Table of Contents
The Human Spring Approach to Thoracic Outlet Syndrome

Chapter 3

Human Spring Engineering

Human Spring Engineering

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It should be possible to explain the laws of physics to a barmaid.

—Albert Einstein

How Does This New Model and Approach Apply to Thoracic Outlet Syndrome?

Is your body engineered as a lever mechanism or a spring mechanism?

The human body is engineered as both a lever mechanism and a spring mechanism. Understanding how these two biomechanical systems work together is essential for understanding human movement, thoracic outlet anatomy, thoracic outlet syndrome, and other painful compression disorders.

The engineering of the body's lever mechanisms has been studied for decades. However, to date, very little information has been presented to the public about how the body functions as an integrated spring mechanism or how human spring biomechanics may help maintain the spaces through which nerves and blood vessels safely pass.

In actuality, the human body functions as a living spring mechanism that allows it to recycle elastic energy, absorb and distribute impact forces, protect joints from repetitive stress, and, most important, maintain spaces and tunnels for the safe passage of blood vessels and nerves. It is vitally important that we understand how this human spring mechanism is engineered, how it works, and how spring weakness may contribute to thoracic outlet compression.

This includes inherent spring strength, spring stiffness, spring compliance, how tension on the spring is controlled, and how the body works in harmony with the established laws of physics and biomechanics. Normal muscle tension is commonly referred to as resting muscle tone, resting tone, or muscle tone.

This chapter is divided into three parts:

  • Part One—How Your Human Spring Is Engineered
  • Part Two—Spring Strength and Spring Weakness
  • Part Three—The Simple Physics of Your Human Spring
Woman watches Dr. Stoxen explain the Human Spring concept for thoracic outlet syndrome, posture, neck pain, and recovery.
Woman watches Dr. Stoxen explain the Human Spring concept for thoracic outlet syndrome, posture, neck pain, and recovery.

Part One—How Your Human Spring Is Engineered

Your human spring is engineered using bones, muscles, tendons, ligaments, fascia, cartilage, vertebral discs, and joints. The Human Spring Model indicates that the body functions as a giant integrated spring with seven interconnected floors, a 9- to 12-pound mass—the head—balanced on top of the spring, and two 10- to 15-pound masses—the arms—suspended from the upper-body spring mechanism.

The Seven Floors of Your Human Spring

Spring floor 7—The head, neck, and shoulders Spring floor 6—The spine and chest Spring floor 5—The hips Spring floor 4—The knees Spring floor 3—The ankle mortise Spring floor 2—The subtalar joint Spring floor 1—The foot arch

Body diagram shows biological springs that absorb impacts, preserve joint spaces, protect nerves, support posture, and aid recovery.
Body diagram shows biological springs that absorb impacts, preserve joint spaces, protect nerves, support posture, and aid recovery.

How does your human spring absorb impacts, recycle energy, preserve joint spaces, and help prevent the compression of blood vessels and nerves associated with thoracic outlet syndrome and other compression syndromes?

It accomplishes these functions through a variety of living biological springs.

Running skeleton graphic explains how springs help absorb impacts, recycle energy, preserve joints, and support thoracic outlet recovery.
Running skeleton graphic explains how springs help absorb impacts, recycle energy, preserve joints, and support thoracic outlet recovery.

Your Living Springs

  1. Foot arch = leaf spring
  2. Lower limb = torsion spring
  3. Menisci, cartilage, and vertebral discs = compression springs
  4. Spinal column = torsion spring
  5. Tendons = extension springs
  6. Human body = integrated torsion spring
Illustration of the Integrated Spring-Mass Model from the Human Spring Approach book on thoracic outlet syndrome.
Illustration of the Integrated Spring-Mass Model from the Human Spring Approach book on thoracic outlet syndrome.

Examples of Human Spring Engineering

The Body Is a Human Spring

The human being is a biped, which means we stand, walk, and run on two legs. The advantages of bipedal locomotion include raising the head to provide a greater field of vision for detecting danger and resources, improving communication, and freeing the non-locomotor limbs—the arms—for manipulation, reaching, lifting, carrying, defense, and combat.

Being able to stand and balance on two legs is no easy task. Human beings generally begin standing between 8 and 12 months of age. We take the ability to stand upright for granted, even though standing, walking, and running are learned motor activities developed through practice, sensory feedback, balance training, and neuromuscular coordination. Like learning to ride a bicycle, swing a golf club, or speak a language, upright posture and gait improve through trial and error and eventually become automated by the brain and nervous system.

The foot-arch bridge functions more like a flexible leaf spring that is suspended from above by muscles and tendons resembling elastic bungee cords. These spring-like tendons loop around the sides of the foot like slingshot bands and have strategic attachments to the bones of the foot. Together, they form a slingshot-style spring suspension system that supports the longitudinal and transverse arches from above.

Leg spring illustration from the Human Spring Approach Integrated Spring-Mass Model of biomechanics.
Leg spring illustration from the Human Spring Approach Integrated Spring-Mass Model of biomechanics.

When the tibialis posterior tendon tears or becomes dysfunctional, this spring suspension system can fail, allowing the arch to collapse and contributing to a condition called adult-acquired flatfoot deformity. When this happens, the body loses a significant portion of its lower-extremity spring strength, impact absorption, and elastic energy recycling capacity.

Illustration of the spring-mass model of biomechanics.
Illustration of the spring-mass model of biomechanics.

The foot has 26 bones and 33 movable joints that allow it to deform its shape when the body strikes the ground. This spreads impact forces, distributes mechanical stress, and allows the load to dissipate more safely across the entire foot rather than concentrating the force in one joint or tissue.

The three-dimensional foot also changes its shape like a flexible piece of clay, allowing it to adapt to the ground and position the leg more perpendicular to the pull of gravity. This helps maintain equilibrium, postural balance, and healthy tension throughout the lower leg so that no single area becomes excessively stressed, strained, twisted, or compressed.

At the same time, healthy joint spaces allow impact forces to be absorbed through the lower-body spring mechanism without damaging the cartilage, ligaments, tendons, bones, or joint surfaces.

That same spring elasticity travels through the ankles, knees, hips, sacroiliac joints, spinal joints, and vertebral discs. Impact forces allow the bones to approach and rebound from one another while cartilage functions as a biological compression spring. When cartilage compresses, fluid and metabolic waste products are squeezed out. When the pressure is released, the cartilage draws in oxygen, nutrients, and synovial fluid that help support tissue nourishment and joint health.

  • Spring floors 1–3: The foot arch is a spring mechanism composed of 26 bones and 33 joints arranged in a three-arch, three-dimensional design. Stretchy ligaments and flexible joints allow the foot to behave like the leaf spring of a vehicle, helping absorb impact forces and store elastic energy.
Illustration of the Integrated Spring-Mass Model from the Human Spring Approach book on thoracic outlet syndrome.
Illustration of the Integrated Spring-Mass Model from the Human Spring Approach book on thoracic outlet syndrome.
  • Spring floor 2: The arch leaf spring, or "human slingshot," is suspended by spring-suspension muscles and tendons, including the tibialis posterior, tibialis anterior, peroneus longus, and peroneus brevis. These structures function like elastic slingshot bands. The tibialis posterior and tibialis anterior support the inner portion of the spring suspension system, while the peroneus longus and peroneus brevis support the outer portion.
Leg spring illustration from the Human Spring Approach Integrated Spring-Mass Model of biomechanics.
Leg spring illustration from the Human Spring Approach Integrated Spring-Mass Model of biomechanics.

Together, these muscles and tendons stretch when the foot lands, storing elastic energy before helping spring the body forward and upward.

The slingshot-style spring suspension muscles help propel the lower leg off the ground when you take a step. The direction and efficiency of movement are influenced by the amount of stretch, resting muscle tone, elastic recoil, and strength of the muscles and tendons. They work together to spring the body away from the ground with less muscular energy expenditure.

  • Spring floor 4: The quadriceps, hamstrings, adductors, and abductors help suspend and stabilize the femur over the tibia while controlling knee stiffness, joint alignment, and impact absorption.
  • Spring floor 5: The gluteus medius, gluteus maximus, gluteus minimus, external hip rotators, and iliopsoas muscles help suspend and control the pelvis, hips, and legs from above and from the sides.

If there is an imbalance in the strength, endurance, stiffness, or resting tone of the spring-suspension muscles of the lower body, the lower extremity may collapse and lock the spring on that side. This lower-body spring dysfunction can produce compensatory tension on the opposite side of the spine, neck, and shoulder.

Sometimes this lower-body imbalance is missed by the treating doctor as a source of chronic muscle tension that prevents the scalene muscles, pectoralis minor, and other thoracic outlet muscles from releasing. If you want maximum relief from thoracic outlet syndrome symptoms, you may need to restore the strength, balance, and coordination of the entire integrated human spring from the floor upward.

The spine can twist, bend, rotate, and spring through many different configurations to accept mechanical loads, absorb impacts, and rebound from forces occurring at millions of different angles.

Think about how football players, basketball players, hockey players, rugby players, gymnasts, runners, and martial artists twist, move, jump, collide, bounce, and fall without becoming injured during most movements. This protection is partly related to the unique torsion-spring resistance, elasticity, and spring-suspension mechanics of the spine and entire human body.

Running skeleton graphic explains how springs help absorb impacts, recycle energy, preserve joints, and support thoracic outlet recovery.
Running skeleton graphic explains how springs help absorb impacts, recycle energy, preserve joints, and support thoracic outlet recovery.

Your Body Will Collide with Earth Approximately 287,401,000 Times in Your Lifetime

Running skeleton graphic explains how springs help absorb impacts, recycle energy, preserve joints, and support thoracic outlet recovery.
Running skeleton graphic explains how springs help absorb impacts, recycle energy, preserve joints, and support thoracic outlet recovery.

During an average lifetime, it is estimated that your human spring may withstand approximately 287 million ground-impact collisions from walking, running, exercise, work, recreation, and other daily activities.

Torsion Spring

The entire body functions as one large integrated torsion spring. A torsion spring can be understood by imagining a wet towel being twisted to remove the water. The towel stores increasing amounts of elastic energy as it becomes twisted. When you release it, it quickly returns toward its original shape and releases the stored energy.

For example, when you step forward with your right leg, the left foot, ankle, lower leg, thigh, pelvis, and spine must rotate and twist to allow the right leg to advance. This movement loads elastic recoil energy into the body's torsion spring. That stored elastic energy is then released to improve movement efficiency during the next step.

Illustration of the spring-mass model of biomechanics.

Compression Spring

The spinal spring is further enhanced by the vertebral discs, which function as biological compression springs. Most doctors refer to these discs as shock absorbers. However, a conventional shock absorber is designed primarily to dissipate energy rather than return it. The spine and vertebral discs can both store and return elastic energy, allowing the human body to function as a more efficient spring-mass system.

The vertebral discs load and unload impact forces during walking, running, jumping, lifting, and collisions. The spaces maintained by healthy spinal spring mechanics also allow the spinal nerve roots to pass safely through the intervertebral foramina between the vertebrae.

This may help explain why many athletes report improvements in mobility, comfort, coordination, and sports performance after chiropractic adjustments or other treatments that restore normal joint movement. These interventions may help when they improve the movement of the integrated spring rather than simply treating the body as a collection of isolated levers.

As a matter of interest, your heart also uses spring-like proteins. Elastic proteins called titin help cardiac muscle cells stretch when the heart fills with blood and recoil when the heart contracts. This elastic recoil reduces the amount of active muscular work needed during each heartbeat.

The Chest and Shoulder Spring Design

Dr. Stoxen explains how upper trapezius and levator scapula support the shoulder and help keep the thoracic outlet open.
Dr. Stoxen explains how upper trapezius and levator scapula support the shoulder and help keep the thoracic outlet open.

