Yoga Poses Deconstructed: A Master Class in Yoga Modifications

Posted by Lauren Eirk

yoga instructor posing in front of lake

Hatha yoga is the branch of yoga that deals with the physical body, and its early practice focused on rigorous discipline. In hatha tradition, ASANAS (yoga postures) and PRANAYAMA (breathing exercises) were seen as preparation for deeper spiritual practices such as meditation (Muktibodhananda 1998). 

Today, Western cultures have adopted hatha yoga, and many people now practice it for health and fitness, seeking to lower stress levels, improve overall strength and increase flexibility. Yoga, after all, is a great addition to any fitness professional's toolbox. 

To achieve this last goal—flexibility—when performing an asana, various involved joints will ideally be at the end of their available range of motion. For this to happen, it is crucial that the muscles supporting these joints be responsive and able to fully contract and stabilize the joints.

Using the NASM Optimum Performance Training™ model for perspective, this interdependency can be seen in Stabilization Endurance Training (Phase 1). In this phase, the focus is “to increase muscular endurance [a muscle’s ability to contract for an extended period] and stability while developing optimal neuromuscular efficiency (coordination)” (NASM 2018). In the OPT™ model, the result of developing muscular endurance and joint stability is improved ROM over time.

The outcome of any yoga position is also based on the interrelationship of involved joint structures and the muscles around them. Joint stability flows naturally from increases in strength, which can increase ROM, as well.

Monitoring and Evaluating a Student’s Progress

The practice of hatha yoga should focus on training within the student’s available joint range, with careful monitoring of his or her daily ability. There should be constant attention to the various modifications that may be needed along the way.

Using techniques similar to those that fitness professionals employ to assess movement patterns in other modes of exercise, yoga instructors can examine the biomechanical aspects of each posture to help every participant make the greatest possible gains.

Here, I will break down three popular yoga poses from the ground up and explain how to perform a bilateral evaluation and joint assessment for each of them. Learning how to deconstruct these postures will offer helpful insights on how you can similarly assess clients when they practice other asanas.

Downward-Facing Dog

Of the 84 classic hatha yoga asanas, downward-facing dog (adho mukha svanasana) is one of the best-recognized and most-often-demonstrated poses in Western culture. When performed strategically, this pose is a great strength builder for shoulders, abdominals, spinal erectors, hip flexors and ankles. It is also an inversion (head below heart), which adds to its complexity, owing to the influences of ground forces (gravity) and friction.

yoga clients doing downward facing dog during class


Downward-facing dog involves the mechanical relationships between shoulders, trunk, hips and knees. The pose uses these joints:

  • ankle (dorsiflexion)
  • knee (extension)
  • hip (flexion)
  • trunk (extension
  • shoulder (flexion/upward rotation)
  • elbow (extension)
  • wrist (extension with pronation, palms to floor)


If participants are new to yoga or have certain physical limitations, it may be preferable to first evaluate them using seated staff pose (dandasana). At the hip joint, staff pose is similar to downward-facing dog, with hips flexed to 90 degrees (as much as possible) and knees in extension (as much as possible). Staff pose allows you to look at the relationships of the ankles, knees, hips and trunk without participants being inverted (upside-down) as they are in downward-facing dog. If sitting on the floor is a challenge for a participant, then a blanket, bolster or block can be placed under the buttocks to increase the degree of hip flexion or to enable greater knee extension.

If the staff pose outcome is positive, participants may be ready to perform downward-facing dog. Be aware that, because of the inverted position and the addition of full shoulder flexion, the challenge will increase. Modifications (below) may be necessary until strength grows and ROM improves.


The common goal of downward-facing dog is to achieve a 90-degree angle at the hip. Many participants will not be able to achieve this much range because of a combination of the structure of the joints involved, the degree of participation of muscles supporting those joints, and the lever lengths of the upper and lower extremities. There are various points to consider:

  • lever lengths of torso (trunk), femur, tibia, radius, ulna, humerus
  • previous injury affecting muscular participation of involved joints
  • limits of trunk extension
  • amount of contact surface in talocrural (ankle) joints and/or acetabulofemoral (hip) joints
  • orientation of hip joint (anatomical position)
  • shape and size of femoral head and femoral neck
  • weakness of hip flexor muscles (inability to achieve/hold desired position)
  • influence of shoulder on trunk and pelvic position (participants may need to flex knees to allow for current amount of hip flexion and to decrease tension in muscles that cross the hip and knee joints)

modification of downward facing dog

Photos: Megan Resch


  • Flex the knees to reduce muscular pull on the hips.
  • Shift body weight forward to limit shoulder flexion (for upper-extremity issues).
  • Place an object under the “heels” of the palms and/or feet to accommodate current joint ranges and lever lengths.
  • Place a prop (such as a yoga block) between the upper thighs to allow for increased muscular participation in hip adduction and internal rotation, if desired.


