Shoe Having Spring System

The present patent application claims priority benefit to U.S. provisional patent application No. 63/656,995, filed on Jun. 6, 2024, the entire content of which is incorporated herein by reference.

This disclosure relates generally to a shoe, and more particularly to a shoe having a spring system.

In general, running or walking requires a specific innate sequence of subtle movements of ankle, calf, and foot adjustments in order to shift weight from heel to toe which then allows the next step forward. These movements are subtle and instinctual. For example, the heel of the foot when walking or running, impacts the ground first while the heel primarily absorbs shock and intense energy that might reverberate throughout the body. The weight of the person must then instantaneously shift from the heel, by instinctive movement of the knee and ankle, toward the ball region of the foot. Next, the forefoot and toe region of the foot provide the last contact with the ground, as the foot uses stored energy from tendons and fascia to push off the ground. Generally, shoes have been designed to protect feet and absorb shock, but by buffering shock, the natural mechanics that coordinate the knee, ankle, and foot are slowed down and interfere with natural timing and the flow of required sequential movements. These movements are better served to be instinctive, occurring in milli seconds, not depending on any conscience adjustments. Consequently, shoes that impede natural mechanics of the knee, ankle, and foot movement (that evolved over thousands of years) will not benefit the wearer. Only shoes that accept, support, and enhance the natural cycle for forward movement will benefit the wearer.

An aspect of the present invention is to provide sequential springs for a shoe with a negative heel and a midsole fulcrum used to accelerate the shift of weight. The initial shoe spring includes a V-shaped back portion having a lower platform portion configured to contact the sole of the shoe and an elevated platform portion (also referred to herein as a raised springboard portion) that is configured to support the heel of the wearer's foot, the elevated springboard portion intersecting the lower platform portion at an intersection point to form an angle relative to the lower platform portion such that the elevated springboard portion is spaced apart from the lower platform portion by a distance at a location opposite the intersection point. The elevated springboard portion remains elevated until the wearer straightens his body and allows his weight to compress the springboard platform that is configured to move closer to and away from the lower platform portion so as to provide a springboard effect that raises the heel in an arc to shift forward on the fulcrum that assists the wearer in shifting his/her weight as the body naturally moves forward.

Another aspect of the present invention is to provide a shoe including a lower portion including a sole configured to support a foot of a wearer; an upper portion configured to cover the foot of the wearer; and a shoe spring having a V-shaped back portion provided near a heel region of the shoe, the V-shaped back portion having a lower platform portion and a raised springboard portion that is configured to support a heel of the foot of the wearer. The raised springboard portion intersects the lower platform portion at an intersection point to form an angle relative to the lower platform portion such that the raised springboard portion is spaced apart from the lower platform portion by a distance at a location opposite the intersection point. The raised springboard portion is configured to move closer to and away from the lower platform portion so as to provide a cantilever spring effect in an arc without having contact with a back of the shoe. A further aspect of the present invention is to provide a shoe spring kit for a shoe including a V-shaped spring portion having a lower platform portion and a raised springboard portion, the raised springboard portion intersecting the lower platform portion at an intersection point to form an angle relative to the lower platform portion such that the raised springboard portion is spaced apart from the lower platform portion by a distance at a location opposite the intersection point. The raised springboard portion is configured, at a static position, to bend and move closer to and away from the lower platform portion so as to provide a cantilever spring effect.

Another aspect of the present invention is to provide a shoe spring kit for a shoe including a fulcrum configured to be coupled to a sole of the shoe; a V-shaped spring configured to be coupled to the fulcrum; and a front spring having a front end and a back end, the back end of the front spring configured to be coupled to the fulcrum. When mounted to the shoe, the front end of the front spring is spaced apart from the sole, and the V-shaped spring is coupled to an exterior surface of the sole.

Shoe technology and design should focus on creating an environment where intense energy created by movement is immediately available to enhance the next movement, an environment without shock to the body, and finally enhancing the natural flow of movement through an environment that enables quicker movements naturally. These goals are achieved by the gestalt of the present disclosure and fabrication of uniquely shaped materials that work in sequential order that enable the evolution of the shoe.

