Written by Kiel DiGiovanni | Co-founder
Fact checked by Kirsten Yovino, CPT Brookbush Institute
FACT CHECKED
21s aren’t only related to the game of Blackjack. 21s, or more specifically biceps 21s, are a modified version of the biceps curl which can help you build big guns. You might be thinking “what exactly are biceps 21s?”.
In short, bicep 21s, or just "21s" for short, are biceps curl broken up into three range of motions. You’ll do seven partial reps at the bottom half, seven reps at the top half of the movement, then seven reps of the full biceps curl.
Read on to learn more about where biceps 21s came from, benefits, muscles worked, plus we’ll give you a few variations that you can use to get stronger.
WHAT ARE BICEPS 21S?
Biceps 21s is an exercise that centers around the biceps curl but breaks it down into three separate movements. Biceps 21s are comprised of 3 sets of 7 reps done without rest, with the first two sets being partial reps and the last set being full range of motion. So, in the first set, you will do partial reps of a biceps curl from starting position up to where your elbows are bent at 90 degrees. Then you will do another seven partial reps of the second half of the movement from where your elbows are bent at 90 degrees until you complete the curl. Finally, the last set of 7 reps will be the complete range of motion moving your arm through full flexion and extension. There are no rest periods between these three mini-sets. Essentially, the 3 sets are one large set of 21 reps.
WHO CREATED THE BICEPS 21S?
The answer to who created the exercise of biceps 21s isn’t so cut and dry. There are a few personalities that we should mention who may have had a hand in devising this effective arm-building exercise. Let’s start with the person who brought the most attention to the biceps 21s, Arnold Schwarzenegger 1.
Arnold swore by this bicep exercise to gain mass on his arms. In 1985 the Encyclopedia of Bodybuilding was published where Arnold spoke about the 21s. As you probably guessed, his mention of this exercise led people worldwide to start doing biceps 21s.
So, at this point, we are confident to say that Arnold popularized this exercise, but he never formally acknowledged that he was the creator.
The other people often associated with the biceps 21 exercise are Vince Gironda, Wag Bennet, and Dr. Ron Laura.
Starting with Vince Gironda, some people believe that he was the original creator of the 21s. Gironda is one of the most important figures in bodybuilding history and has a few exercises named after him, such as the Gironda pullup and Gironda dip. Some claim that Gironda came up with 21s but was called Super 21s. We didn’t find much to corroborate this, but it’s a possibility.
Next, Dr. Ron Laura is the only one to have claimed to invent the 21s. Dr. Laura is best known for his Matrix training system. He claimed that he came up with the idea of biceps 21 when he was a kid to keep up with his older brother and his friends when they lifted weights. Dr. Laura eventually created 48 Matrix Principles based on partial reps of various movements to hit the whole body. Dr. Laura ended up becoming friends with the famous Joe Weider and wrote for his publications. Weider played a large role in Arnold’s success, so this might’ve been where Arnold got the 21s from.
Lastly, we should look at Wag Bennet. Bennet met Arnold at a bodybuilding competition in London before Arnold became a worldwide phenom. Bennet ended up taking Arnold into his home and coached him to his first bodybuilding title. Although Bennet also never claimed to create the 21s, the well-known bodybuilder Lee Labrada said that Bennet taught him this exercise while he was in London.
With only Dr. Ron Laura claiming that he created the biceps 21s, we’ll go with him as the creator, although the story of the exercise isn’t as clear-cut as many others.
HOW TO DO BICEPS 21'S
Firstly, it should be noted that you can do bicep 21's with a barbell, EZ bar, a cable machine using a straight bar, dumbbells, or even resistance bands.
For the purpose of these instructions, we will be discussing the biceps 21s with a barbell or EZ bar.
- Grab a barbell or EZ curl bar with both hands shoulder-width apart using an underhand (supinated grip).
- Stand up straight with your feet hip-width apart, keeping your core engaged and back neutral.
- Start with your arms straight and tucked to your sides, then depress your shoulders down and back.
- Lift the bar while keeping your elbows tucked to your side until your elbows are bent at 90 degrees, and your forearms are parallel with the floor. Slowly lower the bar to starting position, then repeat this halfway rep a total of seven times.
