SPLIT SOLE INDEPENDENTLY ADJUSTABLE LOAD-LIMITING FOOTWEAR

Abstract

A force absorbing device for a footwear appliance includes a shoe upper and a shoe sole having a planar sole surface, such that forces between the shoe upper and planar sole surface in ground contact are absorbed by storage and controlled release of kinetic energy in an elastic or resilient field. A footwear article such as a shoe or boot includes a split-sole system that redefines a shoe sole as coplanar surfaces having a force mitigating interface for receiving sudden forces and effectively mitigating these forces by storing kinetic energy and releasing it over time. An elastic field in the force mitigation interface is defined by a resilient material adapted to deform in response to the received force. Frictional engagement between the upper and lower sole may also be augmented by surface characteristics such as dimples, voids and lubricants, in addition to interference engagement with an elastic field.

Description

BACKGROUND

Athletic injuries, such as from overstressed musculoskeletal structures, can be traumatic and career ending. ACL (anterior cruciate ligament) injuries are particularly notorious and prone to recurrence. These and other injuries often result from some form of loads (e.g., forces and torques) transferred through the footwear of the athlete to the foot and on to an anatomical member, such as a bone, ligament, cartilage, tendon or other tissue structure. Mitigation of the transfer of these loads can substantially eliminate or alleviate injury risk to the foot, ankle, lower leg and knee. Because an athlete's footwear defines the ground interface, the footwear defines the focal point of potentially injurious load transfers. Shoe soles for athletic usage often employ high friction materials such as rubber and flexible polymers to “grip” the playing surface, and also employ a texture, ribs or protrusions on the bottom surface to avoid slipping. These conventional anti-slip materials and structures increase the load transfer from the athletes to the playing surface and when unmitigated, raise these loads an injury threshold.

Cushioning, padding and air bladders purport to distribute forces in conventional shoes, however these devices exhibit behavior similar to conventional springs. Most conventional mechanical springs have a single, consistent positive stiffness (force/displacement) throughout their deformation, e.g., stretching or compressing, until they reach the limit of their displacement, at which point the stiffness becomes fixed and substantially like a solid material. Conventional constant-force springs are characterized by large displacements, and low-forces, such as used in a clock spring or tape measure. Constant-force springs are generally characterized by minimal variance or “cushioning” once the constant force is reached and displacement continues equivalent to the constant force.

SUMMARY

A force absorbing device for a footwear appliance includes a shoe upper and a shoe sole having a planar sole surface, such that forces between the shoe upper and planar sole surface in ground contact are absorbed by storage and controlled release of kinetic energy in an elastic or resilient field. A footwear article such as a shoe or boot includes a split-sole system that redefines a shoe sole as coplanar surfaces having a force mitigating interface for receiving sudden forces and effectively mitigating these forces by storing kinetic energy and releasing it over time. An elastic field in the force mitigation interface is defined by a resilient material adapted to deform in response to the received force. Frictional engagement between the upper and lower sole may also be augmented by surface characteristics such as dimples, voids and lubricants, in addition to interference engagement with an elastic field.

Athletic injuries can be caused by sudden or impactful forces from running, twisting, turning, landing or falling, for example. Forces are generally transferred from a playing or ground surface to a skeletal or anatomical structure (bones, tendons, ligaments) that must travel through a footwear appliance or shoe. Often, injuries result from lateral or forward/backward forces on the bottom of the sole surface that transfer to the foot of the wearer with little absorption or mitigation from a conventional shoe. Configurations herein dispose a split plane structure in the shoe sole so that the lateral, forward, and backward forces against a ground or contact surface are absorbed rather then passed to the wearer/athlete. This results in a coplanar system where loads in the plane defined by the shoe sole are mitigated by a system that stores mechanical energy in mechanical, pneumatic, hydraulic, electrical, or magnetic elements of continuous, or discrete systems to control a load transfer between the split sole construction.

Additional usages address orthopedic needs of overstressed skeletal structures in an aging population. A societal need addressed is to reduce the likelihood of traumatic injuries to knees, ankles, and Achilles tendons, and to reduce repetitive loading injuries, as well as reducing foot discomfort and fatigue, foot irritation for diabetics, facilitating rehabilitation, and reducing the likelihood of ailments such as plantar fasciitis. It should be further noted that the force mitigation techniques herein are applicable to all dimensional components, e.g. lateral, left, right and vertical, regardless of the dimension which force mitigation is illustrated.