Additional features, advantages, and embodiments of the invention are set forth or apparent from consideration of the following detailed description, drawings and claims. Moreover, it is to be understood that both the foregoing summary of the invention and the following detailed description are exemplary and intended to provide further explanation without limiting the scope of the invention as claimed.

Shoe systems are provided that improve the mechanics, efficiency, and/or performance of shoes in use. In use, the initial impact in the heel area of the foot is of special interest with runners because, in general, the heel area initially absorbs the highest amount of impact energy with the ground while providing a stable landing, but depending on the millisecond that occurs before the shift of weight, the runner will gain momentum or will slow down. Currently, shoes are provided with a rubber sole or air bladders enhanced at the heel area with additional rubber or foam thickness to provide additional cushioning of the foot during the initial impact of the heel area with the ground. The unintended consequence is that the shift of weight is more than likely delayed, interfering with forward momentum. Thus, improvement is still needed to enhance the mechanics, efficiency, and energy return, allowing superior performance of shoes in use and reduce injury and wear and tear.

A detailed running technique is described in “Running Technique Principle 5: Utilise Your Natural Springs,” by Brad Beer, dated Feb. 15, 2016, Running, https://www.pogophysio.com.au/blog/running-technique-principle-5-utilise-your-natural-springs/, the entire content of which is incorporated herein by reference. The fifth principle to running with great technique is to utilize what is referred to as a runner's ‘natural springs’. The same anatomical foot and leg structures that assist in lessening the loads on the legs on impact, such as the muscles, tendons, and fascia, also assist with propulsion.

Therefore, when a runner over-strides and subsequently heel strikes, not only are they by-passing their own shock absorbers they are also in effect bypassing their body's very own natural springs. The natural springs are the tendon-related structures in the foot and lower leg, including the Achilles tendon, calf muscle complex, and plantar fascia of the foot. When a runner lands on their mid-or forefoot, these natural spring structures generate energy and propulsion as they are stretched and then ‘released’.

The principle in biomechanics is known as ‘elastic recoil’. Elastic recoil applies to the tendons of the human body. The energy that is created by recoiling is generated by the plantar fascia of a runner's feet, the Achilles tendon, and the tendons in the calf complex. This occurs when a runner impacts the tendons stretch as they absorb load, before they recoil and provide the runner with propulsion.

Structurally, tendons can undergo stretching or deformation of somewhere between 4 and 6 per cent of their original length. When at rest, the tendon fibers, called collagen, run parallel in wavy lines (think of rolling hills in the countryside). Under load (such as at the time of foot impact), the collagen fibers are aligned as they straighten and store energy. As the lower limb muscles contract the tendons then release their stored-up energy. Amazingly, the recoil generated by a runner's leg tendons under the weight bearing or ‘stance’ phase of the gait cycle provides up to 50 per cent of the propulsive forces required for each stride.

This elastic energy is released as kinetic (movement producing) energy during the ‘toe off’ part of the running cycle. Elastic recoil requires very little energy, and is available for runners, unless these springs are bypassed by over-striding or running with less than an ideal technique.

When a runner over-strides, they inadvertently rob themselves of this free propulsive energy. Efficient runners store energy from one stride to the next and release it for push off. If it appears as though these runners have springs in their shoes, it is because they actually do in the form of tendon-springs.

The role that the tendons play in efficient and sustained distance running is evidenced by the body frames of elite distance runners. Typically, an elite distance runner's frame is composed of very little muscle mass, leaving just bones and tendons as the main propulsive structures. The fact that such a large proportion of their body mass is tendon tissue highlights the importance of tendons in fast and economical running.

