Why Does CrossFit Use 21-15-9? Find Out.

If you’ve set foot in a CrossFit gym you may well have seen this curios rep scheme. But why is it synonymous with CrossFit?

The 1st of 45 Box Jumps where a smile can still be seen

21-15-9 is a rep scheme that was developed by Greg Glassman, and then proliferated by CrossFit. The repetitions (reps) decrease by 6 each round. It carries a simple theory: that your power output should remain the same throughout the workout because the workout is short, thus a decrease in reps allows for the effort to be sustained for that time period. This theory is known as the “Decay Curve”.

Total number of repetitions (reps)

The total number of reps is 45 (21+15+9), and the workout intent is a fast sprint.

For intermediate or advanced athletes, the idea is that all 21, 15 and 9 reps should be unbroken.

Therefore, you should be selecting a weight or scaling of each movement that permits you to do this unbroken – or in other other words, without splitting the sets down into smaller chunks.

21-15-9 aims to overcome the Decay Curve

21-15-9 is a fast workout

These type of workouts are normally specifically programmed to not be too heavy at RX (prescribed) weight, as the idea is it invariably should be an unbroken WOD to achieve the correct stimulus.

As one’s cardiorespiratory endurance (V02 Max) improves, you should be able to do the sets unbroken easier, and then heavier if scaling.

Eventually, you would be able to do the workout 21-15-9 unbroken and at the prescribed weight.

This BGH article looks deeper into cardiorespiratory endurance.

Elite level 21-15-9

To see what this looks like on an Elite (professional) CrossFit athlete level, this video succinctly shows how a 21-15-9 WOD can be done.

Dan Bailey smashes the world record in 2012 (with nobody yet having beaten him) and he is ‘no repped’ (disqualified reps for not meeting standards) in his set of 15!

“Diane” 21-15-9 Deadlifts 100kg and Handstand Push Ups

Do I have To Do 21-15-9 Unbroken?

It needs to be said – it is not a prerequisite that you execute 21-15-9 as an unbroken workout.

The beauty of the sport is its infinite scaling. So depending on where you are on your journey, you can still just do the 21’s, 15’s and 9’s to a level and pace that suits you.


There is a but….you need to choose a scaling that you are doing a large number of reps, say 11 and 10 for the 21, then 10 and 5 for 15, and 5 and 4 for the 9.

You should not be doing singles in a 21-15-9

If athletes or members find themselves doing singles all the way on the 21-15-9 rep scheme, they have gone too heavy and are completely missing the intention behind the workout. Thus, a review of the weight or scaling must be undertaken so you can do the work as required.

The idea is that you maintain a sustained output in sets 1, 2 and 3, despite fatigue setting in.

The WOD, as noted, above is one of a fast pace. It’s the polar opposite of a chipper.

How Does The 21-15-9 Rep Scheme Help Me Get Fitter?

The rep scheme is just one of many building blocks that helps you get fitter.

Unbroken Wall Balls all the way?
Unbroken Wall Balls all the way?

As detailed earlier, the objective is to maintain the pace for all 3 rounds (or 45 repetitions).

There are 10 domains that CrossFit utilises to create a fitter human being.

The CrossFit philosophy is one that commands the winners each year what they call ‘The Fittest on Earth’. (You can read more about this here in a Best Gym Hacks article on how CrossFit Works).

‘The Fittest on Earth’

Whilst The Fittest on Earth is a very dramatic title (and I personally find it a bit cringe to be honest), you can see CrossFit’s point when looking at the methodology and the outcome it produces.

World class Athletes

For example, athletes at The Crossfit Games will be Olympic lifting world-class weights, followed by rowing a marathon, then swimming and paddle boarding kilometres, with a whole host of gymnastics and conventional and non-conventional exercises thrown in over 5 days – some of which are a surprise and no prior training has been undertaken for it.

The rounded fitness of these individuals you would not find in any other sport, and thus the quest to become the Fittest on Earth comes into its own.

The 21-15-9 rep scheme is one small part that helps these individuals get to that level. It’s also one piece for the everyday CrossFitter become fitter.

A useful baseline

Predictably then, the idea that one can find a peak baseline using the scheme – and stick to it – is a useful metric to have and to know.

As you get fitter in a cardiovascular sense, this baseline should allow you to increase its intensity, i.e use a heavier weight or go a bit faster.

Likewise, when your cardiovascular fitness (or cardio for short) is lacking, you’ll find that your peak baseline is lower, so will need to go lighter or slower. Think post 2-week all-inclusive holiday and first session back in the gym….

Variation is key

But, only doing 21-15-9 WODs and expecting to just get fitter is not the case.

The CrossFit movements are functional, full-body movements that generate a great deal of power, and virtuosity in these movements requires instruction, practice and refinement. The movements are tremendously effective for producing fitness, but they are complicated enough that no teaching tools can be ignored.

Greg Glassman – Founder of CrossFit

What Is The Decay Curve Theory?

The Decay Curve posits that over a measured period of time, there is a direct correlation in the reduction of performance.

The below visual representation is how this downward trend might look in an area chart.