Configurations herein are based, in part, on the observation that footwear often includes minimal force absorption material or structure, and that which is present conforms to a conventional spring response. Unfortunately, conventional approaches suffer from the shortcoming that the conventional spring response, having a substantially linear force/displacement curve, rapidly approaches a maximum displacement such that high impact forces are often transmitted to the wearer with little mitigation. In other words, conventional active footwear employing layers of rubber or foam often employed in conventional shoe construction is insufficient to mitigate transfer of harmful loads. A maximum compression threshold is rapidly attained, and the shoe sole acts as a substantially solid material for transferring the load.

The disclosed system is adapted to moderate forces between the split-sole shoe construction, and may be modified or tuned for the rate of load increase with displacement, magnitude of compression, and release of stored energy. The stored energy will return the sole to its unloaded configuration when the load is released, e.g., during the next step and the shoe is off the ground. Accordingly, configurations herein substantially overcome the above shortcomings by disclosing a force absorption and mitigation system including an elastic field spring structure packaged for encapsulation in a shoe sole. The elastic field exhibits an engineered response, rather than a displacement-proportional response, so that abrupt or impact loads are met with a desired force independent of displacement for absorbing sharp or peak loads that tend to be associated with injury.

The disclosed elastic field provides a load-managing spring system that can be made to respond to different loads in different directions independently, and independently of rotation about a vertical axis, integrated into the middle a wide varies of shoe soles between the ground contact and foot support, with a wide variety of ground contact and traction elements and a wide variety of shoe uppers, without adversely influencing performance of a shoe compared to one without split-soles and load-limiting spring systems.

In further detail, configurations demonstrate footwear appliance for mitigating injurious forces. most notably from high intensity athletic or exercise endeavors, a force absorbing shoe sole, including a footbed configured for engagement with a foot of a wearer, and an outsole in communication with a ground or floor surface. A midsole is disposed between the footbed and the outsole, such that the midsole engages with the outsole through at least one force mitigation coupling for accommodating lateral displacement between the midsole and the outsole. The force mitigation coupling includes an actuator disposed in an elastic field, where the actuator is attached to the midsole and the elastic field embedded in the outsole. The outsole is further subdivided into a heel portion and separate toe or forefoot (fore) portion, such that the heel portion and the toe portion having separate respective engagements with the midsole for independent movement.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the invention will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

FIG. 1 is a plan view of the footwear appliance in a ground interface context;

FIG. 2 is a schematic of elastic bed spring response;

FIG. 3 is a diagram of a force mitigation engagement or module in the environment of FIG. 1;

FIG. 4 shows a shoe outsole and midsole configured for engagement using the force mitigation module of FIG. 3;

FIG. 5 shows a schematic diagram of an actuator and elastic field as in FIG. 3;

FIGS. 6A and 6B show actuator and elastic field configurations in the outsole/midsole interface of FIG. 4;

FIGS. 6C and 6D show a side elevation of the rotational flaps of FIG. 6B; and

FIG. 7 shows a banding or encapsulation for retaining the force mitigation modules between the midsole and outsole.

DETAILED DESCRIPTION

Configurations below demonstrate a force mitigation approach implemented in a horizontally “split” sole of a shoe or other footwear through a slidable, force controlled interface between the foot of an athlete/wearer and the playing surface or ground. Footwear experiences forces whenever the human foot changes direction against the horizontal ground or floor surface. Shoes, and in particular athletic shoes, are often designed to exhibit substantial friction with an underlying surface. Therefore, whenever force is generated between the shoe and the friction with the underlying surface, the foot receives the possibly injurious force. A force mitigation module between the foot and the outsole buffers or absorbs this force for preventing injury. A decoupling of the interface between the heel and toe allows moderated movement controlled by an elastic field defining a constant force spring response.

