BACKGROUND OF THE INVENTION
-
When playing racket sports or sports using clubs or bats, correct form is essential, whether it be tennis, ping-pong, golf, badminton or baseball. Unless the correct forms can consistently be achieved, proficiency in these kinds of sports will never result. For example, if the form is wrong, it is impossible to hit a strong, well-controlled shot in tennis. In addition, it is difficult to respond quickly and effectively to balls hit by the rival.
-
Up until now, the way to master the correct forms has been to learn from a trainer or painstakingly practice the patterns outlined in books and related literature. In golf, form-correcting aids have been developed. However, these have not proved to be entirely effective, and cannot be transferred to other sports. As a result, it has generally been difficult to master the correct forms.
-
It is important to recognize some of the specific obstacles to correct form in racket sports or sports using clubs or bats. Tennis will be considered as an example.
-
In tennis, consider the case where a right-handed player is going to hit a forehand ground stroke. Most beginners instinctively extend their arm out to the side in order to connect perpendicular to the ball's direction. In doing so, because the movement of the upper arms is not fixed relative to the shoulders, the ball is hit with only the force of the right arm, and the twisting of the body that ought to create the power behind the shot is not transmitted to the ball. As a result, the ball is not hit with adequate strength or control.
-
In volleying the problem is compounded because the impact point is behind the player's line of sight, making it impossible to see the ball at the time of impact. Control suffers significantly and it becomes difficult to connect at the middle of the racket face.
-
When hitting a backhand ground stroke, again the tendency is for the arms to move freely relative to the shoulders. As a result the angle between the arm and the chest is too sharp and the ball is hit only by the force of the arm. Furthermore, because beginners tend to move the upper and lower parts of their body separately, when moving to hit the ball their balance suffers and their shot is compromised.
-
Playing sports like tennis with bad form, results not only in poor performance, but also in physical injury
DETAILED DESCRIPTION OF THE INVENTION
-
The key to achieving correct form and good body control in most sports is to have all skeletal muscles in a state of uniform alertness, with the movement of the back fixed relative to the pelvis, and the addiction and diction of the upper arms restricted. In addition, it is important to have the body's centre of gravity balanced in the middle of the portion of the feet which makes contact with the ground. As will be described in what follows, it is difficult to achieve this ideal body condition with shoes sold commercially today. Therefore, it takes much time and effort to develop competence in these sports. The invention of the applicant's form-correcting shoes is intended to allow someone to naturally achieve this ideal body condition.
Restricting the Addiction and Diction of the Upper Arms
-
Restricting the addiction and diction of the upper arms forces the movement of the arms, shoulders and chest to remain fixed relative to each other.
-
Consider again the right-handed tennis player preparing to hit a forehand ground stoke. As the right hand draws the racket backwards, because the movement of the upper arm is fixed relative to the chest, the right shoulder and right part of the chest are forced to move together with the right arm. Simultaneously, the left part of the chest and left shoulder are also forced to turn to the right side. With this movement, only the left shoulder is seen from the front. When the ball makes impact, the motion is initiated from the right chest, transferred to the right shoulder and in turn to the arm and ultimately the ball. This is exactly the form required to achieve power and good ball control. Because the movement of the upper arms is fixed relative to the chest, the player cannot make the mistake of hitting the ball merely supported by the force of the right arm moving independently.
-
Similarly, in hitting a volley, the movement is the same as hitting the forehand ground stroke, but the swing is smaller. Because the arms are forced to make an angle of about 60° relative to the chest, the point of impact is in front of the player. Therefore, the player can see the ball impact the racket and better ball control results.
-
With the backhand ground stroke, as the player brings the racket backwards, the right chest is forced to move to the left until the right shoulder hides the left shoulder, and the motion to hit the ball is again initiated from the chest and then transferred through the shoulders and arms as described above. The right chest serves as a base for the right hand so that the spinning force of the body can effectively transfer to the right arm and ultimately to the ball. Again, this action cannot be achieved if the arms move freely relative to the chest.
Fixing the Movement of the Back Relative to the Pelvis
-
Effectively transmitting the force of the twisting body to the shoulders, arms and ultimately the racket, or club or bat as it may be, is a major factor in developing proficiency in many sports. The main muscles in the abdomen and back which effect the power of the twisting body, originate in the backbone and pelvic area. In order to effectively create this twisting motion in the body, it is necessary to fix the motion of the backbone relative to the pelvis at the joint between the sacrum and the fifth lumbar vertebra. When the movement of this joint is not fixed relative to the pelvis while twisting the body, part of the force will be needlessly dissipated because of the counter-swing of the buttocks.
