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When training becomes stale, you might seek a new exercise method to add to your fitness routine to build muscle. Look no further than the 21s workout. This muscle-pumping, high-volume resistance training program will challenge you and your muscles as you rep out 21 total reps per exercise. You may formally know of this workout due to its association with biceps 21 exercises, but don’t just stop there. As you read on, you’ll find that 21s are suitable for most exercises in your fitness regimen. 

I’m thankful for my experience in coaching, which has taught me many things, like finding creativity in workout routines for personal training clients and athletes. I love programming the 21s workout for a fun challenge with end-of-session finishers using movements like bicep curls, tricep extensions, lateral raises, and push-ups. 

RELATED: Beyond the Basic Biceps Curl: How to Gain Arm Mass

Next time you want to switch things up in the gym, give the 21s workout a try, and let me know how it goes!

What is a 21s Workout?

Brace yourself because the 21s workout isn’t for the faint-hearted; it’s a challenge that will push your limits, but it’s fun, I promise. Here’s the breakdown of how it’s done: start by cranking out seven bottom-half reps of bicep curls, stopping right at a 90-degree angle with the arms; you’re just getting started. Now, switch it up and do seven top-half bicep curls. You’re at the halfway point! Finish strong with seven complete repetitions focusing on a full ROM (or full range of motion). 

  1. 7 bottom-half reps
  2. 7 top-half reps
  3. 7 complete reps

That’s the magic formula for the 21s workout.

Don’t limit yourself to just bicep exercises for the 21s workout. It’s also great for full-body and traditional bodybuilding workouts.

Common Exercises for the 21s Workout

Grab one of the best Olympic barbells or a pair of the best dumbbells, or take a seat on the leg curl machine as I take you through a few of the best 21s exercises. I—a Certified Strength and Conditioning Specialist (CSCS)—love programming for the 21s workout. I’ve laid out the basics for each movement, but it’s up to you to make it a 21s workout by incorporating the 7-7-7 range of motion listed above. And don’t worry, bicep workouts are included.

Biceps Curl

Why do it: Who doesn’t want a pair of show-ready biceps? Bicep curls are a classic bodybuilding movement aimed at increasing strength and size in your arms. Use a variety of exercises in your bicep 21s workout for an arm-pumping finisher. The options are limitless: straight-bar curls, dumbbell curls, hammer curls, EZ-bar curls (my personal favorite), or even kettlebell curls should work nicely.

RELATED: Curl Bar Workouts

How to do it:

  1. Stand with your feet hip-width apart.
  2. Hold a straight bar, a curl bar, or a pair of dumbbells using an underhand grip, keeping the palms facing forward.
  3. Curl the barbell or dumbbell until it nearly touches your shoulder.
  4. Slowly lower the barbell or dumbbell back to the starting position.
  5. Repeat for desired reps.
EZ Bar Curl

Bench Press

Why do it: You have the bench press to thank for Monday’s gym-labeling of “International Chest Day.” The bench press is one of the most effective free weight exercises for building upper body strength. Position yourself on one of the best weight benches, and crank out 21 blood-pumping reps to grow your chest, delts, and triceps. 

How to do it:

  1. Lie on a flat bench with a barbell positioned above your chin and your feet flat on the floor.
  2. Place your hands shoulder-width apart and grip the barbell.
  3. Brace your core, squeeze your upper back, and push the barbell off the rack, placing it above your chest.
  4. Bend your elbows and slowly lower the barbell just below your chest line.
  5. Squeeze your chest and drive the barbell straight up until you reach lockout.
  6. Repeat for desired sets and reps.
woman doing bench press

Back Squat

Why do it: Do you want a defined lower body, increased leg strength, and the bonus of improved mobility? Two words: back squat. The back squat is an essential exercise for any gym-goer looking to enhance these attributes while also targeting and developing your quads, hamstrings, and glutes. Working through a full range of motion on the last seven reps makes the back squat great for improving mobility.

How to do it:

  1. Place your hands slightly outside of shoulder width.
  2. Walk yourself under the barbell, squeeze your traps, and place the bar on your upper back.
  3. Step back from the squat rack and position your feet hip-width apart.
  4. Brace your core, then bend your knees as you squat down slowly.
  5. Once you hit your squat depth, drive through your legs to stand up.
  6. Repeat for desired sets and reps.

Expert tip: Squat to a comfortable depth for you, ensuring your feet stay flat throughout the movement.

RELATED: Squat Workout

woman doing back squat

Hamstring Curl

Why do it: Think of the seated leg curl as the equivalent of a bicep curl but for your lower body. Whether you’re at the gym or learning how to do hamstring curls at home, any variation of this exercise is excellent for isolating and growing your hamstring muscles. When you incorporate the seated leg curl into a 21s workout, you can emphasize enhancing the strength and size of your hamstrings.

How to do it:

  1. Take a seat in the leg curl machine and adjust the curl pad, seat, and weight stack
  2. Put your legs on the curl pad, with the pad touching slightly above your ankles. Grip the handles. 
  3. Pull down the curl pad with your hamstrings, curling your legs.
  4. Allow your legs to straighten back to the start position with control.
  5. Repeat for desired sets and reps.