- After completing seven half-biceps curls, you will move on to the second phase of the exercise without any break.
- Starting from the position with your elbows bent at 90 degrees, then curl the bar up until your arms are fully contracted, and your hands are chest level. Next, slowly lower the bar back to halfway position with your elbows at 90 degrees. Complete a total of seven repetitions.
- Lastly, start with the bar at the bottom of the movement with your arms completely straight.
- Then, perform the last seven repetitions by doing full biceps curls where you lift the bar up and down while keeping your elbows fixed at your sides.
BICEP 21S MUSCLES WORKED
The name should give it away; biceps 21s primarily work the biceps brachii and hit the brachioradialis, brachialis, and multiple smaller forearm muscles.
Let’s take a look at the major muscles worked when doing 21s and how they function.
Biceps Brachii:
The biceps brachii is found on the front of the upper arm and comprises two heads; the long head and short head. The main function of the biceps is flexion at the elbow and supination (palms facing towards you) and pronation (palms facing away) of the forearm. The long and short heads start at the scapula but at different points, then converge to cross at the elbow. If you want to build the peak of your biceps, then you should target the long head, whereas the short head adds width to the upper arm2.
Brachialis:
The brachialis is also found on the upper arm next to the biceps. The brachialis is the main driver of elbow flexion, up to 50% more powerful than the biceps when flexing at the elbow3. However, the brachialis doesn’t play any role in supination or pronation of the forearm.
Brachioradialis:
This muscle sits on the radial side of the forearm. If you raise your arm with your palm facing down, the brachioradialis is on the upper inner side of the forearm just below the elbow4. The main function of the brachioradialis is flexion of the forearm at the elbow. The brachioradialis supports pronation and supination of the forearm. The brachioradialis also provides stability to the elbow when it’s being flexed and extended in a dynamic movement.
BENEFITS OF BICEPS 21S
Biceps 21s are an awesome exercise to help build up the biceps peak, and there are a few good reasons why this exercise was one of Arnold’s favorites.
Here’s a glance at some of the benefits of doing biceps 21s:
1. Increased Time Under Tension:
Biceps 21s help increase the time your muscles are contracted while performing the biceps curls. By doing biceps 21s, you can overload the muscles in the arms, which can lead to both myofibrillar and sarcoplasmic growth. In addition, you’ll get an amazing pump when doing 21s properly because you’re completing 21 reps while doing both partial reps in the top and bottom range plus the full ROM.
2. Bigger Biceps:
Some of the greatest bodybuilders of all time, including Arnold Schwarzenegger, used biceps 21s to help build big, defined arms. The increased volume of doing this exercise can lead to more potential gains in mass and size.
3. Enhanced Grip Strength:
When performing biceps 21s, you’re forced to hold the bar for a longer time than most exercises which aids in building better grip strength. The second portion of the biceps 21s is especially taxing on the grip as you have to decelerate the weight the bring it to a complete stop while your elbows are flexed at 90 degrees.
BICEPS 21 TIPS & TRICKS
1. Don’t Rock:
Lift the weights in a controlled motion throughout the exercise. We will often see people attempting to do 21s by rocking their body or using leg drive to help swing the weight upwards. However, if you’re using momentum to help curl the weight, then you may be trying to lift weights that are too heavy.
How to Fix: You can try to do biceps 21s while seated if you’re using dumbbells so that it’s harder to create momentum to lift the weight. You can also try preacher curl 21s to eliminate any movement at the elbow.
2. Choose Correct Weight:
With this exercise, you’re performing 21 repetitions without a break, so the weight or resistance you’re using shouldn’t be extremely heavy. Usually, when lifting for hypertrophy, you’ll be in a rep range of 6-12, so you’ll need to lower the amount of weight you’re using compared with doing a regular set of biceps curls.
How to Fix: Start with a moderate to light weight for your first set to gauge how heavy you can go without negatively affecting your form.
3. Switch Up Equipment:
Your body will adapt and get used to the same training stimuli over time, so it’s important to keep shocking the muscles. You can shock the muscles in several ways, including changing equipment used, sets and reps, training methods, grip, and body positioning.
