How Foot and Ankle Function May Improve Strength, Balance, and Longevity (Part 3)

Part 3: Improving Force Production and Movement From Head to Toe

Written by Michael Crawley, BSc, BPT, CSCS

This is the final post in our three-part series on force production and movement, moving from the head down to the point where we actually meet the ground: the foot and ankle.

Part 1 covered how tongue and jaw position influence force output and breathing. Part 2 covered the diaphragm's role in bracing, balance, and recovery. Here's a quick recap before we continue:

Jaw & Tongue (Part 1)

• Tongue roof pressure: force production

• Relaxed tongue position: improved breathing

• Jaw squeeze: force production and balance

Diaphragm & Breathing (Part 2)

• Valsalva maneuver: force production

• Proprioception: balance and stability

• Restoration and recovery: nervous system regulation

To set the scene for this post, a quote often attributed to Leonardo da Vinci: “The foot is a masterpiece of engineering and a work of art.”

That's a good starting point for looking at the anatomy and biomechanics of the foot and ankle, and how they play a role in everything from changing direction on a football pitch to reducing fall risk later in life.

Anatomy

The foot is made up of 28 bones, which together form 31 joints. An intricate, layered system of ligaments, muscles, tendons, and connective tissue allows this complex structure to provide power, stability, and flexibility all at once (Tourillon et al., 2024).

The sole of the foot has four layers of intrinsic muscles, which support the foot's strength and balance while working together with the calf muscles.

This network of tissue and bone can act in two different ways, depending on what's needed:

• As a rigid lever with stiffness: more tension, with the joints locking into place for stability

• As a compliant, flexible extension of the lower limb: less tension, with the joints opening up to absorb load

This yin-yang presentation resonates with aspects from part 1 & 2 of this series. The tongue supports both force production and relaxation. The diaphragm supports both bracing, to increase tension, and restoration, helping ease the nervous system out of a fight-or-flight response. The foot works the same way, shifting between rigid and compliant depending on the task.

The foot is also home to an extensive network of receptors and glands (Viseux, 2020). Because it's our main point of contact with the ground, and central to balance, the foot is packed with receptors that detect pressure, pain, and temperature. While specific receptors (muscle spindles and golgi tendon organs) pick up information on extent and speed of muscle stretch.

Another interesting component specific to feet, is the extremely high density of eccrine sweat glands. From an evolutionary perspective this was to help dissipate heat but also improve control through increasing friction against a surface. This hints that we are supposed to spend time in our bare feet and tap into the innate qualities which help humans have better balance and control. (See our related post, Rethinking Barefoot Shoes, for more on this).

Biomechanics

Biomechanics can get complicated quickly, so we'll keep this simple. Several actions happen at the foot and ankle that relate directly to what's happening at the knee and above. Depending on the source, this can be broken down in more or less detail. For this post, here's what we'll work with:

• Plantarflexion: the heel lifting off the ground, as in a calf raise

• Dorsiflexion: the knee travelling over the foot with the heel down, as in a knee bend

• Eversion: the sole of the foot turning outward, away from the midline of the body

• Inversion: the sole of the foot turning inward, toward the midline of the body

• Pronation: dorsiflexion and eversion combining gradually

• Supination: plantarflexion and inversion combining gradually

Moving through these positions changes where pressure and sensation are felt in the foot and ankle, depending on the task or skill being performed. For a simple way to feel these actions in relation to gait, try this step-through drill.

For the next section, the key detail to remember is pronation. Pronation involves the inside arch of the foot coming down toward the ground, coupled with internal rotation at the knee and hip above it:

Pronation = internal rotation = force production

Zooming out, all of these actions happen constantly during everyday activities, not just training. With so many moving parts working together, the receptors mentioned above are constantly updating the brain on balance, surface changes, and body position. This is where anatomy and mechanics come together to support function, and ultimately, longevity. From here, we'll look at some practical applications.

Foot Pressure and Force

At Avos Strength, this is something our clients hear often, cueing foot pressure and points of contact, whether they're squatting, hinging, or working on single-leg balance.

As covered above, pronation goes hand in hand with internal rotation and force production. In a training context, the two key points of contact are the base of the big toe and the inside of the heel.

Here's a simple way to feel both sensations at once: stand with your feet parallel and rotate your hips and torso to one side, as if looking over your shoulder. You should feel one foot flatten, with pressure increasing through the inside arch, while the other foot tents up, with pressure shifting toward the little toe side. This is also a useful drill to try barefoot, to start building awareness and sensation in the feet.

Sticking with the squat example from Part 2: say you've worked up to a heavy set and you're attempting a 3-rep max on the back squat. You've already organized your breath to create abdominal tension, and pressed your tongue to the roof of your mouth. At the bottom of the squat, you can add one more cue:

“Push the ground away with the entire foot, with a slight bias of pressure toward the inside arch”

This taps into the mechanics of pronation, and helps integrate the foot, knee, and hip when moving a heavy load.

