
Secondary
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