Dumbbell 21s

Muscles worked

Setup

1. Stand with your feet shoulder-width apart and a dumbbell in each hand.
2. Hold the weights with a supinated grip (palms facing forward).
3. Pull your shoulder blades back and down, pinning your elbows firmly against your ribcage.
4. Maintain a slight bend in your knees to stabilize your lower body.

How to do it

1. Phase 1: Perform 7 partial repetitions from the bottom (full extension) up to the halfway point (90-degree elbow flexion).
2. Phase 2: Immediately perform 7 partial repetitions from the halfway point (90 degrees) up to the top of the curl near your shoulders.
3. Phase 3: Finish with 7 full-range repetitions, moving from complete extension all the way to the top.
4. Exhale forcefully on every upward curl and inhale as you control the weight back down.

Form checklist

• Keep your elbows locked in place; do not let them swing forward or flare out.
• Avoid using momentum or leaning back to lift the weights.
• Maintain a neutral wrist position to keep the tension on the biceps rather than the forearms.
• Ensure the transition between the three phases is seamless with no rest in between.

Pro tips

• Squeeze the dumbbells as hard as possible to increase neural drive and muscle fiber recruitment.
• Focus on a 2-second eccentric (lowering) phase during the final 7 full reps to maximize muscle damage.
• Keep your chest up and core braced to prevent the shoulders from taking over the movement.

Make it harder

• Perform the exercise seated on an incline bench to increase the stretch on the long head of the biceps.
• Add a 1-second pause at the peak of the contraction for the final 7 full-range repetitions.

Frequently asked

What muscles does the dumbbell 21s work?

The dumbbell 21s primarily targets the biceps, and also works the deltoids and triceps as secondary muscles.

What equipment do you need for the dumbbell 21s?

The dumbbell 21s uses dumbbell.

Is the dumbbell 21s good for beginners?

The dumbbell 21s is rated intermediate. Build a base with simpler variations first, then progress to it with light load and strict form.

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