The same idea applies to a hinge pattern like the RDL, which can meaningfully improve sensation and loading through the posterior chain. Here's a simple cue sequence to try:

1. Start with pressure predominantly through the midfoot.

2. As you complete the hinge, shift the pressure bias toward the heels.

3. Return to the start position by shifting pressure back to the midfoot.

Rotating, squatting heavy, and hinging are just three examples that have been shown above. The same principles can be applied across a wide range of exercises and variations to improve body awareness, muscle tension, and force output.

Receptors, Balance, and Stability

As covered in the anatomy section, the foot has layers of small muscles and a wide range of receptors. Unfortunately, starting in our 40s, both the number and sensitivity of these receptors tend to decline (García-Piqueras et al., 2019), alongside some atrophy of the small muscles in the foot (Menz, 2014). This is part of why we put such an emphasis on training for longevity, balance and stability work included.

The good news: there are simple exercises that can help maintain range of motion, receptor function, and muscle strength.

A good starting point is training the foot's intrinsic muscles, by challenging the big toe and other toes to work both together and independently, lifting and pressing into the ground. To add a strength component, try curling the toes against the ground to move forward in a creeping motion.

• Foot intrinsic exercise

• Foot intrinsic creep

Single-leg balance is another simple, effective option: aim to balance on one leg for a set period of time. This can be regressed using a wall for support, or progressed by adding a ball toss for perturbation. To combine intrinsic strength, balance, and stability, try a mini calf raise with the forefoot elevated on an unstable surface. A couple of examples:

• Medicine ball single-leg stability

• Single-leg heel-gap stand

You can also get creative by layering in the foot pressure concepts from the previous section, or by changing surfaces (an Airex pad, a yoga mat, or artificial turf) to create a richer sensory environment for the nerve receptors to respond to.

This matters more than it might seem. Research has shown that improving strength at the big toe can improve sprint and jump performance (Tourillon et al., 2024), and that improving intrinsic foot strength can reduce fall risk and improve proprioception in older adults (Futrell et al., 2025). Worth trying, and worth sticking with.

How to Apply This in Training

• Producing force in strength exercises: cue medial arch pressure, pushing into the floor through the base of the big toe and inside heel

• Rotating and reaching in different directions with the arms: a simple way to challenge and improve foot mechanics and mobility

• Isolated foot intrinsic exercises, done on different surfaces: improves receptor sensitivity and helps limit atrophy of the small muscles in the foot

Key Takeaways

• The foot and ankle play a direct role in force production, largely through pronation and how pressure moves through the foot

• Foot receptors and small intrinsic muscles decline with age, but simple, consistent exercises can help offset that decline

• Improving big toe and intrinsic foot strength has been linked to better sprint and jump performance, and reduced fall risk in older adults

• Like the tongue and diaphragm covered earlier in this series, the foot is often overlooked, but it's a low-effort, high-value area to train

Wrapping Up the Series

That brings this three-part series to a close. The goal throughout has been to highlight simple, practical strategies for improving performance, supporting rehabilitation, and protecting long-term health across a wide range of people, from soccer players to those managing diabetic neuropathy and reduced foot sensation.

The tongue, diaphragm, and foot are often overlooked in training, but each is a low-effort, high-value place to start. All it takes is awareness, some practice, and consistency. Hopefully, you can reap the benefits.

If you're curious how cues like these show up in your own training, whether it's foot pressure, breathing, or tongue position, that's exactly the kind of detail our coaches build into every program at Avos Strength. Feel free to reach out if you'd like to see what that looks like in practice.

References

Futrell, E., et al. (2025). The effects of intrinsic foot muscle strengthening interventions for adults over age 65: A randomized controlled trial protocol. Frontiers in Aging, 6. https://doi.org/10.3389/fragi.2025.1622232

García-Piqueras, J., et al. (2019). Ageing of the somatosensory system at the periphery: Age-related changes in cutaneous mechanoreceptors. Journal of Anatomy, 234(6), 839–852. https://doi.org/10.1111/joa.12983

Menz, H. B. (2014). Biomechanics of the ageing foot and ankle: A mini-review. Gerontology, 61(4), 381–388. https://doi.org/10.1159/000368357

Tourillon, R., et al. (2024). Human foot muscle strength and its association with sprint acceleration, cutting and jumping performance, and kinetics in high-level athletes. Journal of Sports Sciences, 42, 1–11. https://doi.org/10.1080/02640414.2024.2367365

Viseux, F. J. F. (2020). The sensory role of the sole of the foot: Review and update on clinical perspectives. Neurophysiologie Clinique, 50(1), 55–68. https://doi.org/10.1016/j.neucli.2019.12.003

How Diaphragm Function and Breathing May Improve Strength, Balance, and Recovery

Part 2: Improving Force Production and Movement From Head to Toe

Written by Michael Crawley, BSc, BPT, CSCS

Part 1 of this series looked at how jaw and tongue position influence force output and function. Part 2 turns to the diaphragm and breathing, and how they influence those same systems. As you'll see, good tongue and jaw function and good diaphragm function are closely connected, each affecting the other.