Decay Curve

By deploying a 21-15-9 rep scheme, the ideation around this principle is that this curve is avoided, and the activity being engaged does not suffer from ‘decay’, but rather that it remains a constant.

Consistency for the win

The chart below indicates what the output over time linear plot might look like, in this instance.

It denotes a nice consistent line, showing that performance (output) is not compromised in the time period – in other words, the intent of a CrossFit 21-15-9 rep scheme.

21-15-9 output over time in an area chart

It helps substantiate the point of maintaining full send in each round, with maximum output also being maintained.

Other Types of CrossFit Workouts

Bear in mind, you also need to do longer WODs; heavier and longer WODs; interval training at high intensity WODs (see this Best Gym Hacks article here for more info on this); running, rowing or biking-based medium or long-distance WODs, low heart rate strength workouts, chipper workouts, sprint chippers, and many other variations that cover a lot of ground.

By doing this, you become fitter in the round, and not just pigeonholed into being excellent at one or two things; rather the aim is to be good at 10 things.

Examples of staple short CrossFit WODs with familiar rep schemes

Some examples of other workout types used in CrossFit to make you fitter include:

Short and light, akin to 21-15-9…


  • 9-7-5 Reps For Time
  • Muscle-Ups
  • Squat Snatches (61/43kg / 135/95 lbs)

This contains technical movements which, although short, the number of people RXing this WOD and going unbroken would be significantly less than people doing Fran. (Fran times 3 – 6.5 mins)

The reason for this, a lot of people who can RX Fran unbroken (21-15-9 pull-ups and thrusters 135/95lbs), could also RX Amanda, but mostly they would not do Amanda unbroken.

The concept is similar, but the strategy is different. Time approx 4-8 mins.

Miko’s Triangle – interval based, also focussed on maintaining pace.

  • EMOM (every minute on the minute) for 39 minutes
  • 1-minute Row
  • 1-minute SkiErg
  • 1-minute Assault Bike
  • 1-minute Rest
  • Set a single number of calories and complete that amount of work each minute – every minute.

Death by Anything. Thrusters, Burpees, Clean, Floor Press, Muscle Ups – choose your poison

  • EMOM For as Long as Possible
  • 1 Rep in the first minute
  • 2 Reps in the second minute
  • 3 Reps in the third minute
  • etc.

This WOD gets harder as the reps increase and rest period reduces.

Linda – lower on the heart rate scale. More strength based

  • 10-9-8-7-6-5-4-3-2-1 Reps, For Time
  • Deadlift (1½ bodyweight)
  • Bench Press (bodyweight)
  • Clean (¾ bodyweight)
You can get fit sitting down

Row Single Distance

  • 2k for time

Using the rowing monitor, you can easily track your 500m split pace and try to stick to it for the entity.

Knowing your 500m row pace is a good metric for all Rowing, whether it be intervals, bookends in workouts, repeated in a WOD for rounds, or just a single distance.

An average CrossFitter 500m row pace should be between 1:42 – 2:02. The longer the single distance, the more often this pace goes up in time (so down in performance).

The Seven – a medium-long chipper (its called a chipper because you chip away at it; or you feel like you’ve gone through a wood chipper after it).

  • 7 Rounds For Time
  • 7 Handstand Push-Ups
  • 7 Thrusters (135/95 lb)
  • 7 Knees-to-Elbows
  • 7 Deadlifts (245/165 lb)
  • 7 Burpees
  • 7 Kettlebell Swings (2/1.5 pood)
  • 7 Pull-Ups

The 7 reps should ideally be unbroken for all movements. This would make for consistent round times. What catches most people out that RX this WOD is the Thrusters or HSPU. Time approx 28 – 35 mins.

This is a very short list of what other WODs are used in CrossFit to get you fitter. It’s not only about the 21-15-9!

For 101 FREE 21-15-9 workouts, check out WODWells link right here! What a little goldmine

What Are Some Examples of 21-15-9 Workouts?

Here’s a round-up of some choice few 21-15-9 WOD’s, the intent of which fits Greg Glassman’s brief of short and fast:

The Coop

  • For Time
  • 21-15-9 reps of:
  • Pull-Ups
  • Bench Presses (135/95 lb)
  • Rest 3 minutes
  • 9-15-21 reps of:
  • Push-Ups
  • Deadlifts (225/155 lb)


  • 21-15-9 Reps for Time
  • Thrusters (135/95 lb)
  • Chest-to-Bar Pull-Ups


  • 21-15-9 Reps for Time
  • Power Cleans (95/65 lb)
  • Box Jumps (24/20 in)
  • Toes-to-Bars

Donkey Kong

  • 21-15-9 Reps for Time
  • Burpees
  • Kettlebell Swings (24/16 kg)
  • Box Jumps (24/20 in)
  • Perform 6 Lunges after each exercise

Freddie Krueger

  • 21-15-9 Reps for Time
  • Kettlebell Swings (70/53 lb)
  • Burpees

Sugar Daddy

  • For Time
  • 21-15-9 Deadlifts (225/155 lb)
  • 400 meter Run

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What the aftermath of a 21-15-9 WOD can look like
What the aftermath of a 21-15-9 WOD can look like

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