Your shoulder girdle attaches to the rib cage, spine, and chest primarily through muscles, fascia, and the sternoclavicular joint. The position of the shoulder depends partly on the resting muscle tone, length, strength, stiffness, and endurance of the muscles that suspend and control the shoulder girdle.

Resting tone refers to the low level of continuous muscle activity present when the muscles are not performing a strong voluntary contraction. Balanced resting muscle tone helps maintain posture and the position of the shoulder girdle over the thoracic outlet.

The average shoulder, arm, forearm, and hand may weigh approximately 10 to 15 pounds or more. This upper-extremity mass hangs from the integrated spring mechanism of the chest, spine, neck, and shoulder girdle. The collarbone connects the shoulder complex to the sternum at the sternoclavicular joint, while the remaining upper-extremity weight is suspended over the chest and rib cage by spring-like muscles positioned around the thoracic outlet.

The thoracic outlet is the passageway through which the brachial plexus, subclavian artery, and subclavian vein travel from the neck and chest into the arm. Therefore, the strength and resting tone of the shoulder-suspension muscles may directly influence the amount of space available for the neurovascular bundle.

Your shoulder is held in position by the spring stiffness, natural strength, endurance, and resting tone of several muscles. However, only a small group of muscles provides meaningful upward suspension of the shoulder girdle above the thoracic outlet tunnel. Coincidentally, exercises designed to develop these shoulder-suspension muscles are among the most neglected upper-body exercises. You will learn these exercises in Chapter 14, "Spring Training."

Illustration of normal thoracic outlet anatomy for thoracic outlet syndrome according to Dr Stoxen's Human Spring Approach to Thoracic Outlet Syndrome.
Illustration of normal thoracic outlet anatomy for thoracic outlet syndrome according to Dr Stoxen's Human Spring Approach to Thoracic Outlet Syndrome.
Illustration of thoracic outlet syndrome showing the anterior scalene and middle scalene muscles with an elevated first rib in the interscalene triangle.
Illustration of thoracic outlet syndrome showing the anterior scalene and middle scalene muscles with an elevated first rib in the interscalene triangle.

Several muscles can pull or depress the shoulder girdle downward, potentially narrowing the thoracic outlet and costoclavicular space. In contrast, the upper trapezius and levator scapulae help suspend the shoulder girdle over the thoracic outlet from above.

  • Spring floors 6–7, neck-shoulder suspension muscles: The trapezius and levator scapulae muscles contribute to the suspension, positioning, and movement of the shoulder girdle.
  • Spring floors 6–7, neck-chest muscles: The anterior scalene, middle scalene, posterior scalene, and anterior cervical muscles influence the neck, first rib, and thoracic outlet region.
  • Spring floor 6, shoulder-arm muscles: The subclavius, pectoralis minor, short head of the biceps, coracobrachialis, latissimus dorsi, lower trapezius, serratus anterior, middle scalene, posterior scalene, and pectoralis major help control tension between the chest, shoulder girdle, and arm. This muscular tension may influence compression of the thoracic outlet and thoracic tunnel.

When the pectoralis minor, short head of the biceps, coracobrachialis, latissimus dorsi, and other shoulder-depressing muscles become shortened, overactive, fatigued, or imbalanced, they can pull the shoulder girdle downward toward the rib cage. This may narrow the costoclavicular space between the clavicle and first rib and contribute to compression of the brachial plexus or subclavian blood vessels.

The rib cage is itself spring-like. Place your hands over the front of your chest and feel your ribs. Take a deep breath, then exhale gently. You can feel the rib cage expand and recoil as the chest spring helps move air into and out of the lungs.

Spring Engineering Provides Space for Structures to Pass Safely

  • Spinal nerve roots pass safely through the intervertebral foramina between the vertebrae. • The brachial plexus passes from the neck over the first rib toward the arm. • The nerves pass safely beneath the clavicle and shoulder girdle. • The subclavian artery and vein pass safely over the first rib. • The blood vessels pass safely beneath the clavicle and shoulder girdle through the thoracic outlet.

Your head weighs approximately 9 to 12 pounds, which is about the weight of a bowling ball. Mechanically, you can envision the body as a giant elastic and flexible spring with the head balanced on top and the shoulder girdles suspended from the upper portion of the spring.

How does the thoracic outlet tunnel remain open and resist injury during impacts and collisions?

  • Consider the impacts your body endures when running at full speed. When your foot strikes the ground, your 10- to 15-pound shoulders continue moving downward. When the shoulders reach the bottom of their downward movement, why do they not crush the brachial plexus, subclavian artery, and subclavian vein against the first rib?
  • If you are playing football and tackle someone with your shoulder, you would expect the impact to narrow the space between the clavicle and rib cage. Why do athletes not develop immediate thoracic outlet syndrome symptoms with every collision? A temporary brachial plexus injury during sports is sometimes called a stinger or burner.
  • Why does the thoracic outlet not narrow enough to cut off blood flow or compress the nerves when you carry a heavy purse, backpack, suitcase, or shoulder bag?
  • A forceful football tackle may expose the neck and shoulder to forces similar to those experienced during a car accident. Why is thoracic outlet syndrome commonly associated with whiplash injuries but less commonly produced by every routine impact in contact sports?

Look closely at how the neurovascular bundle passes through the thoracic outlet, which I also refer to as the thoracic tunnel. The brachial plexus and subclavian blood vessels travel from the neck and chest, over the first rib, beneath the clavicle and shoulder complex, and into the arm.

The simplest explanation for thoracic outlet compression is that the rib cage or first rib rises into the thoracic tunnel, the shoulder girdle and clavicle descend into the tunnel, or both changes occur simultaneously. In many patients with thoracic outlet syndrome, both mechanisms may contribute to narrowing of the outlet.

Now think about how professional football, hockey, rugby, and other contact-sport athletes use their shoulders and necks to tackle opponents and absorb extreme impact forces.

According to Timothy Gay, author of Football Physics: The Science of the Game, Marcus Trufant, at 5 feet 11 inches and 199 pounds, was an average-sized National Football League defensive back. Those measurements do not stand out in a league where more than 500 players weighed 300 pounds or more during the 2006 training camps. However, a defensive back's mass combined with an average 40-yard-dash speed of 4.56 seconds can generate up to 1,600 pounds of tackling force (1).

Illustration of thoracic outlet syndrome showing contracted pectoralis minor, subclavius, coracobrachialis, and biceps short head narrowing the costoclavicular and subpectoral spaces.
Illustration of thoracic outlet syndrome showing contracted pectoralis minor, subclavius, coracobrachialis, and biceps short head narrowing the costoclavicular and subpectoral spaces.

If this entire 1,600-pound force were absorbed only by the shoulder girdle, it could force the shoulder downward toward the thoracic outlet and potentially compress the nerves and blood vessels. Why does the shoulder not crash into the brachial plexus, subclavian artery, and subclavian vein with every football tackle?

The answer is spring engineering and whole-body force distribution.

The thoracic outlet remains open because the shoulder girdle is supported by a living suspension system. I call this the shoulder-chest spring-suspension system. The impact is not absorbed completely by the shoulder. Instead, the force is distributed across the integrated spring system of the feet, legs, hips, spine, rib cage, neck, and shoulders, reducing the amount of mechanical stress concentrated in the thoracic outlet.

A useful analogy is bungee jumping. A bungee cord functions as an extension spring. It extends downward, stores elastic energy as it stretches, and then recoils upward when it reaches its maximum extension.

  • You are the shoulder girdle. • The bungee cords are the upper trapezius and levator scapulae muscles. • The river below represents the brachial plexus and subclavian blood vessels. • The hard ground represents the first rib and rib cage.

If the bungee cord lacks sufficient strength, stiffness, or endurance, you may reach the river or hard ground before the spring recoils. Similarly, if the shoulder-suspension muscles are weak or fatigued, the shoulder girdle may descend toward the first rib and reduce the available space in the thoracic outlet.

The primary muscles that suspend the shoulder girdle over the thoracic outlet and chest include:

  • Upper trapezius—helps suspend and position the shoulder girdle over the chest. • Levator scapulae—helps elevate and suspend the scapula and shoulder girdle.

Now you may better understand why football players often appear to have very short necks. They develop powerful upper trapezius, levator scapulae, and neck muscles that create a strong shoulder-suspension system. Differences in neck and shoulder muscle strength may be one factor contributing to the higher reported prevalence of thoracic outlet syndrome among women.

Your Human Spring Must Be Integrated, Linked, and Coordinated

The word "integrated" means combining and coordinating separate elements into a harmonious and interrelated whole. The body is composed of different types of biological springs that are linked into one integrated spring-mass system. The head functions as a mass balanced on the upper portion of the spring, while the arms function as suspended masses attached to the shoulder girdles.

The Force That Holds Your Spring Linked When Standing or Sitting Is Called Resting Tone

Healthy muscle tone helps posture, joint alignment, thoracic outlet space, neck pain, back pain, and recovery.
Healthy muscle tone helps posture, joint alignment, thoracic outlet space, neck pain, back pain, and recovery.

In physiology, medicine, and anatomy, muscle tone—also called residual muscle tension or tonus—is the continuous, passive, partial activation of muscles or their resistance to passive stretch while at rest (2). Normal passive muscle tone helps maintain upright posture with minimal energy expenditure and allows the body to stand or sit for prolonged periods without excessive fatigue.

Your muscles and tendons link your bones together to form the human spring. While sitting or standing, a minimal amount of muscle activation is required to hold the bones and joints in alignment. This helps maintain balanced tension, preserve joint spaces, and prevent excessive strain on individual muscles, ligaments, and tendons. We will refer to this baseline muscular tension as resting muscle tone.

To reduce injury risk, muscular strength, endurance, stiffness, flexibility, and resting tone must be balanced throughout all seven floors of the human spring. If one floor is trained much more heavily than another, a spring imbalance may develop and create abnormal strain or compensation elsewhere in the body.

Resting tone also maintains tension in the upper trapezius and levator scapulae muscles, helping suspend the shoulder girdle high enough to preserve an open thoracic outlet. If these muscles become weak, fatigued, injured, or neurologically inhibited, their resting tone may become insufficient to support the shoulder. The roof of the thoracic outlet may then descend, narrowing the thoracic tunnel and increasing the risk of brachial plexus compression, subclavian vein compression, or subclavian artery compression.

We will discuss this in greater detail in Chapter 5, "The Cause of Compression," when we examine the causes of thoracic outlet syndrome.

When a patient has rounded or slouched shoulders that allow the shoulder girdles to descend toward the thoracic outlet, we recommend exercises designed to improve the strength, endurance, and resting tone of the postural and shoulder-suspension muscles. The objective is to reposition the shoulder girdle so it provides maximum space for the brachial plexus and blood vessels to pass safely through the thoracic outlet. You will learn more about these thoracic outlet syndrome exercises in Chapter 14, "Spring Training."

When you are upright, there is always a degree of internal tension and compression within the spring that helps keep the bones stacked and the joints aligned. Balanced resting tone helps maintain spaces for joints, spinal nerve roots, peripheral nerves, arteries, and veins.

Illustration of inflamed intercostal muscles associated with thoracic outlet syndrome and intercostal neuritis.
Illustration of inflamed intercostal muscles associated with thoracic outlet syndrome and intercostal neuritis.

Hooke's Law of Physics Applied to Your Human Spring

Hooke's law of elasticity, described by the English scientist Robert Hooke in 1660, states that the deformation of a spring is related to the force or load applied to it within its elastic range. In practical terms, the heavier the load placed on a spring, the more the spring deforms or compresses.

Spring strength and spring stiffness are also important. If your human spring is strong and has an appropriate degree of stiffness and muscle tone, it can tolerate heavier loads during standing, walking, running, lifting, jumping, and sports collisions.