How to Fix: Try doing biceps 21s with different equipment such as dumbbells, kettlebells, resistance bands, or the cable machine. Change up body positioning as well from standing or seated to a prone position.
4. Take Your Time:
Biceps 21s will yield the best results when completing them in a slow controlled motion. Many people will start swinging the weights up and down to get the exercise completed as fast as possible because it’s a hard exercise that will make those biceps burn.
How to Fix: Focus on the contraction of the muscles in each rep. When lowering the weight, try using a longer eccentric phase for 1-3 seconds.
5. Change Up Weights:
Each phase of the biceps 21 puts different stress on the muscles. The first portion of the lift from starting to mid-way is easy, and the second half is easy to complete.
The halfway point is where most people get stuck, as this is the part of the most difficult motion to complete. Adapt to the strength curve by changing the weights you’re lifting.
How to Fix: Try to use three different weights to complete biceps 21s. For example, use 25lb dumbbells for the first seven reps. Then try doing the next seven partial top-end reps with 30lb dumbbells. Lastly, drop it down to using 20lb dumbbells for the final seven reps of the full range of motion which are the hardest reps to complete.
6. Alternate Rep Range:
The exercise is named biceps 21s because you’re doing 21 total reps. However, you can change the rep ranges and still be within the scope of possible hypertrophy. Some studies show that hypertrophy still takes place with rep ranges up to 40.
How to Fix: Try switching up the normal seven rep range for each phase of the 21s and go lower or higher. You can do 5, 5, 5, or even 10, 10, 10. Shocking the muscles is one way you can stimulate muscle growth.
7. Use Different Body Positioning:
The original biceps 21s closely mimics the standing biceps curl. Your body and muscles might be used to doing biceps curls which could hamper muscle growth.
How to Fix: You can try doing biceps 21s on an incline bench, either lying face-first or on your back. You could also set up a bench under the cable machine then lie down underneath it while reaching up to grab the bar. Then perform the 21s while pulling the bar down towards your head.
8. Switch Grips:
Many people tend to always use the same grip width when performing curls. However, it’s important to vary the width and type of grip you use to hit all regions of the biceps and arms in general.
How to Fix: Try using a narrow grip to hit the inner biceps, then change it up to a wide grip to hit the outer biceps. You can also play around with grips, such as the overhand or reverse curl and the neutral grip or hammer curl.
8 BEST VARIATIONS OF BICEPS 21S
You can execute biceps 21s with a variety of equipment, but the form will stay the same. For example, you can use dumbbells, resistance bands, or a cable machine.
1. DUMBBELL 21s
Using dumbbells to do biceps 21s can give you slightly more motion range than a straight bar. You can also do 21s with one arm at a time if you have one side weaker than the other. In addition, unilateral exercises allow you to spot weaknesses or muscle imbalances. Dumbbells will also require a tad more stabilization compared with using a barbell or EZ curl bar.
2. BAND 21s & CABLE 21s
Resistance bands and the cable machine are great for doing biceps 21s. One of the best aspects of using these tools for 21s is applying constant tension on the muscles. You’re sure to feel a serious burn when using these tools with 21s.
3. HAMMER CURL 21s
Hammer curl 21s are an excellent variation of the traditional 21 as they hit the biceps differently. With hammer 21s, you’ll target the long head of the biceps more than you would with a regular biceps curl due to the hand position and the need to use the neutral grip. Follow the same cues as the biceps 21s except for the grip. You can do hammer 21s with dumbbells, resistance bands, or the rope attachment on a cable machine.
4. REVERSE GRIP CURL 21s
Reverse curl 21s can be an awesome exercise to work the arms while placing less stress on the elbows. When doing reverse curls 21s, you simply will hold the tool of your choice with a pronated grip with your palms facing towards you at starting position. With reverse 21s, you’ll place more emphasis on the brachialis and the brachioradialis while taking some stress off your biceps. You can perform reverse 21s with all the same equipment that you could use for the traditional biceps 21s.
