RX is a term usually used in medicine meaning ‘prescription’. Applied to CrossFit workouts, we use the term to determine the exact prescription of a workout, and from that the overall intent or stimulus, which can be described as the effect of a workout on our physical and psychological systems. 

This is significant in that CrossFit training is not just another high intensity training programme, but that each workout is in fact a careful and precise blend of movements designed to elicit a specific response from the body. This makes it necessary to have prescribed movements, loads, and reps i.e ‘RX’ so that we may define exactly what that response should be.

One of the goals of the CrossFit coach is to ensure that every athlete gets the intended stimulus from the workout regardless of their ability level, so we scale movements, loads and reps to preserve that stimulus. The wonderful thing about the CrossFit programme is that everyone can do the same workout, tailored to their specific needs, and achieve the same relative effect. Allowing anyone, at any age and any fitness level to reap the benefits of doing constantly varied functional movements at relative high intensity.

When scaling a workout to preserve the intended stimulus, there are a number of factors that a coach must consider, including:

  1. Energy system
  2. Loading
  3. Volume
  4. Range of motion of the movements
  5. Complexity of the movements

With this in mind we’ll take a look at the following workout, and go into a little more detail on each point.

For time:
Deadlift (100kg/70kg)
Handstand Push Up

This workout (CrossFit benchmark, Diane) pairs barbell lower body pulling with a gymnastic upper body pressing movement. The intended time frame to complete this workout is roughly 3 to 9 minutes. With regard to the 5 points to consider when scaling listed above, we can say that this workout, 

  1. Is mostly anaerobic, taxing predominantly the glycolytic energy system
  2. Is a moderately heavy load
  3. Has relatively low volume
  4. Features hip hinge and overhead pressing movements
  5. Consists of a simple barbell, and moderately complex gymnastic movement

Knowing this information, the coach can now modify the workout for an athlete of any ability. 

Energy System, Loading and Volume

Without going into too much detail, there are 3 energy systems or pathways that the body uses to create and deliver energy. The first is the phosphocreatine pathway, the next is the glycolytic pathway, and the third is the oxidative pathway. The first two are anaerobic, the third is aerobic. 

Though all three energy systems can be working at any one time, the intensity and duration of exercise will dictate which is predominant. This is a key point to understand when selecting the correct loading (weight) and volume (number of reps) for a particular athlete, as getting it wrong can greatly alter the stimulus of the workout.

For example the deadlift in Diane is prescribed at a moderately heavy load, something that is challenging but that could still be lifted for 20+ unbroken reps when fresh. The handstand push up though a challenging gymnastic movement, is intended to be performed for multiple reps and quickly. Both of these efforts require energy derived predominantly from the glycolytic pathway. So if the athlete could manage only a few reps of the deadlift or handstand push up at a time interspersed with longer periods of rest, thus becoming more of a maximal strength test than one of strength/muscular endurance, this would considerably change the feel and metabolic response of the workout.

Conversely, moving a deadlift load that is too light or completing a handstand push up scale that is too easy, would mean the muscles are never really taxed significantly enough to produce the desired metabolic effect, so again our intended stimulus is lost. All of this makes it paramount for the coach to fully understand the capabilities of the athlete when it comes to making scaling decisions.

Range of Motion 

A coach is most likely to need to consider range of motion when scaling a workout for an athlete with a physical limitation, such as an injury or mobility restriction. Other considerations could be for an athlete who is pregnant, or one wishing to avoid or bias working certain muscle groups. With regard to preserving the intended stimulus, it is the task of the coach to provide an alternative movement that meets the athletes needs, while remaining as close as possible to the original movements, loads and reps. 

For example, let’s say we have an athlete with a hand injury and they cannot grip the bar for the deadlift. Knowing that what we’re looking for is a moderately heavy hip hinge movement, the coach could modify the deadlift to a barbell good morning (where the bar rests on the back of the shoulders), so removing the grip element while still maintaining other aspects of the exercise.

Another athlete may have a shoulder injury that limits their ability to press directly overhead. In this case the coach can modify the handstand push up to another body weight pressing movement such as a push up or ring dip providing that particular range of motion is pain free. Depending on the athlete’s ability, the coach may also choose to add load or increase/decrease the reps to ensure the modified movement still meets the intended physical demands of the original exercise.