Lateral Raise

Why do it: Lateral raises are a great isolation exercise for growing boulder shoulders. As you work on defining your upper arms, you’ll also be targeting your traps. The best options for lateral raises include standing or seated positions, dumbbell, cable machine, or banded variations, and then performing them as a bilateral (two arms) or unilateral (one arm) movement.  

How to do it:

  1. Stand with your arms at your sides, keeping your elbows slightly bent, and hold a dumbbell in each hand.
  2. Squeeze your delts and lift your arms until they reach about shoulder height.
  3. Lower your arms back to the starting position with control.
  4. Repeat for desired sets and reps.

Expert tip: Switch up your arm angle to target more posterior (back) or anterior (front) delts.

RELATED: Best Shoulder Exercises

dumbbell lateral raise gif

Benefits of the 21s Workout

Keeps Your Workouts Fun

Introducing creative and challenging workouts into your routine can inject an enjoyable and motivating element into your fitness regimen. Why is this important? It sustains your enthusiasm and eagerness for training! Additionally, the primary objective of exercise is to expose your body to a stimulus slightly beyond its comfort zone, encouraging it to adapt and improve.

I recommend altering your workout routine every four to eight weeks, depending on the duration of your consistent training. This way, you can have fun, push your limits, and stay enthusiastic about making continual progress toward your fitness goals.

Increases Muscle Size

Research has shown that engaging in higher-volume resistance training sessions is an effective way to increase muscle growth. A December 2018 study published in the Journal of Medicine and Science in Sports and Exercise1 discovered significant increases in muscle size when individuals followed high-volume resistance training regimens1. The 21s workout applies this training style by incorporating high-volume sets that involve partial and complete repetitions in a combination of compound and isolation exercises.

RELATED: Full-Body Compound Workout

Woman squatting with Vulcan Buffalo

Increases Muscle Endurance

We often discuss muscle size and strength, but what about endurance? Simply put, muscle endurance is the ability to resist muscle fatigue. Think of the last time you fought through high-rep squats. Improvements in local muscular endurance can counteract that muscle “burning” feeling you fell in love with in your quads (just kidding, no one enjoys that feeling). Research shows that training with sets of 15+ repetitions2 is ideal for achieving improvements in local muscular endurance. 

RELATED: Cross-Training Exercises

21s Workout: Final Thoughts 

Coming from a CSCS-certified coach, I don’t suggest working out with the 21s exercises for an extended period. However, this workout has pivotal benefits to help you increase muscle size and strength while keeping your training fun. Use it for full-body workouts or split routines. I love using this rep scheme in accessory circuits as finishers for the clients and athletes I work with. The key is using the 21s workout at a time when it makes sense and is appropriate. 

To summarize:

  • 21s workout adds a fun (and challenging) twist to your typical workout routine.
  • High-volume training helps build muscle and improve muscular strength and endurance.
  • Start with light weights, and ensure you have the energy to finish the workout—hydration and nutrition also play a role. 
  • Use isolation movements in your accessory circuits or secondary workout days.
  • For compound exercises (back squats, bench presses, pull-ups, etc.), use extended rest periods for adequate recovery and keep the working sets lower.

21s Workout: FAQs

What are 21s in exercise?

A 21s exercise involves doing seven repetitions of the bottom half of a movement, followed by seven repetitions of the top half, and finally, seven complete repetitions, giving you the 21s workout. The 21s workout is a high-volume resistance training program that combines partial and complete repetitions. 

While this workout can be enjoyable, it’s also quite challenging. I recommend incorporating it into your routine for one compound exercise and pairing it with one to three accessory movements, using upper and lower body splits. 

Last but not least, be sure to prioritize your mobility, nutrition, and hydration for recovery.

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Can you do 21s for the chest?

21s are for more than just the biceps. There are only a few exercises that this workout might not apply to; chest workouts are not one of those. Whether you’re doing bench press, incline dumbbell bench press, or cable flys, 21s have the potential to help you build muscle. Two boxes to check are if you’re using appropriate weight and maintaining excellent exercise technique.

What are the benefits of doing a 21s workout?

Besides a creative change to your typical workouts, the 21s workout can build muscle size and local muscular endurance. Not to mention, you’ll be reaping all the other benefits of regular physical activity! This workout also provides the advantages of partial reps and time under tension principles for your workout program, helping train various muscle groups.

RELATED: How to Build Muscle


  1. Schoenfeld BJ, Contreras B, Krieger J, et al. Resistance Training Volume Enhances Muscle Hypertrophy but Not Strength in Trained Men. Med Sci Sports Exerc. 2019;51(1):94-103. doi:10.1249/MSS.0000000000001764
  2. Schoenfeld BJ, Grgic J, Van Every DW, Plotkin DL. Loading Recommendations for Muscle Strength, Hypertrophy, and Local Endurance: A Re-Examination of the Repetition Continuum. Sports (Basel). 2021;9(2):32. Published 2021 Feb 22. doi:10.3390/sports9020032

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