For a healthy individual, the diaphragm works through roughly 18,000 to 30,000 breaths a day. Breathing rate is largely involuntary, generated by the brainstem, but we can also consciously control it for more deliberate tasks.

Learning to influence your breathing can improve athletic performance, reduce some of the risks associated with aging, and support recovery. Before getting into that, here's a quick look at the anatomy involved.

Anatomy

The diaphragm's anatomy is complex, with connection points throughout the body. These connections include the sternum, ribs, and lumbar spine. The diaphragm also has openings that allow passage for major vessels such as the aorta and esophagus, creating a functional link between the thorax above and the abdomen below (Bordoni & Zanier, 2013).

Neural drive to the diaphragm comes from the cervical spine (C3, C4, C5), often remembered with the cue “C3-4-5 keeps the diaphragm alive.” Another key input comes from the vagus nerve, which helps regulate the depth and frequency of diaphragmatic movement, and plays an especially important role in the parasympathetic (“rest and digest”) side of breathing. These details set up the mechanisms discussed below, and help explain how to bias breathing for different outcomes.

Diaphragm, Valsalva, and Force Production

You've probably heard the cue “use your core” in gym and sport settings. It's not a particularly useful instruction, and it often gets misread as crunching the abdominals down and forward. That doesn't support what we call The Stack at Avos Strength, and it doesn't create an efficient system for force production.

As you inhale and exhale, the diaphragm's movement changes lung volume, which can be used to increase intra-abdominal pressure (IAP). This pressure allows the breath, abdominal muscles, and back muscles to work together, improving spinal stability and force production (Guo et al., 2021).

The Valsalva maneuver (VM) is a forceful exhale against a closed airway. Lifting heavy loads, or lighter loads close to failure, naturally creates a brief VM (Hackett & Chow, 2013). Combined with increased IAP, this is thought to improve spinal stability and allow for more efficient force production.

Disclaimer: Confirm with a healthcare provider that increasing training intensity or intentionally using the Valsalva maneuver is appropriate for you before adding it to your training.

A common strategy is to crunch the abdominals aggressively, which shortens the abdominal muscles and pulls the chest forward. Ironically, this limits the diaphragm's ability to descend and air to enter the thorax. To make this more concrete, here's a simple bracing sequence using the squat as an example:

1. Standing / prep: A gentle breath in, ideally through the nose.

2. Standing / prep: A slow, relaxed exhale through the mouth to generate abdominal tension.

3. Immediately pre-squat: A slight re-inhale to increase pressure against the abdominal wall.

4. Bottom position: An exhale against a closed mouth or pursed lips if the weight is heavy or fatigue is building.

For a step-by-step walkthrough, see this short video: The Myth of Bracing.

There's nuance here depending on load and volume. For example:

• At higher intensity (4 sets of 3 reps at 80% 1RM), you might reset your brace and breath every rep, or every second rep, using step 4 each time.

• At higher volume with lower intensity (3 sets of 6 reps at 70% 1RM), you might complete the first 3 to 4 reps without resetting, and without needing a forceful exhale against a closed mouth. Step 4 might only be needed on the last rep or two.

This sequence isn't necessary for every movement. Relaxed, lower-intensity work without a deliberate brace and Valsalva maneuver is a perfectly healthy strategy for exercises such as:

• Jefferson curl variations

• Spinal flow and rotational work

• Lower-intensity isometric work with continuous breathing

Now, from force production to the softer, broader effects of the diaphragm and breathing.

Further Roles and Influence

1. Proprioception, Balance, and Coordination

Proprioception (your sense of position in space), balance, and coordination are constant, everyday requirements, drawing on input from the inner ear, muscles, eyes, and nervous system. As people age, this information tends to travel less quickly and smoothly, which raises the risk of falls and related injuries. Balance exercises, walking on uneven ground, and visual exercises can all help offset that risk.

The diaphragm plays a role here too. Through its relationship with visceral fat, the diaphragm is itself a source of proprioceptive feedback (Bordoni & Zanier, 2013). Nazir et al. (2026) found that diaphragmatic breathing exercises improved balance confidence, reduced fatigue, and improved gait velocity in older adults.

The exercise used to produce that improvement was simple:

• Twice a week: 2 rounds of 6 minutes of focused diaphragmatic breathing.

• Diaphragmatic breathing: one hand on the chest, one hand on the belly button. Breathe in through the nose for 4 seconds, out through the mouth for 6 seconds.

No equipment, minimal time, and a meaningful reduction in fall risk. That's a good example of how much reach this type of training can have.

2. Restoration and Recovery

Many people are good at the hard side of training: pushing through a tough session, finishing a hard interval workout. Deliberate breathing plays an important role there, as discussed above, but recovery and downregulation matter just as much.

As mentioned in the anatomy section, the vagus nerve supplies the diaphragm and is tied to the rest-and-digest side of the nervous system. Slower, relaxed, mindful breathing after high-intensity activity can help activate the parasympathetic nervous system. Research has linked this to reductions in heart rate and respiration rate, and improvements in heart rate variability (Renaghan et al., 2023). See also Why Your Training Program Won't Work Without Sleep, Nutrition, and Recovery for more on why recovery deserves this kind of attention.

