The 21s Workout Method Can Incite Ridiculous Muscle Growth

Triple the fun for the price of one.

You want a more intense workout, but you don’t necessarily want to load more weight onto the bar. Or you’re pressed for time and can’t afford to add even more sets to up your training stimulus and volume. If you’re looking for muscle growth, search no further than 21s.

The 21s workout method is a painfully effective modification for many of your favorite exercises. You’ll move through various ranges of motion for a total of 21 reps per set to bring any lagging muscles back to life — or to give yourself a brutal finisher to leave the gym with the ultimate pump.

A shirtless person looks at their biceps as they perform an EZ-bar biceps curl.
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With this method, you’ll incorporate both partial and full range of motion into your lifts, kicking open the door to a fresh strategy to produce muscle growth. Add this to your options to serve your training needs and goals beyond the simple — and admittedly, sometimes boring — three sets of 10 straight-set approach. Here’s how to supercharge your results with the 21s workout method.

21s Workout Method Explained

21s (sometimes called sevens) involves breaking up one exercise into three distinct ranges of motion for a single 21-repetition set. You would complete a set of 21s as follows:

  • Perform seven repetitions in the bottom part of the range of motion.
  • Perform seven repetitions in the top part of the range of motion.
  • Perform seven repetitions using the complete range of motion.
  • Rest (you’ll need it).

Given the amount of volume and intensity generated from a single set of 21s, consider performing these sets as a finisher for a particular muscle group.

What the Science Says

Research on hypertrophy training — the art of building muscle — has shown that the vast majority of gains can be achieved across a wide range of repetition and loading strategies. (1) There’s no one way to gain muscle, and attacking a muscle group in various ranges of motion produces a range of benefits. (2

Growing Muscle

A major key to stimulating muscle growth is generating mechanical tension. (3) There are certain signs to look for that an exercise has reached the point of being challenging enough to produce the mechanical tension needed to cause growth. 

One of the most reliable signs that a muscle is generating a high degree of mechanical tension is an involuntary slowing of the concentric portion of the exercise. When the repetitions start to slow down, muscle failure usually isn’t far behind. Achieving this same end-of-set tension (or proximity to muscle failure) is what gives you the potential to gain similar amounts of muscle with higher and more moderately loaded exercises. (1

A person wearing a sports bra and pink shorts performs a lat pulldown facing away from the camera.
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In the case of 21s, the increased number of repetitions within a single set is a key to generating enough mechanical tension. As opposed to something more conventional like heavier sets of six to 12 reps, the 21s workout method forces the same muscle to perform 21 repetitions before resting. As long as you select a load that would cause you to be close to muscle failure by the end of those 21 repetitions, you’re all set.

Range of Motion

The other side of the equation is digging into the concept of partial range of motion that 21s will employ. Although in the totality of training, you’ll usually want to move through a full range of motion for muscle growth and other benefits to your movement patterns. But partials — reps focusing on the top or bottom end of a range of motion — can also be worthwhile. 

Research has shown that training through a partial range of motion is quite capable of producing muscular growth. (3) Certain muscle groups may experience unique challenges from training different lengths and ranges of motion, making certain exercises — discussed below — excellent choices for 21s training. (3)(4)

Common Exercises for 21s

The 21s workout method is particularly useful for exercises that encompass long ranges of motion. Something like biceps curls or leg extensions are great examples, because you’ll maximize your movement with moves that let you really flex.

Biceps Curls

Choose an EZ-bar curl or preacher curl — either the machine or free weight version — for training 21s with your biceps.

Both allow for a long range of motion and the ability to safely struggle during the last few full-length repetitions. 

Leg Extensions

The leg extension is a perfect choice for 21s quadriceps training since you can very rapidly adjust the pin-loaded resistance to accommodate each range of motion as necessary.

This will help you achieve a fully-stimulating challenge by the end of the set. 

Lateral Raise

Dumbbell or behind-the-back bilateral cable lateral raises are two fantastic options to roast your delts. Since unilateral work calls for a ton of stability and impart huge amounts of fatigue, choosing a bilateral variation is the way to go here.

In this case, you want to focus as much as possible on your range of motion, not leaking any extra effort into keeping yourself stable.

Prone Hamstring Curl

The prone hamstring curl is another fantastic choice for 21s training with your legs.

You can accommodate the long, sweeping range of motion with rapid changes in pin-loaded resistance — similar to the leg extension — as you begin to fatigue.

Straight-Arm Pulldown

Deploy straight-arm pulldowns for your lats. Grab a pair of long-length grips or rope attachments to use individually in each hand.

Really control the eccentric to maintain as much tension on the muscle as possible.

Landmine Hinges

Using a landmine is the easiest way to challenge yourself with a hinge variation of the 21s workout method. You can safely roast the full length of your posterior chain, taking advantage of the increased stability that a landmine can offer you as fatigue accumulates.

Perform partial range of motion landmine Romanian deadlifts at both the bottom and top before seven complete range of motion repetitions to cap the set.

Benefits of 21s

The 21s workout method provides a ton of diverse benefits to your training. The most obvious is muscle growth. However, you can also get away with using less load and building concurrent muscle endurance. It’s also an extremely straight-forward technique to employ.

Less Load

There are two major ways to stimulate a muscle to grow. Generating mechanical tension using more load or by increasing volume. Increased volume (sets or repetitions) with less rest can help you generate a similar level of mechanical tension as absolute load – without needing to rely on going heavy all the time.

Using less load is particularly useful for many exercises that target smaller muscle groups prone to technique breakdown from heavy weights. Lateral raises, biceps curls, or even hamstring curls can be overly reliant on momentum when too much weight is used – the 21s method is the perfect solution here.