FIG. 1 is a plan view of the footwear appliance 100 (shoe) in a ground surface 110 interface context. In the course of use, the shoe incurs various exchanges of force with the ground surface. A lateral movement 102 incurs a lateral response 102′ from the surface 110 and friction of the outsole bottom against the surface. Configurations herein generally expect little to no force absorption by the surface, as typically the surface interface is frictionally and/or rigidly maintained by cleats or spikes so as to offer little force mitigation. A side heel movement 104 encounters a return force 104′, and a rotation 106, as might be encountered in a basketball jumpshot or rebound, incurs a return rotation 106′. Each of these return forces 102′, 104′ and 106′ are received by the foot anatomy unless mitigated by the sole as described herein.

FIG. 2 is a schematic of elastic field spring response. Unlike conventional springs, which exert an increasing resistance over a displaced distance, a constant force spring returns a constant counterforce over a displaced distance. Referring to FIG. 2, an actuator 120 disposed through an elastic field 130 incurs or receives a return force as the actuator 120 compresses the elastic field 130 in response to displaced travel, shown by arrow 122. Implementing the disclosed force mitigation module using a constant force, or substantially constant force spring structure, mitigates harmful transmission of harmful forces or impact though shoe soles. The assembly including the constant force spring implements an elastic field approach where a counterforce 124 is based on an area 132 of the engaged elastic field 130, rather than an entire length of an elongated or contracted spring. A beveled or angled leading edge 125 of the actuator 120 compresses a constant area, defined by a lateral length of the compressed region 127, which remains constant as the actuator 120 moves across the elastic field, while compressing the elastic field in a component of movement perpendicular to the displacement distance. The already compressed region 136 contributes little to the resistive counterforce 124, while the uncompressed portion 138 determines the extent of actuator travel encountering the constant counterforce 129. The disclosed elastic field spring for exerting a constant force response is also applicable in alternate contexts without departing from the claimed approach.

Transmission of loads from ground contact, via the sole, to the upper is controlled by relatively rigid actuators on one horizontal layer of the sole being displaced horizontally through another horizontal layer defined by an elastic field (EF). Controlled resistance to horizontal movements of these two layers, actuator and EF under loads caused by ground reactions (forces or moments) does work on the EF that absorbs energy that otherwise could be transmitted to the foot and leg and cause traumatic or repetitive injuries or discomfort, in one event or cumulative. The EF can be any sort of material that deforms elastically in response to pressure applied by a relatively rigid actuator. This elastic material could be a brush, foam, or rubbery material, such as a polyurethane, and may be 3d printed. The density and depth of EFs in the sole can be varied to control load transmission in different directions as actuators compress or interact with the EF in alternate configurations.

FIG. 3 is a diagram of a force mitigation engagement or module in the environment of FIG. 1. Referring to FIGS. 1-3, the footwear appliance 100 includes an upper 140, adapted to engage and surround a foot of a user/athlete, and a strobel or footbed 142 forming a contact surface with the wearer's foot. Depending on the shoe construction—performance athletic shoes minimize the bulk of the footbed—the footbed rests on a midsole 144. The midsole 144 engages with an outsole 146 in direct contact with the ground surface 110. The outsole 146 is therefore the lowermost, external facing surface in contact with the ground or playing surface 110 against which harmful forces emanate, typically from athletic maneuvers and high friction or holding power of the outsole 146 to the surface 110.

While conventional footwear designs employ intermediaries such as a fixed piece of foam rubber, air pockets, tubes and other cushioning, a conventional midsole is generally fixed to the outsole. In contrast, configurations herein deploy a force mitigation coupling through one or more force mitigation modules 150-1 . . . 150-2 (150 generally), that each exhibit force mitigation through a constant force spring response. Separate force mitigation modules 150 engage a heel portion 148-1 and a toe portion 148-2 of the outsole 146, respectively.

FIG. 4 shows a shoe outsole 146 and midsole 144 configured for engagement using the force mitigation modules 150 of FIG. 3. Referring to FIGS. 1-4, in the footwear appliance 100 for mitigating injurious forces, the force absorbing shoe sole configuration encapsulates the shoe upper 140 and footbed 142 for engagement with a foot of a wearer, and the outsole 146 in communication with a ground or floor surface 110. The midsole 144 is disposed between the footbed 142 and the outsole 146, and is engaged with the outsole 146 through at least one force mitigation coupling, defined by the force mitigation modules 150, for accommodating lateral displacement between the midsole 144 and the outsole 146. To ensure encapsulation and integrity between the midsole 144 and outsole 146, elongated prongs 160 are adapted to engage horizontal slots on perimeter loops 162 to ensure the midsole 144 and outsole 146 remain in a parallel plane “split sole” configuration.