In order to run pain and injury free, and also faster, it is also helpful to have “stiff tendons.” Stiffer tendons are able to store more energy because greater energy is required to stretch them. This greater energy is stored in the tendons and released at toe off as the muscles of the calf and lower leg contract. To improve the elastic recoil of your lower limb tendons “you need to make your tendons stiffer.” This can be achieved by strengthening the fibers that make up the tendons with exercises such as single leg calf raises and by supplementing the tendon recoil by using a stiff spring having a composite material (e.g., carbon graphite reinforced material) that move like tendons in the same motion and timing as required by the runner.

is a perspective view of a shoe having a V-shaped spring comprising a stiff composite material (e.g., a stiff carbon graphite reinforced material) that bends to absorb and release energy as the wearer shifts weight, according to an embodiment of the present disclosure. The shoe is shown as being transparent to show various features of the shoe provided inside the shoe. The shoecomprises a lower portionincluding a solefor supporting a foot of a wearer and an upper portionfor covering the foot of the wearer. The soleincludes a front sole portionA for supporting the ball and toes of the foot of the wearer and a back sole portionB for supporting the heel of the foot of the wearer. In an embodiment, the shoeincludes a shoe spring. The shoe springincludes a front platformA separately comprising a composite material (e.g., a carbon graphite reinforced material) that deforms and straightens under pressure and releases energy at lift off when the front platformA snaps back to its original shape and V-shaped back portionB. The front platformA is provided at the front of the shoe. The back portionB (e.g., V-shaped) is provided near the heel region of the shoe. The front platformA together with V-shaped back portionB form a Y-shape, as shown in.

The V-shaped spring portionB has a lower platform portionand a raised springboard portionthat intersect at intersection pointto form an angle θ with the lower platform portion. The front platformA is configured to contact the front sole portionA. The lower platform portionis configured to contact the back sole portionB. The raised springboard portionis configured to support the heel of the wearer of the shoe. The raised springboard portionis spring-loaded relative to the lower platform portion. The raised springboard portionforms the angle θ relative to the lower platform portion. The raised springboard portionis spaced apart from the lower platform portionby distance d at a location opposite the intersection point. The distance d can be from 0.25 inch to 4.0 inches (for example, from 0.25 inch to 2.5 inches) depending on a height of the flat (not raised) heel area of the shoeand the height of the shell of the shoe or sandal. The intersection pointcan be positioned over a fulcrumof the shoe. The raised springboard portionis configured to move closer to and away from the lower platform portionas it bends so as to provide a cantilever spring effect on an arc to assist in the transfer of the weight of the wearer to the fulcrum that tips the weight to the front spring. When the back spring begins its cycle, it bends as the shoe tips back on the fulcrum, the calf muscles and foot tendons and fascia are extended and lengthened (as in calf stretch). As the shoe tips forward, the calf muscles and foot tendons release energy and propel the wearer forward. The shoe springcan be attached to the sole. For example, the shoe springcan be provided as an insert. In an embodiment, the raised springboard portionof the back portionB (e.g., V-shaped) can be made from a resilient composite material such as a carbon graphite reinforced material. In an embodiment, the front platformA together with back portionB (e.g., V-shaped) forming the Y-shape can be made from a resilient composite material such as a carbon graphite reinforced material.

The fulcrumcan be made from a flexible material such as rubber or other compressible plastic. In an embodiment, the fulcrumis provided at the mid-point of the sole. The fulcrumis configured as an essential pivot to propel forward momentum created by the back springboard rising in an arc causing an immediate shift of the weight from the bounce of the shoe heel striking the ground to force the shift of weight toward the ball of the foot causing amplified pressure on the front spring that accelerates the movement and height of the foot leaving the ground. This is consistent with the cycle of running mechanics. The quicker the foot leaves the ground, milliseconds are saved and acceleration is enhanced. The fulcrumcan have a cylindrical shape. The fulcrumcan have a cylindrical diameter between about 0.5 inch and 1 inch, for example 0.75 inch. The fulcrumcan be fastened to the soleusing fastenersA (e.g., fastened to an exterior surface of the sole) or by adhesive to a flexible composite material (e.g., a carbon graphite reinforced material) plate that is glued to the bottom of the shoe. The fastenersA can be one or more screws or clips, etc. In an embodiment, the shoecan include the fulcrumduring the manufacturing of the shoe. In another embodiment, the shoecan be adapted to receive the fulcrumafter manufacturing of the shoe. Hence, the fulcrumcan be sold separately from the shoeand any shoe can be adapted to receive the fulcrum. The interior of the back end of the shoe has extra space that allows the springboard to compress and raise in an upward arc without friction from the interior of the shoe.