Poor flexibility is something coaches come across frequently, and is often a cause to scale or modify a workout to ensure the athlete’s safety. An athlete with tight posterior muscles may struggle to achieve the correct deadlift set up position with the bar and plates resting on the floor. In this case the coach could raise the bar up using plates, mats or blocks to a level where the athlete can consistently achieve the correct set up position, and so still use appropriate loading for the workout’s intended stimulus. 

Movement Complexity

Within a workout the complexity of a movement is often part of the challenge. Indeed training high skill movements under fatigue in the gym, prepares us to do so in life and on the field. However doing so requires that the athlete has had a certain amount of practise at that particular skill, has the requisite strength and flexibility to achieve the correct positions, and can demonstrate consistent technique at lower intensities, before it would be appropriate to perform that movement at speed or with increased load. 

For the safety of the athlete the coach therefore may need to reduce the complexity of a movement to a variation or alternative that the athlete is more capable of. As an example, if an athlete had restricted shoulder flexibility and could not achieve a safe position in the handstand, or was not yet able to display consistent technique in the handstand push up, then modifying the handstand push up to a standing double kettlebell push press would remove the complexity of being inverted, and would allow that athlete to achieve the stimulus of the original exercise (overhead pressing) and work at the intended speed.

The need to scale the complexity of a movement is most commonly seen with the Olympic lifts – The Snatch and the Clean & Jerk. Both are remarkably unparalleled exercises for training many elements of fitness, and so have a rightful place in functional movement programming, however both require extensive practise to be able to perform them with heavy loads, at high speeds and for multiple reps. A coach working with a relatively inexperienced athlete may modify the movement to a simpler variation, from a power or squat snatch to a hang power snatch for example, or even to a different exercise that replicates most of the demands of the movement but is easier to perform, such as a kettlebell swing or dumbbell snatch. These simpler variations are a safe and effective way to enable the athlete to get the correct response from the workout, whilst building the motor control, strength and flexibility to perform the more complex variations. 


Scaling is not about making a workout ‘easier’. It is about selecting the right movements, loads and reps that allow the athlete to achieve the intended stimulus, which if done correctly can often increase rather than decrease the relative intensity of the workout.

While working toward completing workouts as prescribed, or RX, often becomes a goal for some, and while eventually being able to complete a workout as RX may represent an increase in strength, fitness and movement competency, it should not be pursued at the expense of correct mechanics, movement technique, athlete safety and the workout stimulus. 

Afterall, our goal in training is to become more fit, functional and capable human beings and for that scaling workouts appropriately is a proven and effective method. Implemented consistently over time, correctly scaling workouts leads to faster progress, reduces injury risk, and promotes longevity, which ultimately makes for a happier and more fulfilling life.

Answers to Some Common Questions

“Why are the prescribed movements and weights often something that many athletes cannot yet do?”

The exact ‘level’ of an RX workout will vary depending on who the programming was intended for, though should always be written at a level that pushes the limits of the fittest athletes within a given population.

Workouts at the CrossFit Games for example are written to test the fittest on earth. There are often movements and loads seen here that even the elite few within the global CrossFit community cannot complete.

At the affiliate level, writing a workout that only a few athletes are capable of completing as prescribed is done so to provide an upper limit, a standard for which all others variants of the workout can be based upon. Once coaches and athletes can determine the stimulus of the workout when completed at the level of the fittest, it becomes much simpler to scale the workout for an athlete of any ability.

It is more effective to meet an athlete’s needs by reducing the loading, volume and complexity of a given workout, rather than increasing. If workouts were instead written at the most basic level, it would mean trying to increase loading, volume and complexity in order to find a degree of challenge for a fitter athlete that is equal to the one faced by someone less fit. Without an upper limit to work to, it then becomes much harder to ensure that every athlete in the class is getting the same stimulus from the workout.

Programming to test the fittest also serves to drive up the fitness levels of all athletes within that population. In the same way as working out with people who are fitter than you will increase your own fitness levels faster than working out alone, constantly facing a workout that pushes the limits of your ability can have the same effect. It forces you to improve, to adapt to the challenge and find ways to overcome it.

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