Muscle Gain

The obvious benefit of 21s is making some serious gains. Smoking your muscles with a concentrated blast of volume is sure to provide some much-needed stimulus. So long as you choose the right weight and hit some peak intensity, you’re sure to incite ridiculous growth.

Muscle Endurance

Choosing certain load and repetition schemes can help emphasize building muscle, strength, or endurance. The best part about training for muscle growth is that you can grow concurrently with building both strength and endurance — depending on your training style. 

A person wearing a black tank top performs a unilateral cable preacher curl.
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The 21s method is a perfect choice to build muscle and also localized muscular endurance due to the high repetition count. Persevere through the burn and you’ll see some new, more durable gains in no time. Just make sure you’re reaching failure during your sets.

Easy to Execute

The best part about 21s is that they are simple to execute. Instead of needing to worry about several different pieces of equipment across your workout, grab one and go to town. Training in each range of motion and intensifying your set with a ridiculous repetition count takes a ton of thinking out of the process of building muscle.

Who Should Use 21s

The 21s workout method is something that a wide variety of lifters can benefit from. If you’re a beginner, bodybuilder, or even strength athlete, give it a shot.


Beginners are often in the market for building as much muscle as they can. But if you’re new at this, you might still be developing the ability to use heavy loads or more advanced exercises. Employing 21s might be just the solution you’re looking for.

It’s accessible, easily performed with beginner-level lifts, and you don’t have to go heavy to get big results. Get to packing on your much desired muscle while also working on strength or skill in other ways. 


Bodybuilders might be the most obvious group of lifters who would benefit from using the 21s workout method. If you’re looking to throw some serious volume at a muscle group and walk away with a viscous pump, 21s have got you covered. Be diligent not to over indulge here. Too much of a good thing could quickly turn into a bit too much soreness

Strength Athletes

Strength athletes may seem a bit out of place with a muscle-building strategy, but there aren’t many downsides to growing more muscle. Spending some time giving your joints some much needed TLC from high-intensity compound training might not be a bad idea. Given how infrequently strength athletes access the higher repetition ranges during training, you might get the biggest bang for your buck out of all the lifters here.

How to Program 21s

Deploy a method like 21s strategically. Like all training styles, there is a point of diminishing returns. Using it in one-off fashion when you’re strapped for time, as an intense finisher, or periodized into a grander program are great ways to maximize its effectiveness.

Strapped for Time

If you’ve only got so much time to get a great workout, lining up a series of 21s might be the best option. Using two to three sets of the 21s workout method on a few exercises could be a highly time effective way to blast through an uncharacteristically short workout. Instead of planning for a few exercises per muscle group, plan on a few excruciating sets.


The beauty of the 21s workout method is that it can be part of nearly any workout as a brutal finisher. The accumulation of repetitions over the course of the set acts to intensify your effort in rapid fashion. This helps you reach true muscular failure in short order. Knock out a round of 21s to finish off your arms to test this theory.


One of the smartest ways to employ something like the 21s workout method is to strategically weave it into a periodized training program. Most programs will employ greater levels of volume, intensity, or both over time.

One way you can cap a periodized program is by employing 21s as a finisher deep into the latter weeks of your program. This way, it can serve as one last ditch effort to maximize your results before transitioning to a new routine.

Get to Growing

If you’ve ever wanted to know what it’s like to put an inch on your arms in one workout – try the 21s workout method. The pump you experience after a good round of 21s will make you feel like you’ve gained an inch of muscle in about five minutes. This incredibly versatile and easy to perform training method can be what reignites the intensity of your program – unlocking your stagnant growth along with it. Throw some 21s into your next workout, once you try it you’ll definitely be hooked.


Still got questions about 21s? We’ve got answers.

How often should I use the 21s workout method?

The 21s workout method is something that is best used sparingly as a finisher or strategically to cap an entire training program. Your body will adapt to how you train eventually, so even intensifiers like 21s will slowly experience diminishing returns. Weave them into your program for a few sessions every two to three months to keep them as effective as possible.

What exercises should I avoid for the 21s workout method?

Exercises that require a lot of technique, bracing, or are heavily loaded should be avoided with this method. The key to a good set of 21s is not having to stop during the set. Certain implements like barbells are harder to employ 21s with because your ability to brace or control the barbell may limit your ability to take your desired muscle to failure. If your core gives out before your arms or legs, you might end up spinning your tires and even risking injury.

How long should I rest?

You want to complete all 21 repetitions without resting. Afterwards you can rest anywhere from 60 to 90 seconds — or longer — to allow your muscles to recover. If you find yourself struggling to complete each range of motion, either rest more between each set or reduce the load.


  1. Carvalho, L., Junior, R. M., Barreira, J., Schoenfeld, B. J., Orazem, J., & Barroso, R. (2022). Muscle hypertrophy and strength gains after resistance training with different volume-matched loads: a systematic review and meta-analysis. Applied physiology, nutrition, and metabolism = Physiologie appliquee, nutrition et metabolisme, 47(4), 357–368.
  2. Schoenfeld, B. J., & Grgic, J. (2020). Effects of range of motion on muscle development during resistance training interventions: A systematic review. SAGE open medicine, 8, 2050312120901559.
  3. Schoenfeld B. J. (2010). The mechanisms of muscle hypertrophy and their application to resistance training. Journal of strength and conditioning research, 24(10), 2857–2872.
  4. Newmire, D. E., & Willoughby, D. S. (2018). Partial Compared with Full Range of Motion Resistance Training for Muscle Hypertrophy: A Brief Review and an Identification of Potential Mechanisms. Journal of strength and conditioning research, 32(9), 2652–2664.

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