The Theory
Standard vs. Spiral
The Standard Model
Most of us flatten the bones of our hands and feet into two-dimensional levers as children, and use our ankles and wrists like simple hinges throughout our lives. The theory behind this prevailing model of biomechanics, here called the Standard Model for reference, is summarized below. A more detailed introduction can be found in The Inward Spiral, available for download.
The Spiral Model
An alternative to the Standard Model is introduced below. The Spiral Model proposes that the hands and feet form dynamic, three-dimensional spiral structures that rotate around a central axis when they do work. The key differences and similarities between the two models are presented looking in turn at the feet, then at gait, and finally at the hands.
The Spiral Model
An alternative to the Standard Model is introduced below. The Spiral Model proposes that the hands and feet form dynamic, three-dimensional spiral structures that rotate around a central axis when they do work. The key differences and similarities between the two models are presented looking in turn at the feet, then at gait, and finally at the hands.
Standard
Under the Standard Model, the feet are flattened and placed sole-down on the ground. Early in development, the ankles are fixed in neutral position – not too pronated or too supinated – and from then on function like oblique hinges.
Figure 1. Standard Model view of the foot from above, with the position of the underdeveloped rotational axis indicated.
Spiral
Under the Spiral Model, all 26 bones of each foot form a dynamic, three-dimensional spiral that rotates around a central axis that runs from heel to big toe. With every step, the foot rolls inward around this axis like a cresting wave.
Figure 2. Spiral Model of the foot showing the spiral structure and rotational axis of a fully developed foot.
Spiral
Under the Spiral Model, all 26 bones of each foot form a dynamic, three-dimensional spiral that rotates around a central axis that runs from heel to big toe. With every step, the foot rolls inward around this axis like a cresting wave.
Figure 2. Spiral Model of the foot showing the spiral structure and rotational axis of a fully developed foot.
Standard
Under the Standard Model, the foot is organized around a set of arches. The inner arch does most of the useful work, compressing to store energy and recoiling to release it again. The arch stiffens the foot at the end of each step so it can be used as a lever, pushing down and back to propel the body’s mass forward.
Figure 3. The arches of the foot from below. The inner – or medial longitudinal – arch is the key to the foot’s functioning.
Spiral
The foot’s close-knit spiral form can exploit torsion forces across the rotational axis, creating a dynamic spring qualitatively different from and far more effective than the passive compression forces utilized by the arches under the Standard Model.
Figure 4. The bones of each foot form a single twist of a 3D log spiral, which the foot’s internal muscles can manipulate to produce and control torsion forces.
Spiral
The foot’s close-knit spiral form can exploit torsion forces across the rotational axis, creating a dynamic spring qualitatively different from and far more effective than the passive compression forces utilized by the arches under the Standard Model.
Figure 4. The bones of each foot form a single twist of a 3D log spiral, which the foot’s internal muscles can manipulate to produce and control torsion forces.
Standard
No general guidance exists for foot development. Under the Standard Model, development is left largely to trial and error, with intervention indicated in cases of extreme pronation or supination to reduce the risk of chronic conditions later on.
Figure 5. Foot classification showing high (supinated), neutral, and low (pronated) inner arch.
Spiral
The Spiral Model holds that the human body begins its physical development in a slack or “unwound” state. Using rotational symmetry, the Counterspiral mechanism slowly repositions the bones of the feet into their spiral structures, and then stretches muscle and connective tissue over the resulting framework, effectively winding the lower body.
Figure 6. The Counterspiral mechanism is formed by the countervailing rotation of the spiral frameworks of the feet when they are rolled inward against each other at the body’s midline (right) after first being fully clenched, inverted, and abducted (left).
Spiral
The Spiral Model holds that the human body begins its physical development in a slack or “unwound” state. Using rotational symmetry, the Counterspiral mechanism slowly repositions the bones of the feet into their spiral structures, and then stretches muscle and connective tissue over the resulting framework, effectively winding the lower body.
Figure 6. The Counterspiral mechanism is formed by the countervailing rotation of the spiral frameworks of the feet when they are rolled inward against each other at the body’s midline (right) after first being fully clenched, inverted, and abducted (left).
Spiral
The Counterspiral mechanism is engaged by inverting, clenching, and abducting the feet in turn, and then rotating them against each other at the body’s midline. Standing, sitting, kneeling, and walking variations of the winding mechanism all rely on the same four movements of the feet.
Figure 7. To wind the lower body, the feet cycle through the motions of inversion, clenching, abduction, and medial rotation in any of several variations, including kneeling (left) and walking (right).