In an embodiment, the shoe springcan be incorporated into the shoeduring manufacturing of the shoe. In another embodiment, the shoe springis configured to be slipped into the shoeover the sole, or be attached to a flexible graphite plate attached to the sole by adhesive, after manufacturing of the shoe. Therefore, any shoe can be modified by adding the shoe springwith the back portionB (e.g., V-shaped).

In an embodiment, the shoe springincludes stiff composite material (e.g., stiff carbon graphite reinforced material) that can bend under the weight of the wearer. In an embodiment, a spring membercan be provided between the lower platform portionand the raised springboard portionof the shoe spring. In an embodiment, the lower platform portioncan be attached to the raised springboard portionvia a static hingeprovided at the intersection point. The spring memberis configured to counter react to a force applied to the raised springboard portion.

In use, when walking or running, the back sole portionB for supporting the heel of the foot of the wearer impacts the ground first. Under the weight of the wearer, the heel of the foot of wearer will push on the raised springboard portionof the shoe springas a springboard. As a result, the raised springboard portionbends closer to the lower platform portionand the distance d decreases. As the spring snaps up, the raised springboard portionraises the heel in a forward arc, the fulcrum tips the shoe forward. The weight of the person then naturally shifts forward onto the ball of the foot that compresses the forward spring. The forefoot and toe region of the foot provide the last contact with the ground as the front spring rolls forward, deforms and releases its kinetic energy causing the foot to lift from the ground, while the fulcrum continues to tip forward. The front sole portionA touches the ground. The back sole portionB also lifts from the ground which allows the back spring to return to its potential open state until the foot in dorsiflexion contacts the ground and the spring contracts while it stores energy to be released as weigh is shifting.

The initial impact in the heel area of the foot is of special interest with runners because, in general, the heel area absorbs initially the highest amount of impact energy with the ground while providing a stable landing, which as suggested previously, might slow down the runner. Currently, many shoes are provided with a rubber sole enhanced at the heel area with additional rubber or foam thickness to provide additional cushioning of the foot during the initial impact of the heel area with the ground. However, the use of additional rubber or foam thickness does not provide useful cushion and/or substantial return of energy and propulsion. On the other hand, when the spring memberis used, the spring membercomprising stiff composite material (e.g., stiff carbon graphite reinforced material) which initially becomes compressed under the weight of the wearer and absorbs most if not all of the shock. In that instant, the spring decompresses (like a tendon) as the wearer shifts his/her weight forward to propel the heel of the wearer forward. As a result, not only the shoe springsoftens the landing of the foot of the wearer on the ground, the shoe springalso helps to propel the foot of the wearer forward, thus adding to the wearer forward momentum.

shows a shoe spring, according to another embodiment of the present disclosure. As shown in, the shoe springincludes a front platform portionA and V-shaped back portionB. The front platform portionA can be provided at the front of the shoe. The V-shaped back portionB is provided near the heel region of the shoe.

The V-shaped spring portionB has a lower platform portionand a raised springboard portionthat intersect at intersection lineto form an angle θ with the lower platform portion. The front platformA is configured to contact the front sole portionA (shown in). The lower platform portionis configured to contact the back sole portionB (shown in). The raised springboard portionis configured to support the heel of the wearer of the shoe. The raised springboard portionis spring-loaded relative to the lower platform portion. The raised springboard portionis spaced apart from the lower platform portionby distance d at a location opposite the intersection line. The distance d can be between about 0.25 inch to 4.0 inches (for example, from 0.25 inch to 2.5 inches) depending on a heigh of the heel area of the shoe. The intersection linecan be positioned over the fulcrumof the shoe(shown in). The shoe springcan be attached to the bottom of the sole(shown in). The lower platform portionand the raised springboard portionthat intersect at intersection lineto form an angle θ with the lower platform portionare joined together using an adhesive materialA, such as for example epoxy. The raised springboard portionand the lower platform portioncan be reinforced and supported and joined together by a triangular wedgeB.