-
With the addiction and diction of the upper arms restricted and the movement of the backbone fixed to relative to the pelvis, the arms, shoulders, chest, waist and legs are forced to move in unison with each other and thus achieve the desired athletic form.
-
Consider the case of a right-handed player preparing to hit a forehand ground stroke. When the racket is pulled back, the arms and shoulders will move in unison as described above. At the same time, because the vertebral column is stiff, when the right side of the chest is moved backwards, the right thigh and leg will simultaneously turn so that the right foot becomes perpendicular to the direction of the ball. With the right foot in this position, the force of the leg pushing the ground will effectively transfer to the ball. Since the movements of both the body upper and lower parts are in tandem with each other, the player can quickly and strongly respond to the movement of the ball.
Balancing the Body's Centre of Gravity
-
Maintaining good balance during play is a key element to effectiveness in any sport. To achieve this, in addition to fixing the motion of the backbone relative to the pelvis, and the upper arms relative to the shoulders, it is important that all skeletal muscles in the body be uniformly alert, so that the body is balanced while generating a spring-like action. If some muscles contract too acutely while some muscles do not contract enough, the response to the ball will be delayed and the player will not hit the ball with the desired effect. In addition, the body's centre of gravity should always be balanced in the middle of the portion of the feet which makes contact with the ground, otherwise the balance will be affected during movement and ball control will suffer.
The Problem With Traditional Shoes
-
Currently, not only sports shoes, but almost all shoes, are designed so that the heel is positioned higher than the toe and the ball of the foot. It is the claim of the applicant, that this aspect of traditional shoe design is one of the primary obstacles to achieving the correct form and body control essential to competence in many sports.
-
When someone stands straight on level ground while wearing shoes with a heel elevation above the elevation of the toe and ball of the foot, the body's centre of gravity is not in the middle of the foot but nearer to the heel. As a result, when the body twists, the tendency will be for the shoulders to rotate more than 90 degrees from centre and the upper arms to rotate even more. This is because the centre of the body is twisting at a point higher than the joint between the sacrum and the fifth lumbar vertebra and the adduction and abduction of the upper arms is not suppressed, that is, the motion of the upper arms is not fixed relative to the shoulder. In this condition, when the body moves to the left or to the right, the hips and buttocks will move conversely in order to compensate. The compensating movement of the hips and buttocks unnecessarily dissipates the power generated by the body's twisting motion. In addition, when walking or running, the heel will often make contact with the ground before the ball of the foot or the toe portion.
-
As such, the body's centre of gravity moves on two planes of the foot, i.e., from the plane running from the heel to the ball of the foot, to the plane running from the ball of the foot to the toes. As the alternating motion of the feet transfer the body's weight in motion, the centre of gravity transfers from the surface of the ball and toe portion of one foot to the surface of the heel and the ball of the other foot. As a result, the centre of gravity bobs up and down with each shift from one foot to the other and this in turn causes loss in the strength and control of the ball. Furthermore, since the motion of the upper arms is not fixed relative to the shoulders, the force of the body's twisting motion cannot be effectively transferred to the arm. For these reasons, it is not easy to develop proficiency in tennis and other sports while wearing shoes with the heel elevated above the toe.
How Professional Tennis Players Compensate
-
Somebody may question why professional tennis players have developed proficiency despite using these traditional shoes. The answer is that although they are no doubt unconscious of the mechanics involved, they have learned to play with their heels raised, standing on the toes and balls of their feet so that the body's centre of gravity is evenly balanced. This in turn helps fix the motion of the backbone relative to the pelvis and the upper arms relative to the shoulders. With no energy dissipated from a compensating movement in the hips and buttocks, when the body twists it acts like a spring, and a powerful, controlled force results.
-
When in motion, the body's centre of gravity will transfer from the surface of the toe and ball of the foot to the same surface on the other foot, thus the height of the body's centre of gravity remains level and there is no energy dissipated in an up and down bobbing motion when transferring from one foot to the other.
-
The problem with this method of playing tennis, is that players have to intentionally stand on the toes and ball of their feet. Learning how to naturally play standing on the toes, in order to achieve the balance and spring-like body action that results from it, takes a tremendous amount of time and practice. And because the size of the toe portion of the foot is not large, players need to keep shifting their weight while they are waiting for the ball. This is the reason why many professionals still find it difficult to do hit effective drop shots.
