Biceps 21s: Technique, Benefits, and Safety Tips

How to do biceps 21?

Biceps 21s are an advanced resistance training technique that involves performing 21 repetitions of a biceps curl, broken down into three distinct phases of 7 repetitions each, targeting different ranges of motion to maximize time under tension and muscle fatigue.

What Are Biceps 21s?

Biceps 21s, often referred to simply as "21s," are a specialized intensity technique designed to challenge the biceps brachii muscle through its full range of motion, but with a unique rep scheme. Instead of performing 21 continuous repetitions, the exercise is divided into three distinct sets of 7 repetitions, performed consecutively without rest:

• Phase 1 (7 reps): Bottom half of the curl (from full extension to approximately 90 degrees of elbow flexion).
• Phase 2 (7 reps): Top half of the curl (from approximately 90 degrees of elbow flexion to full contraction).
• Phase 3 (7 reps): Full range of motion curls (from full extension to full contraction).

This methodology aims to increase time under tension (TUT), enhance metabolic stress within the muscle, and potentially stimulate new growth by thoroughly fatiguing the muscle fibers.

Anatomy & Biomechanics: Why 21s Target the Biceps

The biceps brachii is a two-headed muscle located on the front of the upper arm, primarily responsible for elbow flexion (bending the arm) and forearm supination (rotating the palm upwards). It also assists in shoulder flexion.

The effectiveness of Biceps 21s lies in their manipulation of the strength curve and muscle recruitment patterns:

• Bottom Half (0-90 degrees): This initial phase often represents the weakest point of the biceps curl for many individuals, as the muscle is in a more lengthened position and mechanical advantage is lower. Focusing on this range helps to strengthen the biceps from its stretched position, improving force production at the start of the movement.
• Top Half (90-180 degrees): As the elbow flexes beyond 90 degrees, the biceps gains a better mechanical advantage, making the top portion of the curl feel "stronger" for some, but also requiring significant contraction to achieve peak shortening. This phase emphasizes the peak contraction and full shortening of the muscle fibers.
• Full Range of Motion: Combining both partial ranges ensures that the entire muscle is worked through its complete physiological range, integrating the strength gains from the partial repetitions and driving maximum blood flow and metabolic stress.

By hitting these different ranges consecutively, Biceps 21s ensure a comprehensive stimulus, addressing potential sticking points and maximizing the recruitment of muscle fibers throughout the entire movement arc. The prolonged time under tension and minimal rest between phases lead to significant metabolic accumulation (e.g., lactate), which is a powerful signal for muscle adaptation and hypertrophy.

Step-by-Step Guide: Performing Biceps 21s Correctly

While Biceps 21s can be performed with various equipment, the barbell or EZ curl bar is most common. Choose a weight that allows you to maintain strict form, especially during the later phases. You will likely need to use a lighter weight than you would for a standard set of 7-10 repetitions.

Equipment: Barbell, EZ curl bar, or dumbbells.

Starting Position:

• Stand tall with your feet shoulder-width apart, knees slightly bent, and core engaged.
• Hold the bar with an underhand grip (palms facing up), hands roughly shoulder-width apart. If using dumbbells, hold one in each hand with palms facing forward.
• Arms should be fully extended downwards, close to your body. Shoulders should be pulled back and down, not rounded forward.

Phase 1: Bottom Half (7 Reps)

1. Execution: From the starting position, slowly curl the weight upwards, stopping when your forearms are roughly parallel to the floor (elbows at about 90 degrees). Do not raise the weight any higher.
2. Focus: Concentrate on feeling the biceps contract through the initial range of motion. Maintain control; do not swing the weight.
3. Return: Slowly lower the weight back down to the starting position, ensuring full extension of the arms at the bottom.
4. Repetition: Complete 7 repetitions of this bottom-half movement. Do not rest after the 7th rep; immediately transition to Phase 2.

Phase 2: Top Half (7 Reps)

1. Execution: Without lowering the weight fully, start with the weight at the mid-point (forearms parallel to the floor, elbows at 90 degrees). From here, curl the weight upwards towards your shoulders, achieving a full biceps contraction.
2. Focus: Squeeze your biceps hard at the top of the movement. Your elbows should remain relatively fixed by your sides; avoid letting them drift forward excessively.
3. Return: Slowly lower the weight back down only to the mid-point (forearms parallel to the floor). Do not lower it past this point.
4. Repetition: Complete 7 repetitions of this top-half movement. Do not rest after the 7th rep; immediately transition to Phase 3.