  • Raise one leg (hip extension) for three-legged downward dog.
  • Externally rotate the extended hip.
  • Add plantar flexion at the ankle joint with feet in contact with the floor.
  • Vary the overall distance from foot to hand (i.e., walk the hands forward or backward).
  • Place the hands and feet on a frictionless surface to increase muscular participation.

yoga clients doing extended triangle pose

Extended Triangle

Although extended triangle is touted for strengthening the lower extremities and trunk (core), this pose also deals with ground reaction forces, with the feet pressing into the floor and the force of the floor pushing up into the feet. Our muscular system is responding, not only to this action-reaction set of forces, but also to the influence of friction as one foot relates to the other on the surface of the mat or floor.


Standing poses are often presented in beginning yoga classes and are considered foundational to any practice. However, standing poses are quite complex, as we see with triangle pose (utthita trikonasana). This is because “each part of a joint has one or more specific functions that are essential for overall performance of the joint. Therefore, anything that affects one part of a joint will disrupt the total function of the joint” (Levangie & Norkin 2011). When we see so many joints working together, we have to realize that the overall outcome of a yoga asana is determined by the structure and function of every individual joint that is involved. For triangle pose, that means these joints:

  • ankle (dorsiflexion, pushing into plantar flexion)
  • subtalar (inversion)
  • knee (extension)
  • hip (flexion, abduction, internal rotation of one hip and external rotation of the other)
  • trunk (lateral flexion, rotation)
  • shoulder (abduction)
  • elbow (extension)


Many other standing poses resemble this pose, with the hips bilaterally abducted and the participant moving the trunk over the legs in an attempt to reach a hand to the floor (or shin/ankle). In the classic text Light on Yoga, B.K.S. Iyengar discusses the importance of the foot and its effect on the entire body, saying, “Owing to our faulty method of standing and not distributing the body weight evenly on the feet, we acquire specific deformities” (Iyengar 1979).

In preparation for triangle pose, it is beneficial to evaluate ROM in the hip joints in both standing and non-weight-bearing (seated) variations. The end position will require not only bilateral hip abduction but a significant amount of hip rotation, so performing an evaluation while standing as well as seated is beneficial. 

Rotation of the hip can also be evaluated in supine, with the knee in extension, as well as in hip flexion, with the hip achieving a flexed position closer to 90 degrees. The next step is evaluating the degree of hip abduction, both left and right, in a non-weight-bearing scenario.

Many yoga books give blanket cues as to how the pose should be performed. Light on Yoga directs the student to “inhale deeply and with a jump spread apart the legs sideways 3 to 3 ½ feet” and to “turn the right foot sideways 90 degrees to the right” (Iyengar 1979). In reality, many students will not be able to achieve this type of rotation owing to the structure of—and available range within—the hip, lower leg and foot. For this reason, it may be wise to also evaluate the foot and ankle, checking for mobility in both dorsiflexion and plantar flexion, as well as side to side (abduction and adduction).

extended triangle yoga modification


Any issues with the lower extremities will greatly affect the trunk. It is often taught that the goal of the pose is to touch the foot by flexing the trunk laterally, while bilaterally abducting at the shoulders to achieve the shape of the triangle. Many practitioners will never be able to do this. Expressions of triangle pose vary for multiple reasons:

  • lever lengths of torso (trunk), femur, tibia, radius, ulna, humerus
  • previous injury affecting muscular participation of involved joints
  • mobility of trunk in lateral flexion, rotation and extension
  • mobility of hip joints affecting trunk mobility
  • ROM of hip joint, rear foot and midfoot
  • alignment of foot, knee and hip, affecting stance, width and foot placement
  • neuromuscular participation and orchestration


  • Place a stability ball between the legs to stimulate hip adduction.
  • Push the feet away from each other into the yoga mat to stimulate hip abduction.
  • Hold a weighted object over the forward leg at a distance from the hip joint to challenge the muscles to maintain hip and trunk position, avoiding excessive lateral flexion.
  • Change shoulder position—for example, by flexing one or both shoulders overhead to challenge the trunk and shoulder muscles.
  • Use a resistance band between the hands to stimulate scapular-retraction musculature.

Seated Twist

seated twist yoga movement

Also known as “Half Lord of the Fishes” pose (ardha matsyendrasana), this asana is commonly thought to be a “neutralizing” posture used to balance a series of antagonistic movements, as in hip flexion and extension. To safely rotate the trunk while in a seated position, practitioners must work to maintain adequate trunk extension.


The degree of overall rotation that an individual can achieve in this pose will depend upon the motion capabilities of the joints in the spine, hips and shoulders. These are the joints involved:

  • knee (flexion)
  • hip (flexion, abduction/adduction, internal/external rotation)
  • trunk (extension, rotation)
  • shoulder (retraction, protraction)


Even though many yoga poses involve rotation, there are considerable challenges to being in a seated position, which increases the forces on the intervertebral disks. If a student cannot sit upright without sinking into spinal flexion, for example, we know there is a higher risk of injury. 

Trunk rotation will always cause the annulus fibrosus (cartilage surrounding and protecting the gel-like nucleus pulposus of the intervertebral disk) to stretch in order to accommodate the pose. This can be a problem if there is already a weakness in the disk. Additionally, we must consider that there may already be wear to the annulus fibrosus from past repeated stress.

