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Applied Functional Science Clinic - What to Know For Your First Day

by Kelsey Diaz


Copyright Disclaimer:
This article is not intended to replace a certification in Applied Functional Science or to infringe upon copyrighted material, but rather to share some basic concepts behind a certification available to physical therapists.

Deciphering your first day at an AFS-style physical therapy clinic

As seen in the article, The "Alphabet Soup" of Physical Therapy Certifications, Applied Functional Science (AFS) is one of the many certifications available to physical therapists. It is not a board-certified specialty and you don’t need to be a physical therapist to practice it, but AFS was developed by a physical therapist.

According to the AFS website, Gary Gray (allegedly the same guy who created the BAPS board), developed AFS as an approach to studying movement that blends physical, biological, and behavioral sciences.

Hopefully you can let your personal PT style shine when you enter the real world as a PT. However, if you’re a new grad set on outpatient ortho you should consider what, if any, treatment preference exists at your prospective place of employment.

I accepted a physical therapy position at an outpatient orthopedic clinic that practices Applied Functional Science and I am currently in the process of getting my Certification in Applied Function Science (CAFS). Before my first day at this clinic, I had no prior experience with AFS, and reading my first patient note was like deciphering a secret code.

Movement basics in Applied Functional Science

AFS operates under the assumption that the practitioner already has a sound understanding of movement basics. Think of the effects that gravity, ground reaction forces, mass, and momentum have on your patient. You learned all of that in PT school, so you’re good here!

Observation essentials

Observation is a crucial component of the objective portion of an Applied Functional Science evaluation. There are 10 observation essentials that practitioners of AFS believe should be considered throughout movement evaluation and exercise prescription.

The observation essentials include terms like action, environment, position, and load. Most of these observation essentials are familiar to someone with a PT degree, with the exception of the term “driver."

The driving force

In AFS, the “driver” is the leading force that directs a movement. When you perform a lawnmower-style lateral lunge and reach toward your foot, your arm is the driver. Virtually any body part can be a driver.

Using AFS, movement can be altered by simply manipulating the driver. By changing the driver, the chain reaction through the rest of the body is changed too.

Authentic versus un-authentic movement

The idea of functional exercise is not new to physical therapy but it is paramount to the practice of AFS. Authentic movements are those that a person or patient performs in his or her everyday life. An AFS-style treatment is mainly composed of movements that are authentic but may also operate on a sliding scale of un-authentic to authentic.

For example, most people don’t go through their day doing sets of calf raises, but they do need gastrocnemius strength for daily tasks, like push-off during gait or to plantarflex to reach for something on a high shelf. A calf raise may be a less authentic exercise prescribed to help accomplish a more authentic task.

Life in 3D

The AFS tribe refers to it as “three-dimensional”, but really what they mean is tri-planar. They emphasize that all muscles and joints move in the sagittal, frontal, and transverse planes and that training or rehabilitation should also be performed in all 3 planes of motion.

Take the shoulder, for example. It’s easier to see that during flexion in the frontal plane, the scapula must upwardly rotate. However, it’s also protracting and tilting posteriorly in the transverse and sagittal planes. If movement isn’t appropriately synchronized in all 3 planes, normal flexion can’t happen.

The exercise is the test and the test is the exercise

An AFS PT evaluation looks a lot different than what you learned in school. It relies less on manual muscle tests and more on observation of deficiencies during movement. When you find a movement that is challenging or painful for a patient, you know what you need to incorporate into your treatment.

Individuality through “tweakology”

“Tweakology” is a term coined by Gary Gray that essentially means adapting an exercise by changing certain components. If a patient has difficulty doing a squat without lifting his or her heels off the ground, you can “tweak” the position of the feet into external rotation, decreasing the stretch on the heel cord.

Enter the matrix

With the tri-planar or “3D” view of authentic movement, the “matrix” was born. In AFS, a matrix is a series of exercises formulated by tweaking the plane, position, or other elements of one exercise. The number of matrices that can be created for one exercise is exponential. For example, a squat matrix can be created by tweaking the positioning of the feet in all 3 planes.