A simple way to introduce this: find a comfortable position (sitting, lying flat, or on your side) and take 10 to 20 relaxed breaths in through the nose and out through the mouth. Beyond supporting recovery, it also bookends the workout, creating a clear separation between the hard and the soft.

These are two of many ways the diaphragm and breathing influence training and daily life. There's a lot of literature on specific breathing styles (box breathing, Buteyko, and others), which can get overwhelming quickly. The simplest entry point is just adding short periods of focused, intentional breathing: relaxed in through the nose, slightly prolonged out through the mouth.

How to Apply This in Training

• Resistance training: Don't crunch the abdominals. Use a deliberate inhale-exhale to create stiffness before the movement. If appropriate, incorporate the Valsalva maneuver on higher-intensity efforts or more fatiguing higher-rep sets.

• Balance and proprioception: For older adults, add 2 sessions per week of 10 to 15 minutes of deliberate breathing practice to help offset age-related balance and fall risk.

• Restoration: Use relaxed breathing in a comfortable position after hard training to support recovery and help the body absorb the training stimulus.
  

Key Takeaways

• The diaphragm supports force production during strength training, largely through its role in generating intra-abdominal pressure.

• Deliberate breathing, not aggressive crunching, is what creates a stable, braced trunk.

• Diaphragmatic breathing can meaningfully improve balance and reduce fall risk in older adults, with just a few minutes of practice per week.

• Slow, relaxed breathing after training helps activate recovery through the parasympathetic nervous system.

• Simple, short breathing practices, done consistently, offer an outsized return relative to the effort involved.

Next Up

Moving down the body: the next post in this series will cover foot pressure and foot strength, and how they relate to force production, balance, and longevity, in the gym, in sport, and in everyday life.

References

Bordoni, B., & Zanier, E. (2013). Anatomic connections of the diaphragm: Influence of respiration on the body system. Journal of Multidisciplinary Healthcare, 6, 281–291. https://doi.org/10.2147/JMDH.S45443

Guo, J., et al. (2021). Embodiment of intra-abdominal pressure in a flexible multibody model of the trunk and the spinal unloading effects during static lifting tasks. Biomechanics and Modeling in Mechanobiology, 20(4), 1599–1626. https://doi.org/10.1007/s10237-021-01465-1

Hackett, D. A., & Chow, C.-M. (2013). The Valsalva maneuver: Its effect on intra-abdominal pressure and safety issues during resistance exercise. Journal of Strength and Conditioning Research, 27(8), 2338–2345. https://doi.org/10.1519/JSC.0b013e31827de07d

Nazir, S., et al. (2026). The effect of diaphragmatic breathing and diaphragmatic mobilization on physical performance, fear of falling, and quality of life in community-dwelling older adults: A randomized controlled trial. PLoS ONE, 21(1), e0339868.

Renaghan, E., et al. (2023). The effects of relaxation techniques following acute, high intensity football training on parasympathetic reactivation. Frontiers in Sports and Active Living, 5. https://doi.org/10.3389/fspor.2023.1267631

What Is the Stack? How Rib Cage and Pelvis Position Affect Movement

Written by Evelyn Calado, MKin, CSCS, RKin

If you've trained at Avos Strength for any length of time, you've probably heard us talk about "the stack."

Whether we're coaching a squat, a deadlift, a breathing drill, a carry, or simply standing posture, the concept comes up repeatedly.

That's because the stack is one of the foundational principles that influences how we breathe, move, stabilize, and produce force.

While it may seem like a small detail, it often has a significant impact on movement quality and performance.

What Is the Stack?

At its simplest, the stack refers to the relationship between the rib cage and the pelvis.

One way to visualize this is to think of both the rib cage and pelvis as buckets of water. When the buckets are stacked on top of one another and remain relatively level, the body is generally in a better position to manage pressure, breathe efficiently, and move well.

When either bucket tips excessively forward or backward, the relationship between the rib cage and pelvis changes. The body may then rely on compensatory strategies to create stability, manage pressure, or access movement.

While no one maintains a perfectly stacked position all the time, this analogy provides a useful framework for understanding why rib cage and pelvic position matter.

When we talk about being stacked, we're generally referring to the rib cage being positioned over the pelvis.

This doesn't mean flattening the spine, tucking the pelvis excessively, or walking around with your ribs permanently pulled down.

A stacked position still maintains the natural curves of the spine. Instead, it creates an environment where the body can effectively manage pressure, breathe efficiently, and move through available ranges of motion.

From a biomechanical perspective, stacking helps align the thoracic diaphragm and the pelvic floor. These structures form the top and bottom of a pressure system that works together with the abdominal wall to create stability throughout the trunk.

When the rib cage and pelvis are positioned well relative to one another, the body has a stronger foundation from which movement can occur.

Why We Coach the Stack

Many people think of strength, mobility, and stability as separate qualities.

In reality, they are deeply connected.