Phase 3: Full Range of Motion (7 Reps)

1. Execution: From the starting position (arms fully extended), curl the weight all the way up to your shoulders, achieving a full biceps contraction.
2. Focus: Emphasize a smooth, controlled movement throughout the entire range. Avoid using momentum or swinging your body.
3. Return: Slowly lower the weight back down to the starting position, ensuring full extension of the arms at the bottom.
4. Repetition: Complete 7 repetitions of this full-range movement.

Breathing: Inhale as you lower the weight (eccentric phase) and exhale as you curl the weight upwards (concentric phase).

Tempo: Aim for a controlled tempo, perhaps a 2-0-2-0 count (2 seconds up, 0 pause, 2 seconds down, 0 pause) for the full range, and similar control for the partials.

Benefits of Incorporating Biceps 21s

• Increased Time Under Tension (TUT): By performing 21 repetitions with minimal rest, the biceps muscle is under constant tension for an extended period, which is a primary driver of muscle hypertrophy.
• Enhanced Metabolic Stress: The continuous nature of the exercise leads to a significant build-up of metabolic byproducts (e.g., lactate, hydrogen ions), creating a "pump" sensation and signaling adaptations for muscle growth and endurance.
• Improved Mind-Muscle Connection: The focus on distinct ranges of motion encourages greater awareness and control over the biceps contraction, helping individuals to better "feel" the muscle working.
• Breaking Through Plateaus: For those struggling to add size or strength to their biceps, 21s can provide a novel stimulus that shocks the muscle into new growth.
• Versatility: This technique can be applied to various biceps curl variations (e.g., dumbbell curls, preacher curls, cable curls), offering flexibility in training.

Important Considerations & Safety Tips

• Weight Selection is Crucial: Do not ego-lift. Use a lighter weight than you think you need. The goal is muscle fatigue through controlled movement, not lifting heavy with poor form. If you cannot complete all 21 reps with good form, the weight is too heavy.
• Form Over Weight: Strict form is paramount. Avoid swinging your body, using your lower back, or shrugging your shoulders to lift the weight. These actions shift tension away from the biceps and increase the risk of injury.
• Avoid Momentum: The effectiveness of 21s comes from constant tension. Using momentum negates this principle.
• Listen to Your Body: While muscle fatigue is the goal, pain (especially in the elbows or wrists) is a warning sign. Stop if you experience sharp or unusual pain.
• Frequency: Biceps 21s are an intense technique. They should not be performed every biceps workout. Incorporate them strategically, perhaps once every 1-2 weeks, to avoid overtraining or excessive joint stress.
• Warm-up: Always perform a thorough warm-up before attempting 21s, including light cardio and dynamic stretches for the arms and shoulders.

Variations and Alternatives

The 21s principle can be adapted to other biceps exercises:

• Dumbbell Biceps 21s: Perform the same 7-7-7 rep scheme using dumbbells. This allows for independent arm work and can help address muscular imbalances.
• Preacher Curl 21s: The preacher curl machine or bench isolates the biceps further by fixing the upper arm. This can make the 21s even more intense and challenging to maintain strict form.
• Cable Curl 21s: Using a cable machine provides constant tension throughout the entire range of motion, which can be particularly effective for 21s.

While 21s are a specific application of partial repetitions, other intensity techniques like drop sets, supersets, and rest-pause sets also serve to increase training volume and intensity.

Who Should (and Shouldn't) Do Biceps 21s?

Should Do:

• Experienced Lifters: Individuals with a solid foundation in resistance training and good understanding of proper form.
• Those Seeking Hypertrophy: Athletes and enthusiasts whose primary goal is muscle growth and who want to add an advanced intensity technique to their routine.
• Individuals Breaking Plateaus: Those who feel their biceps growth has stagnated and need a new stimulus.

Shouldn't Do (or Exercise Caution):

• Beginners: Novice lifters should first master basic biceps curl mechanics with full range of motion before attempting advanced techniques.
• Individuals with Joint Issues: Those with pre-existing elbow, wrist, or shoulder pain may find the prolonged tension and specific ranges of motion exacerbate their condition. Consult a healthcare professional or physical therapist.
• Those Prioritizing Absolute Strength: While 21s can contribute to strength, their primary benefit is hypertrophy and muscular endurance, not maximal strength.

Conclusion

Biceps 21s are a highly effective, advanced training technique for stimulating biceps growth and enhancing muscular endurance. By strategically segmenting the biceps curl into three distinct ranges of motion, they maximize time under tension and metabolic stress, offering a powerful stimulus for hypertrophy. However, their intensity demands strict adherence to proper form, appropriate weight selection, and careful integration into a well-structured training program. When executed correctly and safely, Biceps 21s can be a valuable tool in any serious fitness enthusiast's arsenal for building stronger, more developed arms.