Your body's control center—the brain and nervous system—is capable of making continuous adjustments to the tension of the human spring. These neuromuscular adjustments are similar to changing the tension of a guitar string or adjusting the suspension of a vehicle. The nervous system modifies muscle activation and tendon tension to help the body absorb and return the forces created by walking, running, jumping, and sports movements.

Illustration of the subpectoral space, costoclavicular space, and interscalene triangle in according to Dr Stoxen's Human Spring Approach to Thoracic Outlet Syndrome.
Illustration of the subpectoral space, costoclavicular space, and interscalene triangle in according to Dr Stoxen's Human Spring Approach to Thoracic Outlet Syndrome.
Tendons are shown as biological springs that store and return energy for efficient movement, posture, exercises, and recovery.
Tendons are shown as biological springs that store and return energy for efficient movement, posture, exercises, and recovery.

Your Body Springs Like a Giant Pogo Stick

The nervous system can reduce or increase spring tension depending on the task. A more compliant spring may absorb a landing more gradually, while a stiffer spring may rebound from the ground more rapidly and improve walking or running speed.

In a Japanese study, scientists attached diagnostic ultrasound equipment to the lower leg to observe what happened within the calf muscles and tendons during walking (3).

They found that the calf muscle contracted to a relatively stable length when the foot contacted the ground and remained close to that length while body weight moved across the supporting leg. The muscle appeared to function partly as a stabilizer for the thigh and upper body, helping reduce excessive wobbling during walking and running (3).

Much of the movement was produced by the tendons stretching to absorb the landing force and then recoiling to help spring the body away from the ground. Mechanical work was supplied partly through passive elastic energy storage in the tendons (4 - 5), while the active muscles provided the force needed to support the body and maintain tension on the tendon springs.

This research demonstrated that the body bounces and recoils from the ground through spring-like muscle-tendon behavior rather than relying only on muscles pushing rigid levers across the ground. This supports the concept of the human body functioning as an integrated spring-mass system.

Spring Stiffness and Spring Compliance

Hooke's law and studies of muscle-tendon behavior provide important scientific support for understanding human spring biomechanics, elastic energy storage, spring stiffness, and spring compliance.

Illustration of thoracic outlet syndrome showing contracted pectoralis minor, subclavius, coracobrachialis, and biceps short head narrowing the costoclavicular and subpectoral spaces.
Illustration of thoracic outlet syndrome showing contracted pectoralis minor, subclavius, coracobrachialis, and biceps short head narrowing the costoclavicular and subpectoral spaces.

The differences in stiffness between various springs are obvious. For example, the springs in a vehicle suspension system must be much stiffer than the spring inside a ballpoint pen.

However, it is a mistake to confuse painful joint stiffness or muscle stiffness from an injury with the mechanical stiffness of a strong, efficient, injury-resistant human spring. Painful stiffness, protective muscle guarding, and muscle spasm are different from healthy spring stiffness.

Spring Compliance

Spring compliance is the opposite of spring stiffness. Making a spring more compliant means reducing its tension so it can deform more easily and absorb impacts over a greater distance.

A compliant landing strategy during walking or running can improve impact absorption on hard surfaces. For example, when running barefoot on a hard surface, the nervous system may reduce tension within parts of the spring to create a softer and more compliant landing.

Another example sometimes discussed involves people who survive high-speed accidents while asleep, unconscious, intoxicated, or otherwise relaxed. In some cases, a more compliant body may move with the impact instead of resisting it with excessive muscular stiffness, although many other variables determine the severity of accident injuries.

Landing with an excessively loose or compliant spring, such as during a slow and fatigued jog, may reduce joint stability. When spring stiffness is insufficient, the lower extremity may wobble during landing because the muscles have not generated enough tension in the tendons to stabilize the stacked bones and joints. This wobbling gait is commonly seen in exhausted runners near the finish of a marathon.

An excessively compliant spring is also less mechanically efficient during standing, walking, and running. More muscular effort may be required to stabilize the joints, which can contribute to earlier fatigue.

Spring Stiffness

The nervous system can increase tension in the muscles and tendons to improve healthy spring stiffness without creating pathological muscle spasm. Increased spring stiffness can allow the body to recoil from the ground with greater speed, efficiency, and elastic energy return.

Appropriate muscular and tendon stiffness also improves joint stability and may help prevent injury during sudden changes in direction, landing, running, and sports collisions. Insufficient stiffness may destabilize joint motion and increase the risk of soft-tissue injury (11) (10) (9) (8) (7) (6).

In practical terms, healthy spring stiffness reduces excessive wobbling during walking and running. When we apply this concept to the neck, shoulders, and thoracic outlet, the objective is to prevent the head and shoulder girdles from wobbling or collapsing excessively during walking, running, working, or sitting at a desk.

The exercises in Chapter 14 are designed to improve the strength, endurance, and mechanical stiffness of the neck, upper back, shoulder, and thoracic outlet suspension system.

A stiffer spring can also generate greater impact forces. During running, the spring should not become excessively stiff because adequate deformation is still needed to absorb impacts. This is especially important at higher running speeds.

Coaches and athletes continually search for the ideal combination of spring compliance and spring stiffness to achieve safe, fast, efficient, and powerful performance.

What Determines Human Spring Strength?

  • Overall body stiffness • Single-joint stiffness, including foot, ankle, knee, hip, spine, neck, and shoulder stiffness • Muscle-tendon unit stiffness, such as the medial gastrocnemius and Achilles tendon working together • Individual tissue stiffness, such as Achilles tendon stiffness • Individual muscle-fiber stiffness • Cellular stiffness, because even individual cells possess measurable mechanical properties

A Weak Human Spring

  • Not strong enough to absorb and distribute impacts, increasing vulnerability to injury • Not strong enough to create sufficient stiffness for efficient movement, contributing to chronic fatigue • Not strong enough to resist fatigue, allowing the spring to collapse, drop, and lock • More vulnerable to chronic pain, degenerative changes, joint compression, nerve compression, and blood-vessel compression • Less capable of maintaining open anatomical spaces, including the thoracic outlet, intervertebral foramina, and other nerve tunnels

A Strong Human Spring

  • Capable of improving spring compliance to protect the body from steps, falls, sports collisions, automobile accidents, and occupational injuries • Capable of increasing spring stiffness to improve speed, power, balance, and movement efficiency • Capable of maintaining spring integrity under heavy lifting loads • Capable of maintaining posture and spring alignment during prolonged sitting, standing, walking, or working • Capable of maintaining adequate spaces for peripheral nerves, spinal nerve roots, arteries, and veins

Most important, the upper-body spring must have enough strength and endurance to maintain a wide thoracic outlet so that the brachial plexus, subclavian artery, and subclavian vein can pass safely.

Improving the strength of the muscles that support the human spring is an example of muscle tuning or spring tuning. Lever-based strengthening exercises can be used to improve muscle strength and create stronger spring tension. Strengthening the upper trapezius and levator scapulae may help suspend the shoulder girdle higher and preserve the thoracic outlet space.

However, exercises that isolate muscles and joints train only individual lever components. To develop a stronger, coordinated, integrated full-body spring, you must also perform exercises such as plyometrics and dynamic spring-training drills that challenge elastic recoil, balance, stiffness, and whole-body coordination.

I have included more than 30 thoracic outlet syndrome stretches and strengthening exercises, along with five important spring-training drills, in Chapter 14, "Spring Training." These exercises are designed to increase the strength of the human spring suspension system and specifically improve the support of the thoracic outlet and shoulder girdle.

Woman relaxes against a Vibeassage neck support device presented as a better option than a massage gun for neck pain and recovery.
Woman relaxes against a Vibeassage neck support device presented as a better option than a massage gun for neck pain and recovery.

Remember, muscle stiffness is not the same as spring stiffness. Painful muscle stiffness often develops after injury or when the brain senses strain and activates protective muscle guarding. We will discuss muscle spasm, protective tension, and thoracic outlet compression more extensively in Chapter 5, "The Cause of Compression."

Part Three—The Simple Physics of Your Human Spring As mentioned previously, much of the medical world has not yet learned to evaluate the body as a living, integrated spring. Traditional examinations, treatment methods, and explanations of musculoskeletal injuries are often based primarily on a lever model of biomechanics.

Consequently, it is my view that doctors may be missing important aspects of how the human body moves, absorbs impacts, stores and recycles elastic energy, preserves joint spaces, and maintains tunnels for nerves and blood vessels in a world governed by the laws of physics, nature, engineering, and biomechanics.

Science already contains laws that help explain how materials and springs respond to force. Established principles can help predict how the human body may respond to collisions, compression, tension, twisting, bending, loading, and repetitive mechanical stress.

Materials science incorporates principles of physics, chemistry, biology, and engineering. We can apply concepts from materials science to the human spring to better predict and understand what happens when the body is subjected to mechanical stress and force.

The Body Deforms Its Shape During Everyday Movement

The human spring, like all springs, must deform or change its shape to absorb impacts and adapt to different positions. Without flexibility, elasticity, and controlled deformation, the body would become vulnerable to tissue damage and structural failure.

In materials science, deformation refers to a change in the shape or size of an object. This concept also applies to the human body.

Healthy deformation occurs when the foot changes shape during a step. The flexible foot arch bends and deforms to absorb the landing impact while adapting to the ground and helping the body remain balanced against gravity. This is healthy elastic deformation when the foot returns to its original shape after leaving the ground.

Unhealthy deformation occurs when a body structure changes shape and does not fully return to its original form. Examples may include permanent joint changes, ligament damage, cartilage injury, or a disc that remains chronically displaced or bulged after an injury.

Spring Deformation

A deforming force may be applied to the human spring through stretching, compression, squeezing, bending, shearing, rotation, or twisting.

Two important forms of deformation can occur in the body:

  • Elastic deformation is temporary and generally protective. • Plastic deformation is persistent or permanent and may be damaging.

Elastic Spring Deformation

Elastic spring deformation occurs when a structure changes shape, stores energy during the deformation, and then returns to its original shape while releasing the stored energy.

The return to the original shape is important. Elastic deformation allows the human spring to absorb force, recycle energy, and avoid permanent structural damage.

This is an example of elastic deformation in the human body:

  • You walk on uneven ground, and your foot deforms to match the shape of the terrain.
  • The foot changes shape by flattening the arch and loading energy into the arch like the string of a bow. The tendons that suspend the arch stretch like the elastic bands of a slingshot.
  • Elastic energy is stored in the arch, plantar tissues, muscles, and tendons.
  • You spring away from the ground as the tendons recoil and the foot returns toward its original shape.

Elastic deformation is one way the body recycles energy, absorbs impact forces, and preserves the joints over a lifetime.

If your human spring is mobile, balanced, strong, and free from excessive muscle tension or joint restriction, it may withstand repetitive impact forces without permanently deforming.

Three objectives can then be achieved:

  • The body can tolerate millions of repetitive deformations without permanently damaging the spring.
  • Appropriate mechanical stress can stimulate the living spring to become stronger.
  • Healthy movement mechanics may help preserve mobility and reduce accelerated musculoskeletal aging.
Elastic versus plastic deformation lesson explains tissue recovery, posture, exercises, thoracic outlet syndrome, and long-term protection.
Elastic versus plastic deformation lesson explains tissue recovery, posture, exercises, thoracic outlet syndrome, and long-term protection.

Muscles and tendons behave partly like biological elastic bands. When they contract or stretch, they deform and store energy. When released, they recoil and return toward their original shape while releasing energy.

You want the spring system of your neck, spine, and shoulders to be strong and capable of elastic deformation during a car accident or sports collision. Ideally, the tissues absorb and distribute the force and then return to their pre-impact alignment without permanent injury.