One of the primary reasons we coach the stack is because it influences the body's ability to manage pressure.

The diaphragm sits at the top of the abdominal cavity. The pelvic floor sits at the bottom. The internal obliques, transverse abdominis, and other abdominal muscles form the walls of this cylinder.

Together, these structures help regulate intra-abdominal pressure.

This pressure system plays a critical role in spinal stability, force transfer, breathing mechanics, and movement efficiency.

When pressure is managed effectively, the body is often able to access movement options more easily and distribute forces more efficiently.

A useful way to think about this is to imagine an empty aluminum pop can. Despite being made of very thin metal, an undamaged can can support a surprising amount of weight when force is distributed evenly through the structure. The moment the side of the can is dented, however, its ability to manage force drops dramatically.

While the human body is far more complex than a pop can, the analogy illustrates an important principle. When the diaphragm, abdominal wall, pelvic floor, rib cage, and pelvis work together to manage pressure, the trunk becomes remarkably efficient at transferring and resisting force.

When pressure management is compromised, the body may begin relying on compensatory strategies to create stability and movement.

The stack is not the solution to every problem, but it often provides the foundation that allows other solutions to work.

How the Stack Affects Breathing

Breathing is much more than simply getting air into the lungs.

Effective breathing requires coordination between the diaphragm, rib cage, abdominal wall, and pelvic floor. Together, these structures help create and manage pressure throughout the trunk, providing a foundation for both movement and stability.

When the rib cage and pelvis are positioned well relative to one another, the diaphragm is able to function more effectively. One reason for this is a concept known as the Zone of Apposition, which refers to the area where the diaphragm sits against the inner surface of the lower rib cage.

While the details are beyond the scope of this article, the important takeaway is that the position of the rib cage influences the position and function of the diaphragm.

When the rib cage becomes excessively elevated or flared, the diaphragm may lose some of its mechanical advantage. As a result, the body often begins relying more heavily on accessory muscles of respiration, including muscles of the neck, upper chest, and lower back.

This is one reason why individuals who struggle with breathing mechanics frequently report chronic tension through the neck, shoulders, or low back.

A complete exhalation is often one of the simplest ways to improve this relationship. Exhaling fully helps bring the rib cage down and in, allowing the diaphragm to return to a more advantageous position and creating a better starting point for the next inhale.

When the stack is present, we should see expansion occur throughout the rib cage and abdominal canister rather than exclusively through the chest, shoulders, neck, or belly.

This includes expansion through the front, sides, and back of the rib cage, as well as coordinated movement of the diaphragm and pelvic floor. This is often referred to as 360-degree expansion.

The rib cage itself is designed to move in multiple directions during respiration. As we inhale, the ribs expand and rotate to accommodate incoming air. As we exhale, they return toward a more neutral position. These movements help distribute pressure throughout the system and allow breathing to support movement rather than interfere with it.

When the stack is lost, these expansion patterns can become biased toward a particular region. Some individuals become upper-chest dominant, relying heavily on the neck and shoulders to breathe. Others primarily expand through the front of the abdomen while gaining little expansion through the sides and back of the rib cage.

Our goal is not simply to breathe into the chest or the belly. Our goal is to create balanced expansion throughout the entire canister, allowing the body to efficiently manage pressure, move well, and perform at its best.

How the Stack Affects Mobility

One of the most common misconceptions in fitness is that mobility limitations are always the result of tight muscles.

While tissue restrictions can certainly exist, many mobility limitations are influenced by joint positioning and pressure management.

The body is often reluctant to access movement that it cannot control.

When the rib cage and pelvis are poorly positioned relative to one another, the body may lose access to certain movement options.

This can influence hip internal rotation, thoracic rotation, shoulder motion, and other ranges of motion throughout the body.

As a result, an individual may feel stiff or restricted despite spending significant amounts of time stretching.

In some cases, restoring a better stack can immediately improve movement quality without any traditional stretching at all.

This doesn't mean stretching is unnecessary. Rather, it highlights the importance of addressing the underlying positional and pressure-management strategies that influence movement.

At Avos Strength, we frequently assess movement both before and after breathing and positional interventions. It is not uncommon to see meaningful changes in mobility once the body is placed in a position that allows it to better manage pressure.

How the Stack Affects Strength and Performance

Strength is ultimately the ability to produce and transfer force.

The stack plays an important role in both.

When the rib cage and pelvis are positioned effectively, the body is often better able to transfer force between the upper and lower extremities.

This can influence performance in squatting, deadlifting, pressing, carrying, sprinting, jumping, and change-of-direction activities.

The stack also influences the body's center of mass.

An individual's ability to shift, rotate, accelerate, and decelerate depends in part on where their mass is positioned and how effectively they can manage it.

When the body relies heavily on compensatory strategies, force production may become less efficient and movement options may become more limited.

This is one reason why we frequently revisit the stack during both rehabilitation and performance-focused training.

How We Help Clients Find Their Stack

For most clients, learning the stack begins with breathing.