In an embodiment, the shoe springcan be made from a flexible composite material (e.g., a flexible carbon graphite reinforced material). In an embodiment, the raised springboard portioncan be made from a resilient composite material such as a carbon graphite reinforced material. In an embodiment, a resilient membercan be provided between the lower platform portionand the raised springboard portionof the shoe spring. In an embodiment the resilient membercan be made of flexible composite material such as a carbon graphite reinforced material. When the heel of the foot of a wearer pushes on the raised springboard portion, the resilient memberflexes or bends and when the wearer shifts weight, the heel of the foot of the wearer rises forward, in an arc as the runner shifts weight and the resilient memberexpands and returns to its natural state. As a result, not only shoe springsignificantly softens the landing of the foot of the wearer on the ground, the shoe springthrough the resilient memberalso helps to coordinate the natural movement of the knee, ankle and foot to complete the cycle to propel the wearer forward thus adding to the wearer forward momentum.

is a perspective view of a shoe having a torsion spring, according to an embodiment of the present disclosure. As shown in, the shoeis similar in many features with the shoe shown in in. The shoeincludes a torsion spring. The torsion springis provided within a fulcrum. The fulcrumis located at the mid-point of the sole. The fulcrumis configured facilitate shifting of the weight of the wearer from the back to the front to accelerate the movement of the foot in leaving the ground. The fulcrumcan be made from rubber or other compressible plastic. For example, the fulcrumcan have a cylindrical shape. The fulcrumcan have a cylindrical diameter between about 0.5 inch and 1 inch, for example 0.75 inch. The fulcrumis attached to a surface of the solethat is configured to contact the ground.

The shoefurther includes at least one armA connected to the torsion spring. The at least one armA extends through holes (shown in) provided within the soleinto the interior of the shoe.

is a see-through view of an interior of the shoedepicting the at least one armA connected to the torsion springextending into the interior of the shoe, according to an embodiment of the present disclosure. For example, two armsA are shown extending into the interior of the shoethrough openings or holesprovided with the sole. Therefore, while the torsion springis provided within the fulcrumon the soleoutside of the shoe, the at least one armA is connected to the torsion springand extends to the interior of the shoe.

In an embodiment, at least one armA can be curved at the back of the heel area of the shoeto conform to the general shape of the heel of the foot of the wearer. In an embodiment, the at least one armA can be curved or looped at the backB, as depicted in. In another embodiment, two armsA can be provided and the two armsA can be connected to each other at the backB. In an embodiment, the backB can be bent upward, as shown in. In an embodiment, a plurality of tiesC (shown in) can be provided to connect the two armsA to provide support to the heel of the foot of the wearer. In another embodiment, instead of or in addition to the plurality of tiesC, a fabric or flexible material (e.g., plastic, leather, etc.) may also be provided.

As shown inand, the shoemay also include a stopto block the at least one armA from raising above a certain distance h from the sole. In an embodiment, the backB can be configured to abut the stopso as to limit an upward extension of the at least one armA. The distance h can be between about 1 inch to about 3 inches.

As shown in, the shoemay also include a harness. The harnessmay include a bandand a buckle. The harnessincluding the bandand buckleare configured to hold the foot of the wearer inside the shoewhen the heel of the foot of the wear is propelled by the at least one armA pushed by the torsion spring. In an embodiment, the bandcan be an elastic band.

