This application incorporates by reference, and claims priority to and the benefit of, German patent application serial number 10112821.5, titled xe2x80x9cShoe Sole,xe2x80x9d which was filed on Mar. 16, 2001.
The present invention relates to a cushioning system for a shoe using foam components having different shapes and densities.
When shoes, in particular sports shoes, are manufactured, one objective is to restrict the movements of a wearer of the shoe as little as possible. On the other hand, the different loads that arise on the skeleton and the muscles during running should be moderated to reduce fatigue or the risk of injuries under long lasting loads. One cause of premature fatigue of the joints or the muscles is the misorientation of the foot during a step cycle. Typically, professional athletes run exclusively on their forefoot, in particular during track and field events; however, the average amateur athlete first contacts the ground with the heel and subsequently rolls-off using the ball of the foot.
Under a correct course of motion, most athletes perform a slight turning movement of the foot from the outside to the inside between the first ground contact with the heel and the pushing-off with the ball. Specifically, at ground contact, the athlete""s center of mass is more on a lateral side of the foot, but shifts to a medial side during the course of the step cycle. This natural turning of the foot to the medial side is called pronation. Supination, i.e., the turning of the foot in the opposite direction, as well as excessive pronation, can lead to increased strain on the joints and premature fatigue or even injury. Therefore, when designing shoes, in particular sports shoes, it is desirable to precisely control the degree of turning of the foot during a step cycle in order to avoid the above-mentioned misorientations.
There are a number of known devices that influence pronation. For example, supporting elements may be placed in the midfoot and the forefoot areas of a sole to avoid excessive turning of the foot to the medial and/or to the lateral side during push-off. Typically, the heel portion of these soles is a simple cushioning element serving only to absorb the arising ground reaction forces. This approach, however, fails to recognize that the first phase of a step cycle influences the later course of motion of the foot. When the foot terminates the ground-contacting phase in the correct orientation prior to transitioning to the pushing-off phase, an essential requirement for an overall correct course of motion is obtained.
It is, therefore, an object of the present invention to provide a shoe sole that leads to a correct orientation of the foot starting from the first ground contact, thereby reducing or eliminating premature fatigue or wear of the joints and the muscles.
The invention generally relates to a cartridge cushioning system that incorporates a cushioning element to protect the joints and muscles of an athlete against the ground reaction forces arising during a first ground contact and at least one guidance element having a material property that assures that immediately after ground contact (and not only in the later phase of the step cycle) pronation control takes place, thereby bringing the foot into an intermediate position, which is correct for this stage of the step cycle. In a shoe sole having two guidance elements, for example a lateral and a medial guidance element, the combined effect of these two elements during ground contact is to control the transition of the center of mass of the load from the lateral rear side to the center of the heel.
The system further includes a load distribution plate in the heel region that facilitates uniform force distribution on the athlete""s heel and evenly transmits the cushioning and guiding effects of the above-mentioned elements to the complete heel region and not just to single parts of the heel. Further, the load distribution plate may supply stability and support to the heel region of the shoe. An optional stability element can be included in the cartridge cushioning system. The stability element can have a material property that helps prevent excessive pronation during transition into the rolling-off phase of the step cycle.
Generally, the functional elements of a cartridge cushioning system in accordance with the invention provide for the complete pronation control of the athlete""s foot, starting from the first ground contact until the transition to the rolling-off phase. Specifically, after compression of the cushioning element during the first ground contact, diagonally arranged guidance elements guide the center of mass of the load to the center of the heel. An optional stability element arranged in the medial front area of the heel assures that the center of mass does not excessively shift to the medial side in the course of a further turning of the foot.
In one aspect, the invention relates to a sole for an article of footwear. The sole includes a load distribution plate disposed in a heel region of the sole, a cushioning element disposed proximate the load distribution plate, and a guidance element disposed proximate the load distribution plate. The cushioning element is configured and located to determine a cushioning property of the sole during a first ground contact with the heel region. The guidance element is configured and located to bring a wearer""s foot into a neutral position after the first ground contact.
In another aspect, the invention relates to an article of footwear having an upper and a sole attached thereto. The sole includes a load distribution plate disposed in a heel region of the sole, a cushioning element disposed proximate the load distribution plate, and a guidance element disposed proximate the load distribution plate. The cushioning element is configured and located to determine a cushioning property of the sole during a first ground contact with the heel region. The guidance element is configured and located to bring a wearer""s foot into a neutral position after the first ground contact.
In various embodiments of the foregoing aspects, the sole includes a second guidance element disposed proximate the load distribution plate. The second guidance element is also configured and located to bring the wearer""s foot into the neutral position after the first ground contact. The sole can also include a stability element disposed proximate the load distribution plate. The stability element is configured and located to avoid excessive pronation during transition to a rolling-off phase of a step cycle.
In various embodiments, the cushioning element is generally located in a lateral rear quadrant of the heel region, the guidance element is generally located in a lateral forward quadrant of the heel region, the second guidance element is generally located in a medial rear quadrant of the heel region, and the stability element is generally located in a medial forward quadrant of the heel region. Further, the cushioning element, the guidance element, the second guidance element, and the stability element are spaced apart. In one embodiment, the elements can be spaced equidistantly apart. The sole may include at least one reinforcing element disposed between at least one of the cushioning element and the guidance element, the guidance element and the second guidance element, the second guidance element and the stability element, the stability element and the cushioning element, the cushioning element and the second guidance element, and the guidance element and the stability element.
In additional embodiments, at least one of the guidance element, the second guidance element, and the stability element has a greater hardness than the cushioning element. In addition, the hardness of at least one of the guidance element, the second guidance element, and the stability element may vary, for example, by increasing from a rear portion to a front portion thereof. In one embodiment, the stability element may extend beyond an edge of the load distribution plate. In another embodiment, the load distribution plate may have a generally recumbent U-shaped cross-sectional profile and can at least partially circumscribe at least a portion of one of the cushioning element, the guidance element, the second guidance element, and the stability element. The closed end of the load distribution plate may be oriented towards a forefoot portion of the sole. The sole may also include an outsole at least partially disposed below the cushioning element, the guidance element, the second guidance element, and the stability element.
In yet another aspect, the invention relates to an article of footwear including an upper and a sole attached thereto. The sole includes a load distribution plate disposed in a heel region of the sole, a cushioning element disposed proximate the load distribution plate, a first guidance element disposed proximate the load distribution plate, a second guidance element disposed proximate the load distribution plate, and a stability element disposed proximate the load distribution plate. The cushioning element is generally located in a lateral rear quadrant of the heel region and is configured to determine a cushioning property of the sole during a first ground contact with the heel region. The first guidance element is generally located in a lateral forward quadrant of the heel region and is configured to bring a wearer""s foot into a neutral position after the first ground contact. The second guidance element is generally located in a medial rear quadrant of the heel region and is configured to bring the wearer""s foot into the neutral position after the first ground contact. The stability element is generally located in a medial forward quadrant of the heel region and is configured to avoid excessive pronation during transition to a rolling-off phase of a step cycle.
These and other objects, along with advantages and features of the present invention herein disclosed, will become apparent through reference to the following description, the accompanying drawings, and the claims. Furthermore, it is to be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and permutations.