One of the simplest ways to improve the relationship between the rib cage and pelvis is through a full exhalation. By fully exhaling, the ribs are able to move down and in, allowing the diaphragm, abdominal wall, and pelvic floor to work together more effectively.

If you'd like to try this yourself, watch our short video demonstrating how to find a stacked position from standing.

For some individuals, finding this position can be challenging while standing. In these situations, positional drills may be useful. Exercises such as a 90-90 Hip Lift can help reduce the influence of gravity and provide the body with a simpler environment in which to learn how to manage pressure and find a stacked position.

From there, we gradually integrate these concepts into movement.

This may involve developing awareness of rib cage position, pelvic position, foot pressure, breathing mechanics, and how these factors influence movement quality.

The appropriate strategy depends on the individual.

Our goal is not to force every client into the same posture. Rather, we aim to improve their ability to manage pressure, access movement options, and move efficiently.

As clients become more aware of these relationships, they often develop a greater understanding of how breathing, mobility, strength, and movement quality are interconnected.

Final Thoughts

The stack is not a magic position.

Nor is it a position that we aim to maintain at all times.

Movement is dynamic. Athletes constantly move through flexion, extension, rotation, and lateral movement depending on the demands of the task in front of them. The goal is not to remain perfectly stacked at all times or to create a rigid posture. Rather, the stack provides a foundation from which movement can occur. When the body can effectively organize the relationship between the rib cage and pelvis, it is often better able to transition into and out of different positions while maintaining efficient breathing, pressure management, and force production.

The stack simply provides a foundation.

It is a position from which the body can effectively manage pressure, breathe efficiently, and access movement options when needed.

When the rib cage and pelvis work together effectively, the body is often able to breathe better, manage pressure more efficiently, access movement options, and transfer force more effectively.

For that reason, the stack remains one of the most important concepts we teach at Avos Strength.

Whether the goal is improved mobility, greater strength, athletic performance, or simply moving and feeling better, the stack provides a foundation upon which all of those qualities can be built.

If you'd like hands-on coaching to find your own stacked position and build it into your training, our 1-on-1 Training sessions start exactly here.

The Limb Arc Model: Why You Should Train the Range of Motion You Actually Own

Written by Evelyn Calado, MKin, CSCS, RKin

If you’ve ever wondered why:

• Your knees cave in at the bottom of a squat

• Your low back extends when the weight gets heavy

• One hip always feels “stuck” at 90°

• Or mobility drills don’t seem to transfer to strength

…you’re probably running into a concept explained by the Limb Arc Model.

This model, commonly attributed to Bill Hartman, describes how rotational bias changes across ranges of joint flexion — particularly at the hip. And once you understand it, exercise selection becomes dramatically more logical.

Let’s break it down.

What Is the Limb Arc Model?

The Limb Arc Model proposes that rotational leverage changes as a joint moves through flexion.

At the hip specifically:

• Early flexion favors external rotation (ER)

• Mid-range flexion favors internal rotation (IR)

• Deep flexion returns to an external rotation bias

This is not arbitrary. It reflects changes in joint geometry, length tension relationships, and moment arms.

Most people train hip flexion as if it is one continuous quality. It is not. It is three mechanically distinct regions.

That shift matters for:

• Squats

• Deadlifts

• Split squats

• Gait mechanics

• Sport performance

• Injury risk
  

The Hip Flexion Arc Explained

Here’s the simplified breakdown:

0–60° Hip Flexion → External Rotation Bias

In early hip flexion, the joint favors:

• External rotation

• Abduction

• Supination at the foot

• Sacral counternutation

In gait, this corresponds most closely with early stance, when the heel has contacted the ground and the pelvis is relatively externally rotating as load is being accepted.

In the gym, this is the top portion of a squat or the early phase of a hinge.

External rotators and abductors have favorable leverage here.

60–100° Hip Flexion → Internal Rotation Bias

Around 90° hip flexion:

• Internal rotators and adductors have improved leverage

• Length–tension relationships favor IR

• The piriformis shifts moment arm toward IR

• The sacrum moves toward nutation

• The foot transitions toward pronation

In gait, this corresponds most closely with mid stance, when the pelvis is internally rotating on the femur and vertical ground reaction forces are highest.

In a squat, this is typically around parallel.

100°+ Hip Flexion → Returns to External Rotation Bias

As you approach deep hip flexion:

• The system transitions back toward ER

• Supination strategies often reappear

• External rotators regain leverage

This helps explain why some people feel “better” deep in a squat even if they struggle at parallel. They are returning to a range where external rotation leverage increases again.

Why Internal Rotation at 90° Matters

Most loaded bilateral lower-body exercises demand control around 60–100° hip flexion.

If internal rotation is limited in that range, common compensations show up:

• Knee valgus

• Lumbar extension

• Butt wink

• Hip shifting

• Over-pronation

• Gripping with toes

This is not always a strength problem.

It’s often a relative motion problem.

The joint is being asked to produce force in a range it does not control. When the femur is not internally rotating relative to the pelvis, the pelvis, spine, or foot moves instead.

“Train within the Range You Own”

Here’s where this becomes practical.