As shown in, the shoealso includes a front springdisposed at the front portion of the sole. The front springcan be made of resilient composite material such as a carbon graphite reinforced material. In an embodiment, the front springcan have a U-shape (or an exaggerated Bobby pin shape) with an open portionA of the U-shape is oriented forward relative to the shoe. In an embodiment, the front springhas a shape that is similar to a “clothes pin” shape. The front springhas a bottom portionB. The bottom portionB is configured to stretch or bend under an applied force (e.g., a force applied by the weight of person wearing the shoewhen the weight shifts forward onto the ball of the foot). The front springhas a top portionC. The top portionC contacts the soleof the shoe. The top portionC has a shape that substantially follows the shape of the soleat the front portion of the solebut can extend about.inch on each side of the sole to enhance stability. In an embodiment, the top portionC of the front springcan be longer than the bottom portionB of the front spring. For example, the top portionC can be longer than the bottom portionB by about 1 inch to 1.5 inches that allows the bottom portion to compress and slide forward on the top portion. The front springis described further while referring to.

is a perspective view of an exterior of the shoeat the sole showing the front spring, according to an embodiment of the present disclosure. As shown in, the bottom portionB of the front springis wider than the sole. In an embodiment, the bottom portionB extends about 0.5 inch on both sides of the soleof the shoe, as shown in. The shoeincludes a plurality of channels. The plurality of channelsare mounted to the soleand are configured to receive the front spring. The front springcan slide into the plurality of channels. By providing the plurality of channels, the front springcan be easily replaced if worn or damaged. For example, the plurality of channelscan be two channels provided on each side of the sole. The front springcan also be removed from an adhesive and replace the front springwith a new front spring, if worn or damaged. The front bottom of the shoeis topped by the front springthat is mounted on a flexible graphite plate that extends past the fulcrum. The fulcrumcan be mounted to the plate same flexible plate, as shown in. The front springmay be covered by a thin rubber sole to provide traction.

is a perspective view of a shoe having a V-shaped spring, according to another embodiment of the present disclosure. The shoeis shown as being transparent to show various features of the shoe provided inside the shoe. The shoecomprises a lower portionincluding a solefor supporting a foot of a wearer and an upper portionfor covering the foot of the wearer. The soleincludes a front sole portionA for supporting the ball and toes of the foot of the wearer and a back sole portionB for supporting the heel of the foot of the wearer. In an embodiment, the shoeincludes a shoe spring. The shoe springincludes a V-shaped spring portionB provided near the heel region of the shoe. The present embodiment is different from the embodiment shown inin that the shoe springdoes not have a front platform (such as the front platformA in the shoe).

The V-shaped spring portionB has a lower platform portionand a raised springboard portionthat intersect at intersection pointto form an angle θ with the lower platform portion. In an embodiment, as shown in, the V-shaped spring portionB is provided inside the shoetoward the heel portion or the back sole portionB. In an embodiment, the lower platform portionof the V-shaped spring portionB is configured to contact the back sole portionB at the interior of the sole. The raised springboard portionis configured to support the heel of the wearer of the shoe. The raised springboard portionis spring-loaded relative to the lower platform portion. The raised springboard portionforms the angle θ relative to the lower platform portion. The raised springboard portionis spaced apart from the lower platform portionby distance d at a location opposite the intersection point. The distance d can be from 0.25 inch to 4.0 inches (for example, from 0.5 inch to 2.5 inches), depending on a height of the heel area of the shoe. In an embodiment, the intersection pointcan be positioned over the fulcrumof the shoeor near a mid-point the sole. The raised springboard portionis configured to move closer to and away from the lower platform portionso as to provide a cantilever spring effect without contacting the back of the shoe. The shoe springcan be attached to the sole. The raised springboard portionmay include a curved portionC provided at a back area of the shoeat a location opposite the intersection point.

In an embodiment, the shoe springcan be incorporated into the shoeduring manufacturing of the shoe. In another embodiment, the shoe springis configured to be slipped into the shoeover the soleafter manufacturing of the shoe. Therefore, any shoe can be modified by adding the shoe springwith the V-shaped spring portionB. In an embodiment, the shoe springcan be made from a resilient composite material including, for example, a flexible carbon graphite reinforced material and/or a flexible glass fiber reinforced material. The resilient composite material of the shoe springcan be selected according to desired spring properties of the V-shaped spring portionB. In an embodiment, the raised springboard portioncan be made from a resilient composite material such as a carbon graphite reinforced material. The V-shaped spring portionB can be made as a single integral piece of composite material.