Any suitable arrangement of force mitigation couplings may be used to engage or attach the outsole 146 for force mitigated movement with the midsole 144. In an example configuration, the outsole 146 the heel portion 148-1 and the toe portion 148-2, such that the heel portion 148-1 and the toe portion 148-2 have separate respective engagements with the midsole 144 for independent movement. At least one force mitigation coupling 150 engages between the heel portion and an aft section of the midsole, and at least one force mitigation coupling engages between the toe portion and a fore section of the midsole, such that each of the force mitigation couplings is defined by an actuator 120 adapted for slidable movement across an elastic field 130. Separate toe (fore) and heel (aft) outsole portions 148 decouple control between the fore and aft foot movements. As discussed further below, the outsole portions 148 as well as the elastic field 130 and actuator 120 forms provide for independent regulation and mitigation of forces directed fore and aft, left and right, and rotating about an axis, particularly when the rotational axis is distal from the shoe.

The exploded view of FIG. 4 depicts the force mitigation modules 150 disposed in a recession 149. Each force mitigation module 150 defines a force mitigation coupling including an actuator 120 disposed in an elastic field 130, such that the actuator 120 attaches directly or indirectly to the midsole 144 and, and the elastic field 130 is embedded in the outsole 146. In the example configuration, this takes the form of a recession 149-1 in the heel portion 148-1 and a recession 149-2 in the toe portion 148-2 (148 generally). Each of the recessions is configured to contain a force mitigation module 150 defining the force mitigation coupling. An attachment of the actuator 120 of each of the force mitigation modules 150 to the midsole 144 therefore provides for mitigating forces between the midsole 144 and the outsole 146.

The physical communication of the split-sole arrangement generally allows for a slidable engagement between the midsole 144 and outsole 146 in regions between the recessions 149 and force mitigation modules 150. Modest friction and/or friction mitigating lubricants or textures may be provided, however in general, the midsole 144 and outsole 146 define opposed, parallel planes in a slidable engagement moderated by the force mitigation modules 150 as forces are generated between the user and the ground surface 110.

In implementation in a footwear appliance, there are four components for deploying a system for effective force control and modulation within the space afforded in a shoe sole.

1. Elements of an AEF system are oriented and sized to provide independence in adjustment of responses, referring to forces where displacement is imposed in different directions. The system can be tuned to a level of stiffness or modest response (soft), and then, after reaching a desired response load or injury threshold, displace, at that load, to absorb energy that might otherwise case discomfort or injury. An example of actuator and elastic field engagement is shown in FIG. 5.

2. Separate forefoot and heel sections that can rotate and displace independently from each other, shown in FIG. 4 above. This might be most effective for limiting traumatic injuries for shoes with cleats, as are used in soccer and lacrosse. It could also be good for reducing loads that cause repetitive type injuries. In limited circumstances, shoes without separate fore and aft sections might be preferable. Load-limiting spring systems as described above can be placed in the heel and toe sections. For shoes without separate forefoot and heel sections one load-limiting spring system could be used.

3. An interlocking system that allows for several millimeters of horizontal motion and large rotations between the split soles, while limiting vertical motion, shown in FIGS. 6A and 6B, below.

4. A sidewall that can maintain the cleanliness of the split-sole interface without carrying significant loads that would mask the desired load transfer control between the soles provided by the tunable AEF spring system, shown in FIG. 7. The sidewall would attach to the bottom of the split-soles and to the top and extend over the split. It would be advantageous to make the height of the side wall longer in order to complement control loads from elastic elements.

FIG. 5 shows a schematic diagram of an actuator 120 and elastic field 130 as in FIG. 3. In general, the actuator 120 is a rigid material and the elastic field 130 is a resilient, compressible material, such that the elastic field exerts a force with a component in a direction perpendicular to a direction of compression exerted by the actuator. The actuator 120 has a compressive surface oriented at an angle to a direction of translation or displacement across the elastic field 130, the angle exerting a compressive force on the elastic field in a direction perpendicular to the direction of translation. FIG. 2 shows a 45° orientation of the engaging surfaces, translating to a 90° redirection of actuator 120 translation to the compression direction 129 of the elastic field 130, however other angles of orientation may be employed depending on the material properties and a tendency for friction to “drag” the elastic field as the actuator 120 slidably engages.