For example, I was involved in a serious car accident in California several years ago. A truck struck my friend's compact car and forced it into a concrete wall. She sustained several herniated discs and experienced chronic pain for months. I did not feel a single ache. I believe this was partly because I had trained my human spring with exercises and drills designed to strengthen the spring-support system and improve injury resistance.

The vertebral discs provide another example. Every time you step, jump, or land, the discs act partly like compression springs. They load the force of the impact, deform slightly, and then return toward their original shape as the force is released.

When athletes tackle with their shoulders, the shoulder spring-suspension system allows controlled deformation of the shoulder girdle and surrounding elastic tissues. These structures help absorb and distribute the impact before allowing the shoulder to return toward its original position.

Mechanical examples of elastic deformation include a rubber band, metal spring, bungee cord, or pogo stick.

Plastic Deformation Is Harmful

Plastic deformation occurs when a structure is compressed, stretched, bent, or twisted beyond its elastic range and does not return to its original shape. The deformation becomes persistent or permanent.

This can happen instantaneously through a traumatic injury, such as a fracture, ligament tear, or severe disc injury. It can also develop gradually through millions of repetitive impacts performed with abnormal biomechanics.

For example, repeated abnormal loading of the big toe may gradually contribute to a permanently altered joint position known as a bunion or hallux valgus.

If you walk for approximately 78.74 years, your body may experience about 287,401,000 ground-impact deformations. Ideally, each step should involve controlled elastic deformation and a return toward normal alignment.

With approximately 287 million lifetime collisions with the ground, even subtle biomechanical abnormalities can produce significant cumulative stress and permanent structural change. According to the Human Spring Model, repeated plastic deformation may contribute to accelerated musculoskeletal aging.

To follow an effective anti-aging and injury-prevention lifestyle, the goal is to help the body deform elastically during steps, exercise, work, and daily movements and then return toward its original alignment rather than remaining permanently deformed.

Spring Yield

Every human spring and individual body structure has a maximum load or yield point. When the applied load exceeds this capacity, the structure may begin to deform permanently.

Everyone should theoretically come with a warning label similar to the label on a pogo stick:

"Caution: Do not exceed this amount of force or weight, or permanent deformation may occur."

At 10,000 steps per day multiplied by 365 days per year, the body experiences approximately 3,650,000 ground contacts each year.

When you buy a pogo stick, the instructions provide a maximum weight capacity. Suppose the maximum loading capacity is 300 pounds, but the user weighs 310 pounds. Each jump may exceed the spring's intended capacity, gradually bending or damaging the pogo stick.

Similarly, every human body has a maximum load capacity before tissues become injured, bent, torn, or broken. This concept is reflected in the expression, "the straw that broke the camel's back."

Athletes and coaches attempt to estimate the amount of force and deformation that can be applied to the human spring while remaining below the yield point. The goal is to create enough stress to stimulate adaptation and strengthening without causing injury.

Understanding and applying this principle is one reason certain coaches consistently produce national and world champions, while others struggle to develop elite athletes.

Illustration of inflamed intercostal muscles associated with thoracic outlet syndrome and intercostal neuritis.
Illustration of inflamed intercostal muscles associated with thoracic outlet syndrome and intercostal neuritis.

At Team Doctors®, we have managed strength, conditioning, biomechanics, and recovery programs for athletes. During the past 20 years, we have helped at least 20 local athletes become national or world champions, even though our gym is only 800 square feet.

Failure Strength

Failure strength is the amount of mechanical stress the body can tolerate before structural damage occurs. Examples of spring failure include:

  • Bone fractures • Herniated or ruptured discs • Meniscus tears • Ankle sprains • Muscle tears • Tendon avulsions • Ligament tears • Joint dislocations • Peripheral nerve injury • Vascular injury

The human spring may also be considered to have failed when the shoulder-suspension muscles can no longer prevent the shoulder girdle from falling toward the thoracic outlet and compressing the structures within the thoracic tunnel.

For some individuals, the spring-suspension muscles and tendons are not strong enough to manage the impact forces created during ordinary walking. Some people cannot stand with equal weight on both feet without the foot collapsing into an unstable position between excessive pronation and supination because their spring-suspension muscles are extremely weak.

A herniated, bulging, or slipped disc can be described as a plastic deformation of a compression spring within the spinal torsion-spring system. The disc changes shape during loading and does not fully return to its original form.

Continued mechanical compression may maintain the disc in a deformed position. Reducing compression on the spinal spring may reduce pressure on the bulging disc and relieve radiating pain, numbness, tingling, or other nerve-compression symptoms.

If you want to learn more about the Human Spring Approach to herniated discs, watch my lecture, "The Earliest Detection, Intervention and Prevention of Compression Syndromes, Thoracic Outlet Syndrome, Herniated Discs and Degenerative Joint Disease," presented at the World Congress on Anti-Aging Medicine in Mexico City, Mexico, in 2016.

Permanent structural deformity is rarely the primary cause of thoracic outlet syndrome in the patients I have examined. In my experience, most cases involve reversible muscular tension, postural collapse, first-rib elevation, shoulder depression, or other forms of functional thoracic outlet compression.

The most significant permanent deformities I have observed have sometimes resulted from surgery. Surgically removing scalene muscles or the first rib, or fusing sections of the spine with plates, screws, or rods, permanently alters the body's original spring engineering.

If you have already undergone thoracic outlet decompression surgery, first-rib resection, scalenectomy, cervical fusion, or another procedure, do not become discouraged. I have helped patients who previously underwent spinal fusion or extensive thoracic outlet surgery. Following the recommendations in this book may help you restore your remaining human spring as close to its optimal function as possible and may reduce pain and other symptoms.

A strong, well-conditioned human spring can protect the body from mechanical failure and injury, improve movement efficiency, and maintain wide spaces for nerves and blood vessels.

A weak or deconditioned human spring is less capable of protecting the body from injury. It is mechanically inefficient, contributes to earlier fatigue, and may allow the suspension systems that maintain the body's openings and tunnels to collapse.

This weakness may increase the risk of compression syndromes, including thoracic outlet syndrome, cervical radiculopathy, nerve entrapment, and herniated discs.

Conclusion—You Must Have a Strong Human Spring

I have delivered scientific presentations on biomechanics and human movement for more than 15 years. Whether I am giving a small workshop to 50 doctors in Kuala Lumpur, Malaysia, or a keynote presentation to thousands of doctors and scientists at a medical conference in the United States, the reaction to the explanation of the body as an integrated human spring is often the same.

They say, "It's about time someone explained how the body works and breaks down in a way that makes sense," and, "Don't all doctors think this way?"

I hope you enjoyed learning about your amazing human spring, the Integrated Spring-Mass Model, and how human spring biomechanics apply to thoracic outlet syndrome.

Now it is time to learn how the brain and nervous system control the tension on your human spring—and how abnormal tension may contribute to thoracic outlet compression.

Let's spring ahead to the next chapter.

Join Dr. Stoxen's live Q&A to learn how Human Spring concepts may support thoracic outlet syndrome, neck pain, and recovery.
Join Dr. Stoxen's live Q&A to learn how Human Spring concepts may support thoracic outlet syndrome, neck pain, and recovery.

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Frequently Asked Questions

What is the Human Spring?

The Human Spring is Dr. James Stoxen's biomechanical concept that describes the body as an integrated system of elastic tissues working together with the skeleton to absorb impacts, recycle elastic energy, preserve healthy joint spaces, and maintain open pathways for nerves and blood vessels.

Rather than viewing the body as only a system of rigid levers, the Human Spring recognizes that springs and levers work together to produce efficient movement, protect tissues, and reduce the risk of injury and compression disorders such as thoracic outlet syndrome. Throughout this book, you will learn how understanding the Human Spring provides a more complete explanation of human biomechanics, diagnosis, treatment, performance, and long-term recovery.

What is Human Spring Engineering?

Human Spring Engineering is Dr. James Stoxen's biomechanical framework that explains how the body's elastic tissues and skeletal levers work together to absorb impacts, recycle elastic energy, preserve healthy joint spaces, and maintain open pathways for nerves and blood vessels.

Unlike traditional lever biomechanics alone, Human Spring Engineering provides a more complete explanation for movement, injury prevention, thoracic outlet syndrome, and other compression disorders by applying the laws of physics and engineering to human movement. Throughout this book, you will learn how Human Spring Engineering forms the scientific foundation of the Integrated Spring-Mass Model, leading to more accurate diagnosis, more effective treatment, and long-term recovery.

Why is the thoracic outlet vulnerable to issues with Human Spring Engineering?

The thoracic outlet is especially vulnerable because it is a narrow passageway that depends on normal Human Spring Engineering to keep the brachial plexus, subclavian artery, and subclavian vein suspended and protected during movement. When abnormal spring tension, poor posture, injury, or altered biomechanics disrupt the Human Spring, the space within the thoracic outlet can narrow, increasing the risk of thoracic outlet syndrome and other compression disorders.

Throughout this book, you will learn why restoring normal Human Spring Engineering is essential for maintaining an open thoracic outlet and achieving long-term recovery from thoracic outlet syndrome.

What biomechanical model best explains thoracic outlet syndrome?

According to Dr. James Stoxen, the Integrated Spring-Mass Model provides the most complete biomechanical explanation for thoracic outlet syndrome because it combines lever biomechanics with Human Spring biomechanics to explain how the body absorbs impacts, recycles energy, preserves joint spaces, and maintains open pathways for nerves and blood vessels.

Unlike models based solely on rigid levers or the original spring-mass model, the Integrated Spring-Mass Model explains how abnormal spring tension can narrow the thoracic outlet, leading to compression of the brachial plexus, subclavian artery, and subclavian vein. Throughout this book, you will learn how the Integrated Spring-Mass Model provides the biomechanical foundation for understanding thoracic outlet syndrome, improving diagnosis, guiding treatment, and achieving long-term recovery.

Which tissues become compressed in thoracic outlet syndrome?

In thoracic outlet syndrome, the tissues most commonly compressed are the brachial plexus nerves, subclavian artery, and subclavian vein as they pass through the thoracic outlet between the neck and shoulder. Depending on the location and severity of the thoracic outlet compression, surrounding muscles, fascia, connective tissue, and lymphatic vessels may also become irritated or contribute to the compression.

Throughout this book, you will learn how identifying exactly which tissues become compressed in thoracic outlet syndrome is essential for making an accurate diagnosis and selecting the most effective treatment.

Which muscles contribute to thoracic outlet syndrome?

Several muscles can contribute to thoracic outlet syndrome, including the anterior scalene, middle scalene, pectoralis minor, subclavius, levator scapulae, upper trapezius, and other muscles that influence the position and stability of the neck, shoulder, clavicle, and first rib. When these muscles become tight, weak, imbalanced, or dysfunctional, they can alter Human Spring biomechanics, narrowing the thoracic outlet and increasing compression of the brachial plexus, subclavian artery, and subclavian vein.

Throughout this book, you will learn which muscles contribute to thoracic outlet syndrome, why they become dysfunctional, and how restoring normal muscle function is essential for long-term recovery.

What role do the scalene muscles play in thoracic outlet syndrome?

The scalene muscles help stabilize the neck, elevate the first rib during breathing, and maintain the normal relationship between the neck, shoulder, and thoracic outlet. When the anterior scalene or middle scalene become chronically tight, overactive, or dysfunctional, they can contribute to thoracic outlet syndrome by narrowing the space around the brachial plexus, subclavian artery, and subclavian vein.

Throughout this book, you will learn why restoring normal scalene muscle function and Human Spring biomechanics is essential for relieving thoracic outlet compression and achieving long-term recovery.

What role does the pectoralis minor play in thoracic outlet syndrome?