As illustrated in, the V-shaped spring portionB can be provided inside the shoetoward the heel portion or the back sole portionB. In another embodiment, as illustrated in following figures (e.g.,) and described further in the following paragraphs, the V-shape portionB can be provided outside the shoetowards the heel portion or the back sole portionB. In this case, the lower platform portionof the V-shaped spring portionB is configured to contact the ground and the raised springboard portionis configured to contact the back sole portionB at the exterior of the sole(for example, as shown infor the V-shaped spring).

In an embodiment, the shoemay further include the fulcrum. The fulcrumcan be made from a flexible material such as rubber or other compressible plastic. In an embodiment, the fulcrumis provided at the mid-point of the sole. The fulcrumis configured to facilitate shifting of the weight of the wearer from the back to the front to sequentially accelerate the shifting of weight between the springs and the movement of the foot in leaving the ground. The fulcrumcan have a cylindrical shape. The fulcrumcan have a cylindrical diameter between about 0.5 inch and 1 inch, for example 0.75 inch. The fulcrumcan be fastened to the soleusing one or more fastenersA (e.g., fastened to an exterior surface of the sole, or attached with an adhesive). The one or more fastenersA can be screws or clips, etc. In an embodiment, the shoecan include the fulcrumduring the manufacturing of the shoe. In another embodiment, the shoecan be adapted to receive the fulcrumafter manufacturing of the shoe. Hence, the fulcrumcan be sold separately from the shoeor be attached to a composite material (e.g., a carbon graphite reinforced material) plate that also includes the front spring, and any shoe can be adapted to receive the fulcrum.

As shown in, the shoemay also include a front springdisposed at the front portion of the sole. The front springcan be made of resilient composite material such as a carbon graphite reinforced material. In an embodiment, the front springcan have a U-shape (or an open Bobby pin shape) with an open portionA of the U-shape oriented forward relative to the shoe. In an embodiment, the front springhas a shape that is similar to a “Bobby pin” shape. The front springhas a bottom portionB. The bottom portionB is configured to stretch or bend under an applied force (e.g., a force applied by the weight of person wearing the shoewhen the weight shifts forward onto the ball of the foot) and snaps back as the foot leaves the ground. The front springhas a top portionC. The top portionC an exterior surface of the soleof the shoe. The top portionC has a shape that substantially follows the shape of the soleat the front portion of the sole. In an embodiment, the top portionC of the front springcan be longer than the bottom portionB of the front spring. For example, the top portionC can be longer than the bottom portionB by about 1 inch to 1.5 inches. The front springmay be similar to the front springshown in.

Therefore, there is provided a front springfor a shoeand/or adapted to be mounted to any shoe. The front springincludes the top portionC configured to contact the soleat a front of the shoe. The front springalso includes a bottom portionB connected to the top portionC, the bottom portionB configured to stretch and deform under an applied force and to snap back when the applied force is released. The top portionC and the bottom portionB form a U-shape and an open portion of the U-shape is oriented forward relative to the shoe. The front springis configured to be disposed at the front portion of the sole, the front springbeing made of resilient material. In an embodiment, the resilient composite material comprises a flexible stiff carbon graphite. In an embodiment, the U-shape includes a Bobby pin shape. In an embodiment, the force comprises at least a portion of a weight of a wearer of the shoe. In an embodiment, when the weight shifts forward onto the ball of the foot, the bottom portionB snaps back as the foot leaves the ground. In an embodiment, the top portion has a shape that substantially follows a shape of the soleat the front of the sole. In an embodiment, the bottom portionB is curved to provide a spring recoil effect. In an embodiment, the top portionC is longer than the bottom portionB. In an embodiment, the top portionC is longer than the bottom portionB by about 1 inch to about 1.5 inches. In an embodiment, the width of the bottom portionB is greater than the width of the shoe, for example by about 0.25 inch. The top portionC may be a part of a flexible stiff composite material (e.g., a carbon graphite reinforced material) plate that extends past the back of the fulcrum, as shown in. This plate can be bent in front of the fulcrumas the heel is raised by the shoe springso that pressure is amplified on the front spring. There may be provided a slight raise inside the shoeabove the fulcrumto support the arch of the foot.