An example configuration limits load transmissions through shoe soles with an actuator in an elastic field (AEF) tunable nonlinear spring system that can be incorporated at the interface between split soles in a shoe of any suitable upper and encounter any kind of ground interface. Note that the actuator 120 is relatively hard (high elastic modulus material), such as molded soccer cleats. The elastic field 130 has an effective elastic modulus lower than the actuator 120. A difference in the elastic moduli of the two elements should be sufficient so that the interface between the actuator 120 and the elastic field 130 is substantially maintained during displacement across the split sole parallel to the split and a contact is maintained that provides an elastic response force across the interface parallel to the split, or a torque about a vertical axis perpendicular to the split.

The elastic material defining the elastic field 130 is preferably a solid rubbery material, a foam, a brush, or other resilient material that can deform recoverably in one direction while exerting a force with a component perpendicular to the compression direction across its interface with the actuator. This interface should have a coefficient of friction sufficiently low so that the friction forces in the perpendicular direction are less than the elastic recovery forces in that direction exerted by the elastic field.

As the actuator 120 becomes displaced across the elastic field 130, physical

Independent parameters of each are defined by:

• • step height t; and width
  • elastic field thickness t_e
  • actuator thickness t_a
  • interface angle α

Resulting geometric dependencies include:

$\begin{array}{c}\alpha ={\theta }_e={\theta }_a\\ t_i=r_a\left(1-\cos \alpha \right)+r_e\left(1-\cos \alpha \right)\end{array}$

• • for actuator step radius r_a
    • step lengths d_a=r_a sin α
  • elastic field step radius r_e
    • step length d_e=r_e sin α

The angles and thicknesses deployed in the actuator 120 and the elastic field 130 can therefore “tune” how aggressively incoming forces are distributed and mitigated within the limits of the material thickness and the allowable distance for displacement in a shoe sole.

FIGS. 6A and 6B show actuator and elastic field configurations in the outsole/midsole interface of FIG. 4. By deploying a cross shaped actuator 120, four primary directions of force are addressed: fore (toe), aft (heel), left and right. Referring to FIGS. 6A, the actuator 620 includes a plurality of arms 621-1 . . . 621-4 (621 generally) extending from the actuator 620, such that each of the arms 621 extends in an arm direction, and has an area based on a responsive force to translation in the arm direction from the elastic field 130. A circumferential elastic field 630 surrounds the actuator 620 in a square rounded square pattern. As the elastic field 630 tangentially contacts the arms 621, the force mitigation couplings between the midsole 144 and outsole 146 decouple a force responsive to movement of the actuator in the fore, aft, left, right and rotational directions, as each has a corresponding arm 621 in contact.

It should further be noted that the plan view of FIGS. 6A and 6B abstracts the angle and slope shown in FIGS. 2 and 5, and it is understood that the actuator 120, 620 engage the elastic field 630 at a predefined angle for elastic field compression, as a “butt” engagement (0°) would result in a conventional foam cushion that responds as a linearly increasing spring force, not as a constant force spring of an elastic field 130. Angled edge 630′ denotes an outermost edge, defined by the upper (midsole side) of the elastic field, using the angular orientation of FIGS. 3 and 5. Similarly, the lowermost edge of the actuator (outsole side) is approximated by angled limit 620′.

In operation, it is entirely likely that incoming forces will be a combination of the four arm directions 621, and may contain a rotational component as well. The clastic field 630 further comprises rotational guides 625, such that the rotational guides 625 are defined by portions of the elastic field offset from an arm 621 direction of the plurality of arms. The rotational guides 625 are disposed for actuator contact resulting from a rotation or a component of movement aligned with two or more of the arm directions from the arms 621.

The rotational guides 625 are therefore engaged by rotation of the actuator 620, or by a combination of movement components “between” the arms 621, tending to dispose the actuator 620 off center. Arms on the actuator can be adjusted in width to adjust reactions in different directions. Ends on arms 621 can be radiused about the center so that rotation can be controlled. These rotational guides 625 impose ant-rotational response, and can be tuned (sized) to regulate rotational forces separately from the forces aligned with any of the specific arms 621-1 . . . 621-4. Similarly, each of the arms can be sized to favor additional resistance, say left and right over fore and aft by sizing the left and right (621-2, 621-4) arms larger than the fore and aft (621-1 and 621-3) for imposing a larger elastic field in the left and right directions.