The pectoralis minor muscle helps stabilize and control the position of the shoulder blade, but when it becomes chronically tight or shortened, it can compress the brachial plexus, subclavian artery, and subclavian vein beneath the muscle, contributing to pectoralis minor syndrome and thoracic outlet syndrome. Abnormal tension in the pectoralis minor can also alter Human Spring biomechanics, increasing stress throughout the shoulder girdle and narrowing the pathways that protect the nerves and blood vessels.

Throughout this book, you will learn how restoring normal pectoralis minor function is an important part of relieving thoracic outlet compression and achieving long-term recovery.

What role does the subclavius muscle play in thoracic outlet syndrome?

The subclavius muscle helps stabilize the clavicle during shoulder movement, but when it becomes tight, shortened, or injured, it can reduce the space beneath the collarbone and contribute to thoracic outlet syndrome by increasing compression of the subclavian vein, subclavian artery, and brachial plexus. Because the subclavius muscle lies directly over the costoclavicular space, dysfunction of this small muscle can significantly affect Human Spring biomechanics and normal neurovascular movement.

Throughout this book, you will learn how the subclavius muscle interacts with the clavicle, first rib, and surrounding tissues, and why restoring its normal function can be an important part of treating thoracic outlet syndrome.

What role does the omohyoid muscle play in thoracic outlet syndrome?

The omohyoid muscle helps position the hyoid bone during swallowing and speech, but because it crosses the lower neck near the brachial plexus and major blood vessels, abnormal tension or anatomical variations can occasionally contribute to thoracic outlet syndrome in some individuals. Although the omohyoid muscle is a less common source of thoracic outlet compression than the scalene or pectoralis minor muscles, it can become part of a larger pattern of muscular dysfunction that alters Human Spring biomechanics and narrows the thoracic outlet.

Throughout this book, you will learn how every muscle surrounding the thoracic outlet should be evaluated to identify all potential contributors to thoracic outlet syndrome and achieve lasting recovery.

What role does the first rib play in thoracic outlet syndrome?

The first rib forms the floor of the thoracic outlet and serves as an important attachment site for the scalene muscles, making it a key structure in thoracic outlet syndrome. When the first rib is elevated, restricted, unstable, or unable to move normally with breathing and shoulder motion, it can narrow the thoracic outlet and increase compression of the brachial plexus, subclavian artery, and subclavian vein.

Throughout this book, you will learn why restoring normal first rib mobility and Human Spring biomechanics, rather than simply focusing on the rib itself, is fundamental to the successful treatment of thoracic outlet syndrome. According to Dr Stoxen the first rib is not the only rib to elevate into the thoracic outlet.

The entire rib cage can be elevated into the throracic outlet.

What role does the clavicle play in thoracic outlet syndrome?

The clavicle (collarbone) forms the roof of the costoclavicular space, one of the primary sites where thoracic outlet syndrome can develop, as the brachial plexus, subclavian artery, and subclavian vein pass between the clavicle and the first rib. Abnormal movement, poor posture, trauma, or altered Human Spring biomechanics can change the position of the clavicle, reducing the available space and increasing compression of these vital nerves and blood vessels.

Throughout this book, you will learn how restoring normal clavicle movement and shoulder mechanics is essential for relieving thoracic outlet syndrome and preventing the compression from returning.

How does first rib elevation alter neurovascular mechanics?

When the first rib becomes elevated or loses its normal mobility, it reduces the space within the thoracic outlet, increasing mechanical stress on the brachial plexus, subclavian artery, and subclavian vein as they pass between the first rib and the clavicle. This altered neurovascular mechanics can increase nerve irritation, restrict blood flow, impair normal tissue gliding, and contribute to the pain, numbness, tingling, and weakness associated with thoracic outlet syndrome.

Throughout this book, you will learn how restoring normal first rib movement and Human Spring biomechanics helps normalize neurovascular mechanics and reduce compression throughout the thoracic outlet.

How does clavicular depression contribute to thoracic outlet syndrome?

Clavicular depression lowers the collarbone toward the first rib, reducing the size of the costoclavicular space where the brachial plexus, subclavian artery, and subclavian vein travel through the thoracic outlet. This narrowing can increase neurovascular compression, especially during repetitive arm movements, poor posture, heavy backpack use, or downward shoulder loading, contributing to the symptoms of thoracic outlet syndrome.

Throughout this book, you will learn how restoring normal clavicular mechanics, shoulder stability, and Human Spring biomechanics helps relieve thoracic outlet syndrome by reducing compression within the costoclavicular space.

How does scalene muscle hypertonicity affect the brachial plexus?

Scalene muscle hypertonicity occurs when the anterior and middle scalene muscles become chronically tight or overactive, reducing the size of the interscalene triangle where the brachial plexus and subclavian artery pass through the thoracic outlet. As this space narrows, the brachial plexus can become compressed or irritated, producing the pain, numbness, tingling, weakness, and other neurological symptoms commonly seen in thoracic outlet syndrome.

Throughout this book, you will learn why correcting scalene muscle hypertonicity and restoring normal Human Spring biomechanics are essential for reducing brachial plexus compression and ach

What role does fascial tension play in thoracic outlet syndrome?

Fascial tension can contribute to thoracic outlet syndrome by restricting the normal movement and gliding of muscles, nerves, blood vessels, and connective tissues throughout the neck, shoulder, and chest. As fascial restrictions develop from injury, inflammation, repetitive strain, poor posture, or scar tissue, they can transmit abnormal forces throughout the Human Spring system, narrowing the thoracic outlet and increasing compression of the brachial plexus, subclavian artery, and subclavian vein.

Throughout this book, you will learn how restoring healthy fascial mobility and Human Spring biomechanics helps reduce thoracic outlet compression, improve tissue gliding, and support long-term recovery.

How does posture change the size of the thoracic outlet?

Poor posture can reduce the size of the thoracic outlet by altering the position of the head, neck, shoulders, clavicle, first rib, and shoulder blade, increasing stress on the brachial plexus, subclavian artery, and subclavian vein. Forward head posture, rounded shoulders, and a depressed shoulder girdle can narrow the spaces through which these nerves and blood vessels travel, while healthy alignment helps maintain normal Human Spring biomechanics and adequate neurovascular space.

Throughout this book, you will learn how correcting posture restores the size and function of the thoracic outlet, reducing compression and supporting long-term recovery from thoracic outlet syndrome.

How does movement alter thoracic outlet tunnel dimensions?

Every movement of the neck, shoulder, arm, and rib cage changes the size and shape of the thoracic outlet, causing its anatomical tunnels to continuously widen and narrow as the body moves. When normal Human Spring biomechanics are disrupted, these dynamic changes can reduce the available space for the brachial plexus, subclavian artery, and subclavian vein, increasing compression during specific arm positions or activities.

Throughout this book, you will learn how restoring healthy movement patterns helps maintain normal thoracic outlet tunnel dimensions, improve neurovascular mobility, and reduce the symptoms of thoracic outlet sy

Why is the thoracic outlet vulnerable?

The thoracic outlet is vulnerable because it is a narrow, dynamic passageway through which the brachial plexus, subclavian artery, and subclavian vein must travel while the neck, shoulders, ribs, and arms move continuously throughout the day. Even small changes in posture, muscle tension, Human Spring biomechanics, injury, inflammation, or anatomical variation can reduce the available space within the thoracic outlet, increasing the risk of neurovascular compression.

Throughout this book, you will learn why the thoracic outlet is especially vulnerable and how restoring normal biomechanics helps protect these vital nerves and blood vessels while preventing thoracic outlet syndrome

Which tissues become compressed in thoracic outlet syndrome?

In thoracic outlet syndrome, the tissues most commonly compressed are the brachial plexus nerves, subclavian artery, and subclavian vein as they pass through the thoracic outlet between the neck and shoulder. Depending on the location and severity of the compression, surrounding muscles, fascia, connective tissue, and lymphatic vessels may also become irritated or contribute to thoracic outlet syndrome by increasing pressure on these neurovascular structures.

Throughout this book, you will learn how identifying exactly which tissues become compressed in thoracic outlet syndrome is essential for making an accurate diagnosis, determining the underlying cause, and selecting the most effective treatment.

Which muscles contribute to thoracic outlet syndrome?

Several muscles can contribute to thoracic outlet syndrome, including the anterior scalene, middle scalene, pectoralis minor, subclavius, levator scapulae, upper trapezius, and other muscles that influence the position and stability of the neck, shoulder, clavicle, first rib, and shoulder blade. When these muscles become tight, weak, imbalanced, or dysfunctional, they can disrupt Human Spring biomechanics, narrow the thoracic outlet, and increase compression of the brachial plexus, subclavian artery, and subclavian vein.

Throughout this book, you will learn which muscles contribute to thoracic outlet syndrome, how they interact as a biomechanical system, and why restoring their normal function is essential for long-term recovery.

What role does fascial tension play in thoracic outlet syndrome?

Fascial tension can contribute to thoracic outlet syndrome by restricting the normal movement and gliding of muscles, nerves, blood vessels, and connective tissues throughout the neck, shoulder, and chest. As fascial restrictions develop from injury, inflammation, repetitive strain, poor posture, or scar tissue, they can transmit abnormal forces throughout the Human Spring system, narrowing the thoracic outlet and increasing compression of the brachial plexus, subclavian artery, and subclavian vein.

Throughout this book, you will learn how restoring healthy fascial mobility and Human Spring biomechanics helps reduce thoracic outlet compression, improve tissue gliding, and support long-term recovery.

Why do static imaging studies and MRIs often miss thoracic outlet syndrome?

Most MRI and other static imaging studies capture the body in a single resting position, while thoracic outlet syndrome is often a dynamic condition that develops only during specific movements, postures, or arm positions. As a result, the brachial plexus, subclavian artery, and subclavian vein may appear normal on routine imaging even though they become compressed during everyday activities.

Throughout this book, you will learn why understanding dynamic Human Spring biomechanics, rather than relying solely on static imaging studies and MRI, is essential for accurately diagnosing thoracic outlet syndrome.

Can thoracic outlet syndrome cause muscle pain in the neck and chest?

Yes. Thoracic outlet syndrome can cause muscle pain in the neck, chest, shoulder, and upper back because compression of the brachial plexus and surrounding tissues often leads to protective muscle tightening, trigger points, inflammation, and altered Human Spring biomechanics.

Muscles such as the scalenes, pectoralis minor, subclavius, levator scapulae, and upper trapezius commonly become painful as they compensate for abnormal movement and contribute to ongoing thoracic outlet syndrome. Throughout this book, you will learn why muscle pain is often both a cause and a consequence of thoracic outlet syndrome, and how restoring normal biomechanics can relieve pain and improve function.

What other symptoms and diagnostic tests are linked to thoracic outlet syndrome?

Thoracic outlet syndrome can be associated with a wide range of symptoms, including neck pain, shoulder pain, arm pain, numbness, tingling, weakness, headaches, hand swelling, coldness, color changes, and reduced grip strength. Diagnosing thoracic outlet syndrome often requires combining a detailed medical history, physical examination, provocative maneuvers, neurological and vascular testing, electrodiagnostic studies, imaging, and selected vascular studies, because no single test can confirm every case.

Throughout this book, you will learn how combining symptoms, clinical findings, and appropriate diagnostic tests provides a more accurate diagnosis of thoracic outlet syndrome than relying on any single examination or imaging study alone.