In an embodiment, a springboard linkmay also be provided between the front springand the fulcrum. The springboard linkmay further enhance the spring recall of the shoeafter bending of the shoeduring running.

In an embodiment, the shoe springmay also include a springboard fulcrumto adjust the stiffness of the raised springboard portion. The springboard fulcrumcan be provided in the V-shaped spring portionB of the shoe spring. For example, the springboard fulcrumcan be attached to the raised springboard portion, as shown in. Alternatively, this springboard fulcrumcan be attached to the lower platform portion. The springboard fulcrumcan be slidable to adjust a distance between the springboard fulcrumand the intersection point. Alternatively, the springboard fulcrumcan be placed at a desired position by the user. When the raised springboard portionmoves closer to the lower platform portion, the springboard fulcrummeets the lower platform portion. As a result, the recoil force of the raised springboard portionis increased propelling the heel of the foot of the wearer forward. The springboard fulcrumcan be slidable to adjust a distance between the springboard fulcrumand the intersection pointto adjust a spring constant of the shoe springto change the recoil force of the raised springboard portion, depending on a weight of the wearer, for example. The greater the distance between the springboard fulcrumand the intersection point, the greater is the recoil force of the raised springboard portion. The springboard fulcrumcan be made, for example, from a resilient material such as a rubber or a plastic.

The V-shaped spring portionB of the shoe springcan be sold alone for mounting to shoe or sold as a kit with the front springand/or the fulcrum. The shoe springmay also be sold as the V-shaped spring portionB and having the curved portionC with or without the springboard fulcrum.

is a perspective view of a shoe having a V-shaped spring, according to yet another embodiment of the present disclosure. The shoeshown inis similar in many aspects to the shoeshown in. Therefore, the description of similar features will not be repeated. It is noted, however, that the shoediffers from the shoein some aspects. For example, the lower platform portionof the V-shaped spring portionB of the shoe springhas a sleeve. The sleevecan be made from a cloth or other polymer or composite material that does not stretch. The sleevecan be provided the shoeand attached to the sole of the shoeto allow sliding in or removing of the V-shaped spring portionB of the shoe springfrom the shoe.

The top portionC may be a part of a flexible composite material (e.g., a carbon graphite reinforced material) plateD that extends past the back of the fulcrum, as shown in. The flexible composite material plateD can be bent in front of the fulcrumas the heel is raised by the shoe springso that pressure is amplified on the front spring.

is a perspective view of a shoehaving a front spring and a back spring, according to another embodiment of the present disclosure. The shoeis shown as being transparent to show the position of a wearer's footinside the shoe. The shoecomprises a lower portionincluding a solefor supporting the footof the wearer and an upper portionfor covering the footof the wearer. The soleincludes a front sole portionA for supporting the ball and toes of the footof the wearer and a back sole portionB for supporting the heel of the footof the wearer. In an embodiment, the shoeincludes a back springand a front spring. The shoealso includes a fulcrum.

In an embodiment, the back springand the front springcan be made from a resilient material including, for example, a composite material such as a flexible carbon graphite reinforced material. The resilient material of the back springand the front springcan be selected according to desired spring properties and according to a weight of the wearer. For example, the shoehaving the back springand the front springcan be rated and sold to support a certain weight, for example, by stating “shoe supports wearers with a weight between 120 lbs and 160 lbs,” or “shoe supports wearers with a weight between 170 lbs and 200 lbs,” etc. In another embodiment, the back springand the front springcan be changeable to accommodate the weight of the wearer. Hence, the back springand the front springcan be sold as a kit separately from the shoe.

In an embodiment, as shown in, the back springand the front springinclude a curved plate. A back endB of the front springis connected to the fulcrum. A front endA of the back springis also connected to the fulcrum, for example, glued or fastened using an appropriate fastener. A front endA of the front springis spaced apart from the front sole portionA. The back endB is spaced apart from the back sole portionB. In an embodiment, the shoealso includes a strike plate. The strike plateis coupled to the front sole portionA. the strike platecan be made of composite material, plastic, metal, or the like.