5. PREACHER CURLS 21s
If you want to turn it up a notch with the biceps 21s, you should try to do them in conjunction with a preacher curl bench. By doing 21s on the preacher bench, you’ll have strict isolation of the muscles as your elbows will be fixed in place, allowing no room for cheating by using the body’s momentum. Also, you might want to start with weights that are a little lighter with this one because it will be more difficult to curl the weight up.
6. PULL UPS 21s
The pullup is one of the best upper body exercises that you can do. Although pullups primarily target the lats, the biceps are also engaged to get the exercise done. This will be a challenging take on an already difficult exercise. To do pullups 21s:
- Complete the first seven reps as you pull yourself up until your elbows are bent at 90 degrees.
- Then, do seven more reps from the 90-degree elbow position until your chin reaches the bar.
- Finally, finish off with seven reps of the full range of motion of a pullup.
Note: If unassisted pullups are too difficult, you can do this same exercise with resistance bands, a pullup assistance machine, or even on the lat pull down.
Related: Pull Ups vs Chin Ups
7. CONCENTRATION CURLS 21s
Concentration curls 21s are a perfect solution to make sure you get the most out of the biceps. To do concentration curls 21s, you need a bench and a dumbbell. First, simply sit on the edge of a bench, then grab a dumbbell with an underhand grip. Next, lean forward, then place your active arm’s elbow against your inner thigh. Finally, perform the three ranges of motion from this position.
8. DRAG CURL 21s
Drag curls have a shorter range of motion compared with a traditional biceps curl. However, drag curls are a great biceps exercise to put on mass as they emphasize the biceps and take some stress off the elbows and deltoids. To do drag curls 21s, you’ll be in the same position as biceps 21s. The difference here is that you’ll be dragging the bar up your torso, so as you lift the weight, your elbows will go up and back. Try to complete seven reps at the bottom half, top half, and a full range of motion.
Note: If you already have massive arms, this exercise might be difficult to break into three ranges of motion.
How Many Sets of Biceps 21s Should I Do?
You can treat bicep 21s like you would any other exercise. Do 3-4 sets mixed in with your other bicep exercises. You can also make the bicep 21s your only bicep exercise for a workout and do 5+ sets. In the end, you should try to exhaust your biceps, so however many sets it takes.
At some point, though, rather than doing endless sets, increasing the weight load is best (as long as you can complete the reps with good form). So, generally speaking, we'd say no more than 6-8 sets for a workout, with consideration of aiming for 10-15 total sets for the biceps per week.
FINAL NOTE:
Biceps 21s are a fantastic exercise to grow some solid arms. You can apply this same training technique to other exercises to reap the same benefits of overloading the muscles through added time under tension and various rep ranges which leads to a massive pump. You can apply the 21s training method to other exercises as well, get creative. Remember that it’s important to keep your workouts fresh, so next time you’re in a rut or want to finish your workout with an intense exercise, give biceps 21s a shot.
More Biceps Exercise Resources:
- 8 Best Long Head Biceps Exercises
- 9 Best Short Head Biceps Exercises
- 12 Best Dumbbell Biceps Exercises
- Average Biceps Size | Building 15-19 Inch Arms
References:
- The History of 21s - Physical Culture Study. physicalculturestudy.com. Published May 14, 2018. Accessed October 17, 2023. https://physicalculturestudy.com/2018/05/14/the-history-of-21s/
- Jarrett CD, Weir DM, Stuffmann ES, Jain S, Miller MC, Schmidt CC. Anatomic and biomechanical analysis of the short and long head components of the distal biceps tendon. Journal of Shoulder and Elbow Surgery. 2012;21(7):942-948. doi:https://doi.org/10.1016/j.jse.2011.04.030
- Brachialis muscle. Wikipedia. Published January 13, 2023. https://en.wikipedia.org/wiki/Brachialis_muscle
- Caufriez B, Dugailly PM, Brassinne E, Schuind F. The Role of the Muscle Brachioradialis in Elbow Flexion: An Electromyographic Study. The Journal of Hand Surgery (Asian-Pacific Volume). 2018;23(01):102-110. doi:https://doi.org/10.1142/s2424835518500145
Kiel DiGiovanni
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