References

  1. Gay T. Football Physics: The Science of the Game. Rodale Books, Emmaus, PA; 2004.
  2. O’Sullivan SB. Examination of motor function: Motor control and motor learning. In: O’Sullivan SB, Schmitz TJ, editors. Physical Rehabilitation. 5th ed. Philadelphia, Pennsylvania: F. A. Davis Company; 2007. pp. 233–234.
  3. Fukunaga T1, Kubo K, Kawakami Y, Fukashiro S, Kanehisa H, Maganaris CN. In vivo behaviour of human muscle tendon during walking. Proc Biol Sci. 2001 Feb 7;268(1464):229-33. https://www.ncbi.nlm.nih.gov/pubmed/11217891. Full text link https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1088596/. Full text link http://rspb.royalsocietypublishing.org/content/268/1464/229.long.
  4. Heglund NC, Fedak MA, Taylor CR, Cavagna GA. Energetics and mechanics of terrestrial locomotion. IV. Total mechanical energy changes as a function of speed and body size in birds and mammals. J Exp Biol. 1982;97:57. https://www.ncbi.nlm.nih.gov/pubmed/7086351.
  5. Cavagna GA, Saibene FP, Margaria R. Mechanical work in running. J Appl Phys. 1964;19:249. http://jap.physiology.org/content/19/2/249.
  6. Wang LI. The kinetics and stiffness characteristics of the lower extremity in older adults during vertical jumping. J Sports Sci Med. 2008 Sep 1;7(3):379-86. eCollection 2008. http://www.ncbi.nlm.nih.gov/pubmed/24149906. Full text link http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3761894/.
  7. Yoon S, Tauchi K, Takamatsu K. Effect of ankle joint stiffness during eccentric phase in rebound jumps on ankle joint torque at midpoint. International Journal of Sports Medicine. 2007;28:66-71. http://www.ncbi.nlm.nih.gov/pubmed/17024641.
  8. Butler RJ1, Crowell HP 3rd, Davis IM. Lower extremity stiffness: implications for performance and injury. Clin Biomech (Bristol, Avon). 2003 Jul;18(6):511-7. http://www.ncbi.nlm.nih.gov/pubmed/12828900.
  9. Flanagan EP1, Harrison AJ. Muscle dynamics differences between legs in healthy adults. J Strength Cond Res. 2007 Feb;21(1):67-72. http://www.ncbi.nlm.nih.gov/pubmed/17313262.
  10. Granata KP, Padua DA, Wilson SE. Gender differences in active musculoskeletal stiffness. Part II. Quantification of leg stiffness during functional hopping tasks. Journal of Electromyography and Kinesiology. 2002;12:127-135. http://www.ncbi.nlm.nih.gov/pubmed/11955985.
  11. Kuitunen S1, Kyröläinen H, Avela J, Komi PV. Leg stiffness modulation during exhaustive stretch-shortening cycle exercise. Scandinavian Journal of Medicine and Science in Sports. 2007;17:67-75. http://www.ncbi.nlm.nih.gov/pubmed/17305941.

Glossary

Browse terms by letter or search the glossary.