Owning a range means:

• You can access it

• You can control it

• You can breathe in it

• You can maintain joint relationships without compensating

If you lack IR at 90°, loading it heavily won’t fix it.

It may:

• Reinforce compensations

• Drive orientation strategies (like anterior pelvic tilt)

• Increase compressive strategies instead of restoring motion

Instead, you might need:

• Split squats that bias mid-stance

• Exercises emphasizing medial arch contact

• Internal rotation control drills

• Breathing-based repositioning work

• Heel references to restore early stance mechanics

Force production should follow motion restoration — not precede it. Ie; Restore control first. Then add load.

How This Applies to Programming

The Limb Arc Model gives you a filter for exercise selection.

The question is not whether someone “has internal rotation.”

The question is where in the arc they lose control.

If Control Breaks Down Between 0 and 60 Degrees

You will see:

• Difficulty accepting load at the top of the squat

• Poor heel contact

• Immediate external rotation gripping

• Early lumbar extension

In this case, reinforce early stance mechanics.

Use closed chain drills that emphasize heel reference and controlled external rotation.
Keep the hip in the zero to sixty degree range and teach load acceptance without extension strategies.

The goal is stable external rotation control in early hip flexion.

If Control Breaks Down Between 60 and 100 Degrees

You will see:

• Knee valgus at parallel

• Hip shift at ninety degrees

• Lumbar extension at the sticking point

• Loss of medial arch control

This is the most common presentation, and it's exactly what we cover in our post on why your knee caves inward during a squat or lunge.

Here, you bias time spent in sixty to one hundred degrees of hip flexion in closed chain.

Split squat variations are useful when organized correctly because they allow:

• Pelvis on femur relative motion

• Clear stance leg reference

• Control of hip flexion angle

• Moderate load that does not overwhelm internal rotation capacity

The key is managing support and load so that the pelvis can internally rotate on the femur without defaulting into orientation strategies such as anterior pelvic tilt or lateral shift.

This is not about making someone balance harder.

It is about placing them in the internal rotation biased window and allowing them to control it.

If Control Breaks Down Beyond 100 Degrees

You will see:

• Instability or collapse in deep squat

• Over reliance on passive structures

• Loss of tension in the bottom

In this case, gradually expose the athlete to deeper flexion under controlled conditions, restoring external rotation leverage without compensatory lumbar flexion.

Why This Model Is Powerful

The Limb Arc Model connects:

• Gait

• Breathing mechanics

• Pelvic motion

• Squat depth

• Performance

• Compensation patterns

It explains why:

• One depth feels strong and another feels unstable

• Deep squats don’t fix mid-range weakness

• “Mobility” doesn’t always transfer to strength

Because leverage changes as joint angles change.

And if you don’t own the transition between those zones, the body will compensate.

Final Takeaway

The Limb Arc Model isn’t about stretching more.

It’s about understanding that:

Rotational demands shift as joints move through flexion.

And if you load a range you don’t own, your body will borrow motion from somewhere else.

Train the range you control.

Then expand it.

That’s how you build durable strength.

Learn more about how we assess movement and build individualized programs at Avos Strength.

What Actually Happens During an Initial Assessment?

Written by Evelyn Calado, MKin, CSCS, RKin

If you’ve ever hesitated to start training because you didn’t know what to expect from that first session, you’re not alone. At Avos Strength, we treat the initial assessment as one of the most important parts of the entire training process. Not because it’s a test, or something you can pass or fail, but because it lays the foundation for everything we do moving forward. It’s how we get to know you, your goals, your movement, and how we can best support you.

Here’s what actually happens during an initial assessment with us.

It’s a 55 Minute, One-on-One Session

Most initial assessments are done in person. We also offer virtual options for remote clients. Whether we’re working with you at the gym or through a screen, the goal is the same: get a clear picture of where you’re at so we can build something that’s right for you.

It Starts With a Conversation

Before we even get moving, we sit down together and go through your intake form. And yes, it’s detailed. We ask for it to be completed at least 24 hours in advance because we actually review it before the session.

We go over:

• Your injury history and relevant medical conditions

• Sports background, hobbies, and training experience

• Your goals, both short-term and long-term

• Any current pain, discomfort, or limitations

• Your preferred training setup (in-person, hybrid, remote)

This isn’t just a checklist. It’s a conversation. We want to hear your story, understand what brings you in, and talk about how we can help. That also includes discussing which coach might be the best fit, based on your needs and our availability.

Movement Screen and Table Assessment

After the consult, we begin assessing movement.

We typically look at:

• Posture and gait

• Basic functional movements (like squats, toe touches, and rotation)

• Joint mobility and range of motion on the table

This gives us an idea of how you move in space, where you may feel limited, and what patterns we should be aware of when designing your program. For remote assessments, this part is adapted as best we can based on your space and setup.

This Is Not the Avos Performance Battery

Our initial assessment is different from the Avos Performance Battery, which is a full 90 minute performance testing session that includes a written report. This assessment is about gathering foundational information, not performance metrics. It’s the first building block in your training process, not a test.