Referring to FIGS. 6B, another configuration employs a modular elastic field 730, including elastic field regions 730-1 . . . 730-4 (730 generally) aligned with the arms 621. Rotational and component resistance is moderated by rotational flaps 725. Referring also to FIGS. 6C and 6D, a side elevation of the rotational flaps of FIG. 6B is shown. The rotational flaps 725 are defined by portions of the elastic field extending upright and adapted for folding into a recess 726 towards horizontal in response to actuator 620 movement.

FIG. 7 shows a banding or encapsulation for retaining the force mitigation modules between the midsole and outsole. Referring again to FIG. 4, a vertical engagement between the midsole 144 and outsole 146 ensures vertical integrity in a z-axis while allowing lateral force mitigation in the x-y plane, therefore ensuring the outsole 146 does not separate from the midsole 144. FIG. 7 shows an overlapping engagement 165 for vertical restraint between the midsole 144 and outsole 146, through overlapping slidable segments 166-1 . . . 166-2 (166 generally). The slidable segments 166 are generally aligned on a circumferential perimeter while the force mitigation modules 150 reside well inboard so as not to conflict. As noted above, FIG. 4 shows elongated prongs 160 adapted to engage horizontal slots on perimeter loops 162. Other suitable approaches, such as an elastic banding, perimeter adhesion or pivoting fixtures such as dowels, screws or rivets may also be employed.

While the system and methods defined herein have been particularly shown and described with references to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims

1. In a footwear appliance for mitigating injurious forces, a force absorbing shoe sole, comprising: a footbed configured for engagement with a foot of a wearer;an outsole in communication with a ground or floor surface; anda midsole, the midsole disposed between the footbed and the outsole, the midsole engaged with the outsole through at least one force mitigation coupling for accommodating lateral displacement between the midsole and the outsole,the outsole having a heel portion and a toe portion, the heel portion and the toe portion having separate respective engagements with the midsole for independent movement.

2. The method of claim 1 wherein the force mitigation coupling includes an actuator disposed in an elastic field, the actuator attached to the midsole and the elastic field embedded in the outsole.

3. The method of claim 1 further comprising a plurality of the force mitigation couplings, including: at least one force mitigation coupling between the heel portion and the midsole;at least one force mitigation coupling between the toe portion and the midsole,each of the force mitigation couplings defined by an actuator adapted for slidable movement compressing an elastic field.

4. The method of claim 3 wherein the actuator is a rigid material and the elastic field is a resilient, compressible material, the elastic field exerting a force with a component in a direction perpendicular to a direction of compression exerted by the actuator.

5. The method of claim 3 wherein the actuator has a compressive surface oriented at an angle to a direction of translation across the elastic field, the angle exerting a compressive force on the elastic field in a direction perpendicular to the direction of translation.

6. The method of claim 3 wherein the force mitigation couplings provide independence of responsive movement of the actuator in the fore, aft, left, right and rotational directions.

7. The method of claim 3 further comprising: a plurality of arms extending from the actuator, each of the arms extending in an arm direction and having an area based on a responsive force to translation in the arm direction from the elastic field.

8. The method of claim 3 further comprising a circumferential elastic field.

9. The method of claim 3 further comprising a modular elastic field.

10. The method of claim 7 further comprising rotational guides, the rotational guides defined by portions of the elastic field offset from an arm direction of the plurality of arms, the rotational guides disposed for actuator contact resulting from a rotation or a component of movement aligned with two or more of the arm directions from the arms.

11. The method of claim 7 further comprising rotational flaps, the rotational flaps defined by portions of the elastic field extending upright and adapted for fold towards horizontal in response to actuator movement.

12. The method of claim 1 further comprising: a recession in the toe portion;a recession in the heel portion;each of the recessions configured to contain a force mitigation module defining the force mitigation coupling; andan attachment of the actuator of each of the force mitigation modules to the midsole for mitigating forces between the midsole and the outsole.