A Adult-Acquired Flatfoot Deformity
A condition in which the foot arch progressively collapses during adulthood, often because of dysfunction or tearing of the tibialis posterior tendon. According to the chapter, this weakens the lower-extremity Human Spring, reducing impact absorption, elastic energy recycling, and overall spring strength.
A Albert Einstein
One of history's most influential physicists. The chapter opens with his quote, "It should be possible to explain the laws of physics to a barmaid," emphasizing the author's goal of making complex biomechanical concepts understandable.
A Ankle Mortise
The anatomical joint formed by the tibia, fibula, and talus. Within the Human Spring Model it represents Spring Floor 3, helping absorb impacts while maintaining lower-extremity stability.
A Anterior Cervical Muscles
Muscles located along the front of the neck that assist in supporting the head, controlling neck motion, and influencing tension within the thoracic outlet.
A Anterior Scalene Muscle
One of the three major scalene muscles. It helps stabilize the neck and elevate the first rib during breathing. Excessive tension or shortening may contribute to thoracic outlet syndrome by narrowing the passageway around the brachial plexus and subclavian artery.
A Arm Mass
In the Human Spring Model, each upper extremity is described as a suspended mass weighing approximately 10–15 pounds. The shoulder-suspension muscles support this weight while helping preserve the thoracic outlet.
A Arterial Compression
Mechanical narrowing of an artery that restricts blood flow. Within the thoracic outlet this most commonly involves the subclavian artery.
A Athletic Collision
High-impact contact experienced during sports such as football, rugby, hockey, and martial arts. The chapter uses athletic collisions to illustrate how the integrated Human Spring distributes forces throughout the body rather than concentrating them at the shoulder.
B Balance
The body's ability to remain upright while resisting gravity. The chapter explains that balance develops through practice, sensory feedback, and neuromuscular coordination, and depends upon the coordinated function of the Human Spring Mechanism.
B Baseline Muscle Tension
See Resting Muscle Tone.
B Biological Compression Spring
A living tissue that stores mechanical energy during compression and returns that energy during recoil. The chapter identifies cartilage, menisci, and vertebral discs as biological compression springs.
B Biological Spring
A living tissue or anatomical structure capable of storing and releasing elastic energy while absorbing impacts and protecting joints. The Human Spring Model describes multiple types of biological springs throughout the body.
B Biped
A human being or animal that walks upright on two legs. The chapter explains that bipedal locomotion requires a highly sophisticated integrated spring mechanism.
B Bipedal Locomotion
Walking and running on two legs. The chapter describes this as a major engineering challenge solved by the Human Spring through coordinated balance, elastic recoil, and neuromuscular control.
B Body Deformation
The temporary or permanent change in the body's shape when subjected to mechanical forces such as compression, twisting, stretching, or impact.
B Bowling Ball Analogy
The comparison used throughout the Human Spring Model describing the head as a bowling ball balanced on top of the body's integrated spring system.
B Brachial Plexus
The major nerve network traveling from the neck into the arm. The chapter repeatedly emphasizes that preserving space for the brachial plexus is a primary engineering objective of the Human Spring.
B Bungee Cord Analogy
A comparison used to explain the function of the upper trapezius and levator scapulae. Like a bungee cord, these muscles suspend the shoulder, stretch under load, store energy, and recoil to prevent excessive shoulder depression.
C Carpal Tunnel Syndrome
A compression disorder affecting the median nerve at the wrist. It is referenced as another example of a condition caused by narrowing of anatomical tunnels.
C Cartilage
A resilient connective tissue covering joint surfaces. The chapter describes cartilage as functioning like a biological compression spring, allowing joints to absorb impacts while maintaining healthy joint spaces.
C Cellular Stiffness
The measurable mechanical stiffness of individual cells. The chapter notes that Human Spring strength exists at multiple levels, including the cellular level.
C Chest Spring
The spring-like expansion and recoil of the rib cage during breathing. The chest spring contributes to respiration while participating in the body's integrated spring system.
C Chest and Shoulder Spring Design
The engineering concept describing how the shoulder girdle, rib cage, spine, muscles, and fascia suspend the upper extremities while protecting the thoracic outlet.
C Clavicle
Also known as the collarbone, the clavicle forms the roof of the costoclavicular space. Its position strongly influences the amount of space available for the brachial plexus and subclavian vessels.
C Clavicular Depression
Downward movement of the clavicle and shoulder girdle toward the first rib. Excessive clavicular depression reduces the size of the thoracic outlet and may contribute to thoracic outlet syndrome.
C Collarbone
Common name for the clavicle.
C Compression Spring
A spring that stores energy while compressed and returns that energy upon recoil. The Human Spring Model identifies vertebral discs, cartilage, and menisci as biological compression springs.
C Compliance (Spring Compliance)
The tendency of a spring to deform easily under load. Increased compliance allows greater impact absorption, whereas insufficient compliance may increase transmitted forces.
C Compression Disorder
A condition produced when nerves or blood vessels become compressed within anatomical tunnels. Thoracic outlet syndrome is presented as a major example.
C Coracobrachialis
A shoulder muscle that helps control upper-extremity position. The chapter lists it among muscles capable of contributing to downward shoulder tension and thoracic outlet compression.
C Costoclavicular Space
The anatomical space between the clavicle and the first rib through which the brachial plexus, subclavian artery, and subclavian vein pass. Narrowing of this space is one mechanism producing thoracic outlet syndrome.
C Controlled Deformation
The normal temporary deformation of biological tissues that allows safe impact absorption, elastic energy storage, and return to normal shape without injury.
C Coordination
The ability of muscles, tendons, joints, and the nervous system to work together efficiently. Proper coordination is essential for healthy Human Spring function.
C Cumulative Mechanical Stress
The gradual accumulation of microscopic mechanical loading over millions of movements throughout life. According to the chapter, cumulative stress contributes to aging, degeneration, and chronic musculoskeletal disorders when Human Spring mechanics become abnormal.
D Deformation
A change in the shape, length, or position of a material or body structure when a force is applied. In the Human Spring Model, deformation allows the body to absorb impacts, store elastic energy, and adapt to movement. Healthy deformation is temporary (elastic deformation), whereas permanent deformation (plastic deformation) may contribute to injury.
D Dynamic Spring Tension
The constantly changing amount of tension within the Human Spring Mechanism as the brain and nervous system adapt to standing, walking, running, jumping, lifting, and changing environmental demands.
E Elastic Deformation
A temporary change in shape that stores elastic energy and allows a structure to return to its original form after the load is removed. The chapter identifies elastic deformation as one of the body's primary injury-protection mechanisms.
E Elastic Energy
Mechanical energy stored when biological tissues deform during loading. This energy is later released to improve movement efficiency, speed, and power while reducing muscular effort.
E Elastic Energy Recycling
The repeated storage and reuse of elastic energy during walking, running, jumping, and athletic movement. According to the Human Spring Model, energy recycling is one of the body's primary engineering objectives.
E Elastic Recoil
The return of stretched biological tissues toward their original shape after deformation. Elastic recoil helps propel the body during walking and running while minimizing muscular work.
E Elastic Spring Deformation
A specific form of deformation in which a spring temporarily changes shape, stores energy, and then returns to its original configuration while releasing that stored energy.
E Elasticity
The ability of a tissue or material to deform under load and return to its original shape after the force is removed. Healthy elasticity allows biological springs to function efficiently without permanent damage.
E Elastic Range
The range through which a spring or biological tissue can deform and still return completely to its original shape. Exceeding this range may produce plastic deformation or tissue injury.
E Endurance
The ability of muscles and spring-support structures to maintain function over prolonged activity. The chapter repeatedly emphasizes that insufficient endurance allows the Human Spring to collapse and contributes to thoracic outlet compression.
E Engineering
The application of scientific and mechanical principles to understand how systems function. The chapter applies engineering concepts directly to the human body to explain movement, posture, and thoracic outlet syndrome.
E Engineering Principles
Fundamental concepts governing force, motion, deformation, stiffness, and energy transfer. The Human Spring Model is presented as complying with established engineering principles.
E Equilibrium
A balanced mechanical state in which opposing forces maintain stability. The Human Spring maintains equilibrium through coordinated muscle tone, posture, and spring tension.
E Extension Spring
A spring that stores energy when stretched. The chapter compares tendons to biological extension springs because they stretch under load before recoiling to propel movement.
F Failure Strength
The maximum amount of mechanical stress a tissue can tolerate before permanent injury occurs. Examples include fractures, ligament tears, muscle tears, disc herniations, and joint dislocations.
F Fascia
A continuous sheet of connective tissue that surrounds muscles, organs, nerves, and blood vessels. Within the Human Spring Model, fascia contributes to force transmission, elastic recoil, and whole-body spring integration.
F First Rib
The uppermost rib forming the floor of the thoracic outlet. The chapter explains that elevation of the first rib or the entire rib cage can contribute to thoracic outlet narrowing.
F First-Rib Elevation
Upward movement of the first rib that reduces the available space within the thoracic outlet. The author emphasizes that elevation of the entire rib cage may also contribute to compression.
F Flatfoot Deformity
See Adult-Acquired Flatfoot Deformity.
F Foot Arch
The three-dimensional arch of the foot formed by 26 bones, 33 joints, ligaments, tendons, and fascia. Within the Human Spring Model, it functions as a leaf spring that absorbs impacts, stores elastic energy, and helps propel the body forward.
F Force Distribution
The spreading of mechanical forces throughout multiple joints, muscles, tendons, and connective tissues rather than concentrating stress in one location. Whole-body force distribution is one reason athletes tolerate high-impact collisions.
F Force Transmission
The transfer of mechanical forces throughout the integrated Human Spring. Tendons, fascia, ligaments, cartilage, and bones all participate in transmitting forces during movement.
F Football Physics
A sports science concept referenced through Timothy Gay's book describing the enormous mechanical forces generated during football tackles and athletic collisions.
F Forward Propulsion
Movement of the body generated partly by the release of stored elastic energy from biological springs.
G Gluteus Maximus
The largest muscle of the buttocks. It contributes to Spring Floor 5, helping suspend and stabilize the pelvis while controlling lower-body spring mechanics.
G Gluteus Medius
A hip muscle responsible for stabilizing the pelvis during standing and walking. Weakness may contribute to collapse of the lower-body spring.
G Gluteus Minimus
A deep hip muscle assisting pelvic stabilization and coordinated lower-extremity spring function.
G Gravity
The constant downward force acting upon the human body. According to the chapter, the Human Spring evolved to function efficiently while continually resisting Earth's gravity.
G Ground-Impact Collision
The collision that occurs each time the foot contacts the ground. The chapter estimates that the average person experiences approximately 287 million such impacts during a lifetime.
G Ground Reaction Force
The force exerted by the ground against the body during walking, running, jumping, or landing. The Human Spring distributes these forces throughout the body to minimize injury.
G Guitar String Analogy
An analogy comparing the nervous system's regulation of Human Spring tension to tuning a guitar string. Increasing or decreasing tension changes spring behavior just as tightening or loosening a guitar string changes its performance.
H Hamstrings
A group of muscles located on the back of the thigh that help stabilize the knee and hip during movement. In the Human Spring Model, the hamstrings contribute to Spring Floor 4, helping control knee stiffness, joint alignment, and impact absorption.
H Head Mass
Within the Human Spring Model, the head is considered the body's primary non-spring mass, weighing approximately 9–12 pounds. It rests upon the integrated spring system and influences balance, posture, and thoracic outlet mechanics.
H Healthy Elastic Deformation
Temporary deformation of biological tissues that allows impacts to be absorbed while enabling tissues to return to their original shape without injury. Healthy elastic deformation protects joints, muscles, tendons, ligaments, and nerves from permanent damage.
H Healthy Joint Space
The normal separation between bones that allows smooth joint movement while protecting cartilage and surrounding tissues. According to the Human Spring Model, preserving healthy joint spaces is one of the body's most important engineering functions.
H Hooke's Law
A fundamental law of physics stating that the amount a spring deforms is proportional to the force applied, provided the spring remains within its elastic range. The chapter applies Hooke's Law directly to the Human Spring, explaining how biological tissues respond to mechanical loading.
H Hooke's Law of Elasticity
The original description by Robert Hooke explaining the relationship between applied force and spring deformation. The Human Spring Model uses this principle to explain how muscles, tendons, ligaments, fascia, cartilage, and joints respond during movement.
H Human Slingshot
The author's analogy describing the foot arch suspended by the tibialis posterior, tibialis anterior, peroneus longus, and peroneus brevis tendons. These tendons function like elastic slingshot bands that store and release energy during walking and running.
H Human Spring
Dr. James Stoxen's concept describing the body as an integrated system of biological springs that absorb impacts, recycle elastic energy, preserve joint spaces, and maintain safe pathways for nerves and blood vessels.
H Human Spring Engineering
The application of engineering and physics principles to explain how the body's elastic tissues and skeletal structures work together as one integrated spring system.
H Human Spring Mechanism
The complete interconnected system of muscles, tendons, ligaments, fascia, cartilage, joints, vertebral discs, and bones that collectively function as a biological spring.
H Human Spring Model
The author's expanded biomechanical model describing the body as a seven-floor integrated spring supporting the head and suspending the upper extremities while maintaining safe neurovascular passageways.
H Human Spring Suspension System
The integrated network of muscles, tendons, fascia, ligaments, and joints that suspend the body while distributing forces during standing, walking, running, jumping, and athletic activity.
H Human Spring Weakness
A reduction in the body's ability to absorb impacts, recycle energy, preserve joint spaces, and maintain open anatomical tunnels due to weakness, fatigue, imbalance, or deconditioning.
I Impact Absorption
The process by which the Human Spring distributes mechanical forces throughout the body, reducing stress on joints, muscles, nerves, and blood vessels during movement.
I Impact Distribution
The spreading of impact forces throughout the body's integrated spring system instead of concentrating them at one joint or tissue.
I Impact Force
Mechanical force generated when the body contacts the ground or another object. Human Spring Engineering is designed to absorb and redistribute these forces safely.
I Impact Resistance
The body's ability to tolerate repeated collisions without injury. According to the chapter, impact resistance depends upon spring strength, stiffness, endurance, and coordinated neuromuscular control.
I Impact Tolerance
The amount of repetitive loading the Human Spring can withstand while remaining below its yield point and avoiding permanent deformation.
I Integrated Spring
The concept that the body's different spring structures function together rather than independently. Every floor of the Human Spring influences every other floor.
I Integrated Spring-Mass Model
The biomechanical model describing the entire body as one coordinated spring system supporting the head and suspended upper extremities. Chapter 3 expands upon this model by explaining its engineering principles.
I Integrated Torsion Spring
The description of the entire body functioning as one large torsion spring, storing and releasing energy through coordinated twisting movements.
I Interconnected Floors
The seven linked levels of the Human Spring extending from the foot arch to the head and shoulders. Dysfunction at one level influences every other level.
I Intervertebral Foramina
Openings between adjacent vertebrae that allow spinal nerve roots to exit the spinal canal. The Human Spring helps preserve these openings through healthy spring mechanics.
I Intervertebral Disc
A fibrocartilaginous structure between adjacent vertebrae functioning as a biological compression spring, storing and returning energy while preserving spinal spacing.
J Joint Alignment
Proper positioning of bones within a joint. Balanced Human Spring mechanics help preserve healthy joint alignment during movement.
J Joint Compression
Reduction of joint space caused by excessive mechanical loading. The Human Spring distributes forces to reduce excessive joint compression.
J Joint Health
The condition of healthy joints maintained through proper movement, balanced spring tension, adequate nutrition, and preservation of joint spaces.
J Joint Surface
The articular surface of bones covered with cartilage. Healthy spring mechanics reduce stress placed upon joint surfaces during movement.
K Knee Stiffness
The controlled mechanical stiffness of the knee joint during movement. Appropriate stiffness contributes to Spring Floor 4, improving impact absorption and movement efficiency.
L Latissimus Dorsi
A broad muscle of the back contributing to shoulder movement and thoracic outlet mechanics. Excessive tension may contribute to downward pull on the shoulder girdle.