Spiral
The Counterspiral mechanism is engaged by inverting, clenching, and abducting the feet in turn, and then rotating them against each other at the body’s midline. Standing, sitting, kneeling, and walking variations of the winding mechanism all rely on the same four movements of the feet.
Figure 7. To wind the lower body, the feet cycle through the motions of inversion, clenching, abduction, and medial rotation in any of several variations, including kneeling (left) and walking (right).
Standard
The Standard Model conceives of the lower body as a set of conjoined pendulums. During each step, the swing leg functions like a simple pendulum, a device renowned for its efficiency, while the stance leg functions like an inverted pendulum.
Figure 8. An inverted pendulum is used to represent the stance leg, while a simple pendulum represents the swing leg in the Standard Model of biomechanics.
Spiral
In contrast to the conjoined pendulums of the Standard Model, which pass the body’s weight from leg to leg between steps, under the Spiral Model the entire lower body functions as a single, integrated mechanism. The cycling of the feet translates to rotation of the hips via a linked series of virtual hubs and axles, emulating the mechanics of a wheel.
Figure 9. The entire lower body functions as an integrated mechanism to emulate the mechanics of a single wheel in the Spiral Model of biomechanics.
Spiral
In contrast to the conjoined pendulums of the Standard Model, which pass the body’s weight from leg to leg between steps, under the Spiral Model the entire lower body functions as a single, integrated mechanism. The cycling of the feet translates to rotation of the hips via a linked series of virtual hubs and axles, emulating the mechanics of a wheel.
Figure 9. The entire lower body functions as an integrated mechanism to emulate the mechanics of a single wheel in the Spiral Model of biomechanics.
Standard
To produce forward motion under the Standard Model, the muscles and joints of the lower body coordinate to push the feet down and back into the ground in order to propel the body’s mass forward.
Figure 10. The axes of the ankle complex, with reference to the sole of the foot. Under the Standard Model, plantarflexion provides most of the impetus for forward motion.
Spiral
To produce forward motion under the Spiral Model, the stance foot pushes laterally while the swing heel abducts, creating a couple moment that drives the swing hip’s rotation around the midline and positions the swing foot for the next step. The body’s center of mass advances in a smooth, continuous motion while the legs cycle beneath it.
Figure 11. The torque produced by the concurrent medial roll of the stance foot and lateral abduction of the swing foot (left) is translated to the hips by a series of virtual axles and hubs operated by the bands of connective tissue and muscle that run the length of the legs (right).
Spiral
To produce forward motion under the Spiral Model, the stance foot pushes laterally while the swing heel abducts, creating a couple moment that drives the swing hip’s rotation around the midline and positions the swing foot for the next step. The body’s center of mass advances in a smooth, continuous motion while the legs cycle beneath it.
Figure 11. The torque produced by the concurrent medial roll of the stance foot and lateral abduction of the swing foot (left) is translated to the hips by a series of virtual axles and hubs operated by the bands of connective tissue and muscle that run the length of the legs (right).
Standard
To produce forward motion under the Standard Model, the muscles and joints of the lower body coordinate to push the feet down and back into the ground in order to propel the body’s mass forward.
Figure 12. Human gait is far less efficient in practice than predicted by the pendulum model. This inefficiency stems from the need to redirect the body’s mass between steps, which requires significant work.
Spiral
The Spiral Model represents human gait in its most efficient form. The battle against gravity to achieve forward motion and the wasteful transfer of mass between legs that must take place with each step – the costliest elements of the Standard Model – are both avoided as the application of lateral force drives cyclical gait.
Figure 13. Fully developed feet can engage the Spiral Model’s running gait (seen here from above). The swing foot clenches, inverts, and abducts (B), making contact with the ground behind the body’s center of mass at the foot’s vertical and mediolateral pivot between the 3rd and 4th toenails (C). As the stance foot, it then rolls medially (A) across the inverted toenails in sequence from 3rd to big toe, driving the swing foot into position ahead on the extended midline.
Spiral
The Spiral Model represents human gait in its most efficient form. The battle against gravity to achieve forward motion and the wasteful transfer of mass between legs that must take place with each step – the costliest elements of the Standard Model – are both avoided as the application of lateral force drives cyclical gait.