Triple X

An AFS treatment plan is full of exercises and acronyms that might look like glyphs if it’s your first day in an AFS clinic without prior experience. This is where the code comes in.

So you open your patient's exercise flow sheet and see "xxx/lxx/rxx squat matrix." This is shorthand for a squat matrix. Each x is a placeholder for a plane of motion: sagittal, frontal, and transverse. X represents a neutral position. The l and the r in this example indicate that the sagittal plane of the foot placement was altered for a left-skewed squat (left leg in front) and a right-skewed squat.

In the frontal plane, foot positioning can be narrow or wide, written as xxx/xnx/xwx. Finally, xx/xxe/xxi means neutral squat, squat with feet externally rotated in the transverse plane, and with feet internally rotated in the transverse plane.

Common versus uncommon

For lack of a better term, another common phrase in the AFS dictionary is “common versus uncommon.” The definitions are somewhat subjective, but they do make sense.

Take the lunge, for example. If you are going to do a lateral lunge to your right, it is more common for you to use your right foot. It would be less common for you to lunge to the right with your left foot. This is the common versus uncommon concept in a nutshell.

Transformational zones

Along with having a keen eye for biomechanics, Applied Functional Science practitioners should be able to recognize where one motion transitions to another. Gait is an easy illustration.

The first transformational zone is considered initial contact to mid-stance. Mid-stance to swing is the second transformational zone. There’s more code to decipher for this. Transformational zones are usually documented as "TZ1" and "TZ2."


In class, we learn manual techniques with the patient usually lying down or sitting on a treatment table. The functional manual reaction is the AFS twist on manual therapy.

Instead of performing a posterior talar glide on a patient sitting on the edge of a table, you might perform it while they are taking a step or performing a lunge instead. This is similar to Mulligan's Mobilization with Movement.

The pros of Applied Functional Science

  • Creativity: Between drivers and matrices, Applied Functional Science promotes creativity and individuality of treatment. “Tweakology” gets you thinking outside the box and allows you to create exercises specific to each patient.
  • Parallel to the ICF model: AFS mirrors the World Health Organization’s International Classification of Functioning, Disability, and Health model by promoting functional exercises crucial to a person’s participation in his or her various life roles.
  • Off the treatment table: Applied Functional Science gets patients moving the way they do in real life and may help save the PT’s body too.
  • Biomechanics review: AFS is heavy on biomechanics, so if you decide to go for your CAFS, you’ll get a healthy dose of arthrokinematics review.

The cons of Applied Functional Science

  • “Guruism”: There is often a stigma in following a treatment touted by one expert. Make sure you believe in your treatment and that you’re not just taking someone’s word that it works.
  • Cost: The Certification in Applied Functional Science (CAFS) will run you $549. If your clinic wants you to be certified, find out if they will cover some, if not all, of the certification fees.
  • Special cases: Some patients and injuries lend themselves well to an Applied Functional Science style treatment. Others, like a carpal tunnel release, may be more difficult to tackle using the AFS mindset, but it can be done.
  • Objectifying observation: When you rely less on manual muscle testing and goniometry and more on movement observations, you have to find a way to objectify what you see, so that change can be measured.

Have an open mind with a healthy dose of skepticism

The general consensus here at NGPT is to fake it 'till you make it when you finally enter the real world as a PT. The same goes for Applied Functional Science! Observe people closely, put your hands on them as they move, and seek mentorship from a more experienced AFS PT.

Approach new modes of physical therapy with an open mind and a healthy dose of skepticism. If you are interviewing at an outpatient orthopedic clinic with a particular treatment preference, don’t be afraid to ask why, and don’t feel obligated to conform to their style if you don’t believe in it (although you may want to look for another job).

Pursue evidence to support your actions in the clinic and allow extra certifications like CAFS to be a complement to the knowledge and skills you gained in school, not a replacement.

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