L Leaf Spring
A spring made of layered flexible material that bends under load and returns to its original shape. The Human Spring Model compares the foot arch to a biological leaf spring because it absorbs impacts while storing elastic energy.
L Leg Stiffness
The overall mechanical stiffness of the lower extremity during walking, running, and jumping. Appropriate leg stiffness improves impact absorption and athletic performance.
L Levator Scapulae
A neck muscle that elevates and suspends the shoulder girdle. Along with the upper trapezius, it forms one of the primary shoulder-suspension muscles preserving thoracic outlet space.
L Ligament
A band of connective tissue connecting bone to bone. Ligaments contribute to stability while functioning as components of the integrated Human Spring.
L Load Capacity
The maximum force the Human Spring can tolerate before permanent injury or deformation occurs.
L Longitudinal Arch
The major arch running along the inside of the foot. It functions as one of the body's most important biological springs during standing, walking, and running.
L Lower Extremity Spring
The integrated spring mechanism formed by the foot, ankle, knee, hip, muscles, tendons, ligaments, and fascia that absorbs impacts and propels the body forward.
L Lower Limb Torsion Spring
The concept that the lower extremity stores and releases energy through coordinated twisting movements during walking and running.
M Marathon Fatigue
The loss of spring stiffness, stability, and movement efficiency that occurs during prolonged endurance exercise. The chapter describes exhausted runners as demonstrating increased spring compliance, excessive wobbling, and reduced mechanical efficiency.
M Mass
In biomechanics, the portion of a system that is supported by springs. Within the Human Spring Model, the head functions as the primary mass, while the arms function as suspended masses attached to the shoulder girdles.
M Materials Science
A branch of science combining physics, engineering, chemistry, and biology to understand how materials respond to force, deformation, loading, fatigue, and failure. The chapter applies materials science directly to Human Spring Engineering.
M Mechanical Efficiency
The ability to perform movement while minimizing wasted energy and unnecessary muscular work. Efficient Human Spring function improves mechanical efficiency by recycling elastic energy.
M Mechanical Load
Any external or internal force applied to the body during standing, walking, running, lifting, jumping, work, or sports. The Human Spring is engineered to tolerate and distribute mechanical loads.
M Mechanical Stress
The internal forces produced within tissues when loads are applied. Excessive mechanical stress may contribute to tissue failure, joint degeneration, and compression disorders.
M Menisci
Fibrocartilaginous structures within the knee that function as biological compression springs, helping distribute loads, absorb impacts, and protect joint surfaces.
M Middle Scalene
One of the major scalene muscles influencing the position of the neck, first rib, and thoracic outlet. Excessive tension may contribute to brachial plexus compression.
M Motor Activity
Movement controlled through coordinated activation of muscles by the nervous system. Standing, walking, and running are described as learned motor activities.
M Motor Learning
The process through which the nervous system develops efficient movement through practice and repetition. The chapter explains that upright posture and gait become automated through motor learning.
M Movement Efficiency
The ability to move while minimizing muscular effort and maximizing use of stored elastic energy. One of the principal goals of Human Spring Engineering is improved movement efficiency.
M Muscle Guarding
A protective increase in muscle activity following injury. The chapter distinguishes painful muscle guarding from healthy spring stiffness.
M Muscle Spasm
An involuntary contraction of muscle commonly associated with injury or pain. The author emphasizes that muscle spasm is different from healthy spring stiffness.
M Muscle Stiffness
Resistance of muscle to stretching. The chapter distinguishes pathological muscle stiffness from the healthy mechanical stiffness of an efficient Human Spring.
M Muscle Tone
See Resting Muscle Tone.
M Muscle-Tendon Unit
The functional combination of muscle and tendon acting together during movement. Muscle-tendon units store elastic energy and regulate Human Spring stiffness.
N National Champion
An athlete who has won a national-level championship. The author cites helping numerous athletes become national champions through biomechanics, strength, conditioning, and recovery training.
N Neuromuscular Adjustment
Continuous modification of muscle activity by the nervous system to regulate Human Spring tension, stiffness, and compliance.
N Neuromuscular Coordination
The coordinated interaction between the nervous system and muscles that allows smooth, efficient movement. According to the chapter, neuromuscular coordination develops through practice and is fundamental to Human Spring function.
N Neurovascular Bundle
The combined group of nerves and blood vessels traveling together through the thoracic outlet, including the brachial plexus, subclavian artery, and subclavian vein.
N Neurovascular Mechanics
The biomechanical behavior of nerves and blood vessels during movement. The chapter explains that preserving neurovascular mechanics is one of the primary functions of Human Spring Engineering.
N Nervous System
The body's control center regulating posture, movement, balance, muscle tone, spring stiffness, spring compliance, and spring tension. The chapter identifies the nervous system as the controller of the Human Spring.
N Normal Alignment
The healthy positioning of bones, joints, muscles, and connective tissues that allows efficient Human Spring function and minimizes compression.
O Occupational Injury
An injury resulting from work-related activities or repetitive mechanical loading. According to the chapter, a strong Human Spring provides protection against occupational injuries.
O Orthopedic Plate
A rigid metal implant used to stabilize fractures or spinal segments. The chapter notes that permanent fixation changes the body's original spring engineering.
O Overactivity
Excessive muscular or neurological activity resulting in increased spring tension, abnormal stiffness, or compression.
P Passive Elastic Energy
Mechanical energy stored in tissues without active muscle shortening. Tendons store passive elastic energy during walking and running before releasing it during recoil.
P Passive Muscle Tone
See Resting Muscle Tone.
P Pectoralis Major
A large chest muscle that influences shoulder mechanics. Along with other shoulder-depressing muscles, excessive tension may contribute to thoracic outlet narrowing.
P Pectoralis Minor
A small chest muscle attaching from the ribs to the shoulder blade. When shortened or overactive, it can pull the shoulder downward and contribute to thoracic outlet compression.
P Peroneus Brevis
A muscle-tendon unit supporting the outer portion of the foot's spring suspension system. It assists in maintaining arch stability and elastic recoil.
P Peroneus Longus
A muscle-tendon unit supporting the outer portion of the foot arch. Together with the tibialis muscles, it forms part of the Human Slingshot suspension system.
P Peripheral Nerve
A nerve outside the brain and spinal cord. The Human Spring helps preserve open pathways for peripheral nerves throughout the body.
P Plastic Deformation
Permanent deformation occurring when tissues are loaded beyond their elastic capacity. Examples include herniated discs, bunions, ligament tears, and other permanent structural changes.
P Pogo Stick Analogy
An engineering analogy illustrating how springs store and release energy. The chapter compares the Human Spring to a giant pogo stick that supports the body while absorbing impacts and returning energy.
P Postural Balance
The ability to maintain upright alignment against gravity with minimal muscular effort. Balanced resting muscle tone is essential for postural balance.
P Posterior Scalene
The smallest of the three scalene muscles. It influences neck mechanics and contributes to overall tension within the thoracic outlet region.
P Protective Muscle Guarding
A reflex increase in muscle activity following injury designed to stabilize tissues. The chapter differentiates protective guarding from healthy Human Spring stiffness.
P Protective Tension
An increase in muscle tension initiated by the nervous system to protect injured tissues. Persistent protective tension may contribute to thoracic outlet compression.
P Pronation
A normal inward rolling motion of the foot during walking. Excessive pronation resulting from Human Spring weakness may contribute to instability and lower-extremity dysfunction.
P Proprioception
The body's awareness of joint position and movement. Although not named directly, the chapter discusses sensory feedback and neuromuscular coordination, which are components of proprioceptive control during standing and walking.
R Rebound
The upward or forward movement produced when the Human Spring releases stored elastic energy after absorbing an impact. Rebounding improves movement efficiency while reducing muscular effort.
R Recovery
The restoration of normal Human Spring function after injury, fatigue, or mechanical overload. According to the chapter, recovery depends on restoring spring strength, stiffness, compliance, posture, and coordinated movement.
R Residual Muscle Tension
See Resting Muscle Tone.
R Resting Muscle Tone
The low level of continuous muscle activity present even when muscles are not voluntarily contracting. Resting muscle tone maintains posture, keeps joints aligned, preserves anatomical spaces, and helps suspend the shoulder girdle above the thoracic outlet.
R Resting Tone
Another term for Resting Muscle Tone.
R Rib Cage Spring
The spring-like mechanical behavior of the rib cage during breathing and movement. Expansion and recoil of the rib cage contribute to respiration while participating in the body's integrated spring system.
R Robert Hooke
The English scientist who described Hooke's Law of Elasticity in 1660, establishing one of the fundamental laws governing spring behavior. The Human Spring Model applies Hooke's Law directly to biological tissues.
R Rounded Shoulders
A postural abnormality in which the shoulders move forward and downward. Rounded shoulders may reduce thoracic outlet space by allowing the shoulder girdle to descend toward the first rib.
S Sacroiliac Joint
The joint connecting the sacrum to the pelvis. The chapter includes the sacroiliac joints as part of the lower-body Human Spring through which impact forces travel.
S Scalene Muscles
A group of neck muscles—including the anterior, middle, and posterior scalenes—that influence the first rib, thoracic outlet, and brachial plexus. Abnormal tension within these muscles may contribute to thoracic outlet syndrome.
S Scalenectomy
A surgical procedure involving removal of one or more scalene muscles to relieve thoracic outlet compression. The author notes that such surgery permanently alters the body's original spring engineering.
S Sensory Feedback
Information received from the body's sensory receptors that helps the nervous system improve posture, balance, coordination, and Human Spring control.
S Seven Floors of the Human Spring
The seven major biomechanical levels described by the Human Spring Model:
H Head, Neck, and Shoulders
Together they form one integrated spring mechanism.
S Shoulder-Chest Spring Suspension System
The integrated muscular suspension supporting the shoulder girdle above the thoracic outlet. The chapter compares this system to a bungee cord, explaining how it distributes impact forces throughout the body.
S Shoulder Depression
Downward movement of the shoulder girdle toward the first rib. Excessive shoulder depression narrows the thoracic outlet and increases the likelihood of neurovascular compression.
S Shoulder Girdle
The bony and muscular structure supporting the upper extremity, including the clavicle, scapula, associated joints, muscles, and connective tissues. Human Spring Engineering emphasizes maintaining the shoulder girdle in an elevated, well-supported position.
S Shoulder Suspension Muscles
The muscles responsible for supporting the shoulder girdle above the thoracic outlet. The upper trapezius and levator scapulae are identified as the primary upward suspension muscles.
S Shoulder-Suspension System
The biological suspension system formed by muscles, tendons, fascia, and connective tissues that supports the weight of the upper extremity while preserving thoracic outlet space.
S Slingshot Suspension System
The spring-support system formed by the tibialis posterior, tibialis anterior, peroneus longus, and peroneus brevis tendons beneath the foot arch. These tendons function like elastic slingshot bands that store and release energy during walking and running.
S Spring Alignment
The proper alignment of all seven floors of the Human Spring, allowing efficient movement and reducing mechanical stress.
S Spring Collapse
Failure of one or more portions of the Human Spring to maintain adequate stiffness, strength, or posture, resulting in abnormal movement and increased compression.
S Spring Compliance
The ability of a spring to deform easily under load. Increased compliance improves impact absorption, whereas excessive compliance may reduce stability and movement efficiency.
S Spring Engineering
The application of engineering principles to explain how biological tissues behave as springs during movement. Human Spring Engineering extends this concept throughout the entire body.
S Spring Failure
Mechanical failure of the Human Spring resulting in injury such as fractures, ligament tears, tendon injuries, disc herniations, joint dislocations, or thoracic outlet collapse.
S Spring Floor
One of the seven interconnected biomechanical levels comprising the Human Spring. Each floor contributes to whole-body spring function.
S Spring Integrity
The ability of the Human Spring to maintain coordinated strength, stiffness, posture, and movement under mechanical loading.
S Spring Loading
Application of force that stretches or compresses biological springs before stored energy is released.
S Spring Strength
The overall capacity of the Human Spring to absorb impacts, preserve posture, maintain joint spaces, and protect nerves and blood vessels during movement.
S Spring Stiffness
The mechanical resistance of the Human Spring to deformation. Healthy spring stiffness improves movement efficiency, stability, speed, and injury resistance without causing painful muscle spasm.
S Spring Suspension Muscles
Muscles that suspend body segments while maintaining spring tension and posture. Examples include the upper trapezius, levator scapulae, tibialis posterior, and peroneus longus.
S Spring Tuning
Training designed to improve the strength, coordination, stiffness, compliance, and endurance of the Human Spring. The chapter contrasts spring tuning with isolated lever strengthening.
S Spring Weakness
Reduced spring strength, stiffness, endurance, or coordination resulting in increased fatigue, movement inefficiency, collapse of anatomical tunnels, and greater risk of injury.
S Subclavian Artery
The major artery carrying blood to the upper extremity. It passes through the thoracic outlet and may become compressed in thoracic outlet syndrome.
S Subclavian Vein
The major vein returning blood from the upper extremity. Compression of the subclavian vein contributes to venous thoracic outlet syndrome.
S Subclavius
A small muscle beneath the clavicle that stabilizes the collarbone. Dysfunction may contribute to narrowing of the costoclavicular space.
S Subtalar Joint
The joint beneath the ankle connecting the talus and calcaneus. In the Human Spring Model it represents Spring Floor 2, contributing to adaptation on uneven ground and impact absorption.
S Supination
An outward rolling motion of the foot. Excessive supination or pronation may reflect weakness or imbalance within the lower-body Human Spring.
S Suspended Mass
A body segment supported by biological springs rather than resting directly on rigid structures. Within the Human Spring Model, both upper extremities function as suspended masses.
S Synovial Fluid
The lubricating fluid within joints. Compression and recoil of cartilage during movement help circulate synovial fluid, improving joint nutrition and health.
T Team Doctors®
The organization through which the author has managed biomechanics, strength, conditioning, recovery, and performance programs for athletes, including numerous national and world champions.
T Thoracic Outlet
The anatomical passageway between the neck and shoulder through which the brachial plexus, subclavian artery, and subclavian vein travel into the arm. Preserving this space is a major objective of Human Spring Engineering.
T Thoracic Tunnel
The author's alternate name for the thoracic outlet, emphasizing its function as a dynamic tunnel for neurovascular structures.
T Tibialis Anterior
A muscle supporting the inner portion of the foot's spring suspension system. It assists the Human Slingshot in storing and releasing elastic energy.
T Tibialis Posterior
A major tendon supporting the medial foot arch. Dysfunction may result in collapse of the foot arch and reduced Human Spring strength.
T Titin
A giant elastic protein within heart muscle cells that allows cardiac muscle to stretch and recoil efficiently during each heartbeat. The chapter uses titin as an example of biological spring engineering.
T Torsion Spring
A spring that stores energy while twisting. The Human Spring Model describes the body, lower extremities, and spine as functioning mechanically like integrated torsion springs.
T Transverse Arch
One of the three arches of the foot contributing to the foot's three-dimensional spring design.
U Upper Trapezius
The primary shoulder-suspension muscle that elevates and supports the shoulder girdle above the thoracic outlet. Strengthening the upper trapezius is presented as an important component of Human Spring rehabilitation.
U Upper-Body Spring
The integrated spring system formed by the neck, shoulders, chest, spine, and shoulder girdles that supports the head and upper extremities while preserving thoracic outlet space.
V Vertebral Disc
See Intervertebral Disc.
V Vertebral Foramen
See Intervertebral Foramina.
V Vertical Loading
The downward mechanical loading placed upon the Human Spring during standing, walking, running, lifting, and jumping.
W Weak Human Spring
A Human Spring lacking adequate strength, stiffness, endurance, or coordination. The chapter associates a weak Human Spring with fatigue, joint compression, thoracic outlet narrowing, and increased injury risk.
W Whole-Body Force Distribution
The distribution of mechanical loads throughout the integrated Human Spring rather than concentrating forces at one joint or tissue. This principle explains why athletes can tolerate enormous impact forces without immediate thoracic outlet injury.
W World Champion
An athlete winning a world-level competition. The author cites helping numerous athletes achieve world champion status through Human Spring principles.
Y Yield Point
The maximum amount of force or loading a spring or biological tissue can tolerate before permanent (plastic) deformation begins. Remaining below the yield point allows tissues to recover elastically without injury. No major glossary terms beginning with Z were introduced in Chapter 3.