Adalbert Kapandji, MD, says the “nucleus is therefore strongly compressed and its internal pressure rises in proportion to the degree of rotation. This explains why combined flexion and axial rotation will tend to tear the annulus by increasing the pressure inside the nucleus and driving it posteriorly though potential cracks in the annulus” (Kapandji 2008).


Researchers compared the effects of twisting versus no twisting on the mechanical properties of the interlamellar matrix (fibers within the annulus fibrosus). In the study conclusion, the authors stated that twisting, regardless of compression exposure, negatively affected the strength of the interlamellar matrix. 

What’s more, when the rotation was combined with repetitive flexion, there was a more frequent occurrence of intervertebral disk herniation (Harvey-Burgess 1958). A passive twist—using the upper extremity to pull oneself around—can elicit greater overall ROM but potentially with some loss of neuromuscular control, which can cause injury to the spine. Various issues affect the expression of this pose:

  • pregnancy (Note: Women should not practice this pose during later stages of pregnancy.)
  • spinal disk issues (fusion, degeneration)
  • weakness of muscles that cross the trunk, hip and knee
  • position of acetabulum; shape and size of femoral head and neck
  • neuromuscular participation and orchestration of spinal and trunk muscles


  • Stand, holding onto a chair for balance, and raise one hip and knee to 90 degrees.
  • Sit on a chair with hip and knee at 90 degrees
  • Sit on blankets to decrease hip and knee flexion.
  • Sit with one knee in flexion and one in extension.
  • Avoid hip adduction in any variation from the ipsilateral hip
  • Change the hand and elbow position of the contralateral upper extremity.


  • Add a counter-rotation in cervical motion.
  • Sit on a stability ball if greater neuromuscular control is needed in various joints.
  • Anchor a resistance band away from the torso in opposition to the plane of rotation to add resistance to the trunk rotation muscles.
  • Place a small ball or yoga block at the medial knee and then press against it with the contralateral arm, applying isometric resistance to the trunk rotator musculature.
  • Perform the move in supine position, extending one knee and hip (on the floor) while the other hip and knee are in flexion. Rotate contralaterally.

seated twist yoga pose modification

Photos: Megan Resch

By understanding how to evaluate the involved joints and supporting musculature, yoga instructors can better modify or progress any posture to enhance its safety and effectiveness for each participant.

A Practical Way to Go Deeper

How can yoga complement the work you do with your clients? Check out the AFAA Practical Yoga Instructor Training course to find out. This online course takes yoga’s “unity” principle one step further, bringing together AFAA’s traditional methods of group ex instruction with a unique Sunrise Yoga Format™. It also gets you 7 AFAA/0.7 NASM CEUs closer to your certification renewal goal. Learn more at

Getting Started: Bilateral Evaluation as a Warmup

Before a client begins a yoga practice with you, evaluate his or her current range of motion. Look closely at shoulder, hip, trunk, knee and ankle mobility in a bilateral comparison using active range of motion. It is very common to see differences from one side of the body to the other.

A bilateral awareness of one’s body is one of the great benefits of a yoga practice and often the beginning of mindfulness training. As you perform a bilateral evaluation, explain to the participant what you are doing. This will foster development of the client’s own body awareness.

The process of evaluating joint mechanics is also a good warmup to prepare the body for a challenging yoga practice, providing information about overall ability to move into various positions. Again, by conveying what you are doing with your yoga-practicing clients, you empower them to assess their readiness and notice where their bodies may need gentleness and rest during the workout.

Since ROM is different every single day, yoga practitioners should always assess themselves before asking their bodies to perform an asana. It’s also important to consider the various physical, emotional and nutritional stresses that have a great effect on one’s daily practice. While these factors cannot necessarily be controlled ahead of time, modifications can always be made during the yoga session to address their effects on the body.

For another great resource on yoga, check this blog post out. 


Harvey-Burgess, M. 1958. The effect of twist on the mechanical properties of the intervertebral disc. Accessed Mar. 6, 2018:

Iyengar, B.K.S. 1979. Light on Yoga. New York: Schocken Books.

Kapandji, A.I. 2008. The Physiology of the Joints, Volume 3: The Spinal Column, Pelvic Girdle, and Head (6th ed.). London: Churchill Livingstone.

Levangie, P.K., & Norkin, C.C. 2011. Joint Structure and Function: A Comprehensive Analysis (5th ed.). Philadelphia: F.A. Davis Company.

Muktibodhananda, S. 1998. Hatha Yoga Pradipika (3rd ed.). Bihar, India: Yoga Publications Trust.

NASM (National Academy of Sports Medicine). 2018. NASM Essentials of Personal Fitness Training (6th ed.). Burlington, MA: Jones & Bartlett Learning.

Topics: stretching, Workout Plans

Lauren Eirk

About the Author:

LAUREN EIRK, MS, MATRX, C-IAYT, E-RYT 500, YACEP, , is founder of the Yoga Integrated Science™ Wellness Studio and a leading expert in treating muscular imbalances. When she is not teaching yoga, she can be found advocating for animal rights with the Kentucky Humane Society.

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