Figure 13. Fully developed feet can engage the Spiral Model’s running gait (seen here from above). The swing foot clenches, inverts, and abducts (B), making contact with the ground behind the body’s center of mass at the foot’s vertical and mediolateral pivot between the 3rd and 4th toenails (C). As the stance foot, it then rolls medially (A) across the inverted toenails in sequence from 3rd to big toe, driving the swing foot into position ahead on the extended midline.
Standard
According to the Standard Model, the hands and feet are functionally different, though they do have some similarities: they share the same basic skeletal plan, and like the feet the hands are flattened and placed palm-down when used in a load-bearing capacity. In addition, the hands have arches that mediate between mobility and stability and wrists that function like oblique hinges.
Figure 14. Right hand, palm side view, splayed for placement under the Standard Model, with the position of the underdeveloped rotational axis indicated.
Spiral
Under the Spiral Model, the basic functioning of the hands parallels that of the feet. The hands similarly form dynamic three-dimensional spirals that rotate around a central axis, running from outer wrist to inner thumb. This spiral construction is the key to both the load-bearing and tool-use functions of the hands.
Figure 15. The hands’ spiral construction is more self-evident than the feet’s. When a fully developed hand grips a stick, the spiral tracks the points of contact indicated with red ovals. It anchors at the pisiform bone in the wrist, revolves through the space between the 4th and 3rd fingernails, and follows the transverse arch behind the stick around to the thumb.
Spiral
Under the Spiral Model, the basic functioning of the hands parallels that of the feet. The hands similarly form dynamic three-dimensional spirals that rotate around a central axis, running from outer wrist to inner thumb. This spiral construction is the key to both the load-bearing and tool-use functions of the hands.
Figure 15. The hands’ spiral construction is more self-evident than the feet’s. When a fully developed hand grips a stick, the spiral tracks the points of contact indicated with red ovals. It anchors at the pisiform bone in the wrist, revolves through the space between the 4th and 3rd fingernails, and follows the transverse arch behind the stick around to the thumb.
Standard
The Standard hand is capable of performing a remarkable variety of actions, from supporting the body’s weight against the ground to playing the piano. The most frequent daily use is simply to grasp objects. A number of different classification systems exist for over 30 identified grip types, but most fall into either the power or precision grip categories.
Figure 16. Taxonomy of grasps classified and depicted according to thumb position, hand and finger configuration, and grouped into power, precision, and intermediate grips.
Spiral
Under the Spiral Model, when bearing load the hands are first clenched, inverted, and abducted to position the outer wrists beneath the shoulder joints. The outer edges make contact with the ground, and each hand rolls inward across its transverse arch from pinky to index finger while the thumb simultaneously rotates under the wrist, forming a stable three-dimensional spiral structure.
Figure 17. Hand placed for bearing load.
Spiral
Under the Spiral Model, when bearing load the hands are first clenched, inverted, and abducted to position the outer wrists beneath the shoulder joints. The outer edges make contact with the ground, and each hand rolls inward across its transverse arch from pinky to index finger while the thumb simultaneously rotates under the wrist, forming a stable three-dimensional spiral structure.
Figure 17. Hand placed for bearing load.
Spiral
During tool use, the hand’s spiral framework rotates back and forth around its central axis. A fully developed hand can activate a mechanism called the Spiral Seesaw, alternating application of down-spin at either end of the rotational axis to manipulate torsion and spin for the most efficient tool use.
Figure 18. With the hand in level position (left), the thumb’s point of contact with the stick (A), the midpoint between the points of contact for the 3rd and 4th fingernails (B), and the stick’s rotational fulcrum (C) are all level with the horizon as well. When downspin is applied by the thumb at A (right bottom), the stick descends from D to E and strikes the drum pad while B rotates up above the horizontal plane due to the spiral construction of the hand.. When downspin is then applied by the fingers at B (right top), the stick again descends from D to E, rotating A up above the horizontal plane.
Spiral
During tool use, the hand’s spiral framework rotates back and forth around its central axis. A fully developed hand can activate a mechanism called the Spiral Seesaw, alternating application of down-spin at either end of the rotational axis to manipulate torsion and spin for the most efficient tool use.
Figure 18. With the hand in level position (left), the thumb’s point of contact with the stick (A), the midpoint between the points of contact for the 3rd and 4th fingernails (B), and the stick’s rotational fulcrum (C) are all level with the horizon as well. When downspin is applied by the thumb at A (right bottom), the stick descends from D to E and strikes the drum pad while B rotates up above the horizontal plane due to the spiral construction of the hand.. When downspin is then applied by the fingers at B (right top), the stick again descends from D to E, rotating A up above the horizontal plane.