What Happens With the Remaining Time?

Depending on how the session flows, we may use the last 10 to 20 minutes to go through some light drills, address pain points, or suggest a few exercises to get you started.

Sometimes we’ll do a bit of strength or movement testing, just enough to give us some useful data without overwhelming you on day one.

Why We Do It This Way

Your initial assessment helps us:

• Build rapport and trust

• Understand how you move

• Identify restrictions or red flags

• Gather everything we need to design a personalized program

Without this step, we’d be guessing. And that’s not how we operate. Your coach takes the time before, during, and after this session to make sure we’re starting from the right place.

How You Should Feel After

You should walk away feeling heard. You should feel supported. Ideally, you feel excited, not nervous, to start training and build something that’s going to serve you long term.

Training is a skill. It’s a habit. It’s a way of taking care of your body so you can keep doing the things you love, whether that’s playing sports, being active with your family, or just moving better every day.

Common Misconceptions We Hear

“I feel like I’m being judged.”
You’re not. There are no wrong answers in this process. If your hips move a certain way, or your shoulder is limited, that’s all information we use to help you.

“I don’t think I’m fit enough to be assessed yet.”
That’s exactly why we do assessments. You don’t need to be fit. This is about meeting you where you are and giving us a starting point to work from.

“What if I fail?”
You can’t fail. This isn’t a test. It’s a snapshot of where you’re at today.

A Structured, Individualized Approach

Everything we collect goes into your client file, not a generic template. Your program is built from the ground up based on your movement, your goals, your limitations, and your training setup.

Every Avos coach follows this system. Our junior coaches go through a structured mentorship before ever leading assessments on their own, and we continue to support them with feedback and review to maintain high standards.

There are no shortcuts. And that’s the point.

The first session isn't about being perfect. It's about getting started the right way; with a coach who sees you, listens to you, and builds something with you.

If you're ready to take the next step, explore our training options to find the approach that best fits your goals.

Rethinking Barefoot Shoes: Why They Might Not Be Right for You

Written by Evelyn Calado, MKin, CSCS, RKin

Barefoot shoes have become a go-to choice for people wanting to “fix” their feet or move more naturally. They’re light, flexible, and promote toe splay—all great things in theory. But when you look at how most of us actually live and move today, barefoot shoes may not be the solution they’re marketed to be.

Barefoot Shoes Were Designed for a Different Environment

These shoes are inspired by the way we used to move: walking on grass, dirt, sand, and other uneven terrain. Environments that challenged the foot to adapt, respond, and build strength.

But that’s not how we move now. Most people walk on flat, hard surfaces—sidewalks, tile, gym floors, concrete. Take away all the structure and cushioning, and you’re now asking your foot to do more work without the natural variability it needs to do it well.

This mismatch often leads to increased strain on the feet, knees, and hips.

Why Feeling the Ground Isn’t Always Enough

A common argument for barefoot shoes is “feel the ground.” But without something to push into, that sensation can become meaningless—or worse, problematic.

Your foot is meant to roll in, absorb force, and push off. When a shoe doesn’t give you any structure to push into, your body can’t organize movement efficiently. That can lead to things like:

• Flat, collapsed arches

• Overworking small foot muscles

• Tight calves and ankles

• Poor balance and control during walking or training

What’s Good About Barefoot Shoes (And What’s Missing)

To be clear, barefoot shoes do some things well:

• Wide toe boxes let your toes spread naturally

• Thin soles improve sensory feedback

• Zero-drop heels encourage a more upright posture

But on consistently flat, hard ground, these same features can become stressors. They remove too much structure—leaving your body with no support to work with. It’s not that they’re bad, but they aren’t ideal for most people living modern, indoor lives.

What to Look for in a Shoe That Supports You

Instead of going fully minimal, consider footwear that strikes a better balance between freedom and structure. A well-designed shoe should:

✅ Have a Firm Heel

Helps with stability during walking and lifting by anchoring the back of your foot.

✅ Be Flexible at the Toes

Let your big toe extend so you can push off properly during movement.

✅ Offer Moderate Arch Support

Just enough to guide motion—not restrict it. Especially important for those with flat feet or instability.

✅ Include a Slight Heel Drop (4–8 mm)

This small lift can take pressure off the calves and improve overall gait mechanics.

✅ Provide Cushion for Flat Surfaces

Some padding helps absorb repetitive impact from walking and training on hard floors all day.

Note: I’m talking here about everyday shoes—the ones you wear to walk, run errands, train, or do light accessory work. For heavy, bilateral lifts like deadlifts, I’ll still lift barefoot or in minimalist shoes. The shoes I recommend above can be versatile enough to train in, but not ideal for max-effort strength work. It all depends on the context, and at the end of the day what works best for you.

The Bottom Line

Barefoot shoes can be useful—in the right environment, and for the right person. But for most people training, walking, and living on hard, flat surfaces, they often cause more problems than they solve.

A good shoe doesn’t just let you feel the ground—it gives you something to push into. It should support how your body moves and make your life easier, not harder.