A Discovery Concerning The Role of the Foot's Position
-
At the heart of the applicant's invention, is the realization that when a person stands on straight on level ground with their toes raised, the body's centre of gravity falls evenly between the heel and the ball of the foot. In addition, the elevation of the toes causes the skeletal muscles to tense into an alert condition and the movement of the backbone is fixed relative to the pelvis, and the upper arms relative to the shoulders. This is exactly the body condition required to achieve a strong, controlled spring action in the body when playing tennis and other such sports. These benefits will result automatically as long as the distance between the feet is not larger than the width of the pelvis.
-
The applicant's claim can be verified by standing straight in bare feet on a level surface with the toes completely lifted up. From this position, i.e. with no body weight on the toes, and the feet resting on the ground, when the body twists, it can be seen that the shoulders will rotate only to about 60 degrees from the centre and the upper arms will not rotate past the shoulders. Also, when walking or running with bare feet on a level surface with the toes lifted up, the heel and the ball of the foot will connect with the ground almost simultaneously and the body's centre of gravity will remain in the middle of the plane stretching from the heel to the ball of the foot and the toe will never bear the weight of the body.
-
As described above, with the body in this condition, it is easy to play tennis with correct form and good body control. However, even if the heel and the ball of the foot are at the same height, if the toes bear weight for any reason, the natural spring action sought from the twisting of the body is immediately lost. This can be verified by twisting the body while standing straight on level ground in bare feet with the toes touching the ground, or while standing straight on level ground with only the toe portion of the foot touching the ground. It can be seen with the toes touching the ground in this way, the movement of the forearms is no longer fixed relative to the shoulders and thus the forearms can be rotated well beyond the shoulders.
A New Approach to Shoe Design
-
Based on above discovery, the applicant has designed form-correcting shoes which eliminate the weight borne by the toes, and balance the center of gravity evenly between the heel and the ball of the foot. By wearing these form-correcting shoes, the skeletal muscles will naturally tense into a state of uniform alertness, the movement of the backbone will be fixed relative to the pelvis, the movement of the upper arms will be fixed relative to the shoulders, and the correct form required for achieving proficiency in many sports will be far more easily mastered.
BRIEF DESCRIPTION OF THE DRAWINGS
-
- Figure 1 is a cross-section of the form-correcting shoes.
- Figure 2 is a cross-section of the form-correcting shoes with the portion of the sole under the toes removed.
THE BEST FORM TO ACHIEVE THE INVENTION
-
The applicant's design has been tested by raising the height of the ball of the foot to that of the heel using cotton inserts. Playing tennis with traditional shoes modified in this fashion eliminates the load borne by the toes.
-
Specifically, 26.5 cm Adidas tennis shoes with a traditional sole construction were used. As can be seen in fig. 1, with these shoes, the heel (1) is higher than the ball of the foot (2) and the toe (3). The ball of the foot was raised using a cotton cloth insert (5) to the height of the heel, which was approximately 2.5 cm high. The cloth was inserted at the point where the toe intersects with the foot and was designed in such a way as to raise the toes and create a recess that would allow the toes to be suspended freely. These shoes were originally designed to have the base surface of the shoe curve up from the ground from the ball of the foot to the edge of the toe at an angle (c) of more than 7 degrees.
-
Having the height of the toe significantly lower than that of the heel and the ball of the foot, together with having the bottom surface of the toe part curved up from the ground are important to eliminate the load borne by the toes. That is, only the plane that runs from the ball of the foot to the heel supports the body's weight, not the plane running from the ball of the foot to the toe. If the curvature of the bottom of the shoe in the toe portion is inadequate, the toes will connect with the ground and bear the body's weight at the point of transition from one foot to the other, causing an overall loss in balance.
-
In the case of shoes where the heel and the ball of the foot at the same height, as long as that height is adequate, the portion of the shoe's sole under the toes can be eliminated as in figure 2. This is because, as the body weight is shifted from one foot to the other, the heel of one foot rises, the ball of that foot connects with the ground, and then the heel of the other foot lands on the ground, completing the cycle involved in walking or running. In this cycle of movement, even with the toe portion of the sole eliminated, the toes will not touch the ground, as long as the heel and the ball of the foot are raised to an adequate height.
-
The applicant's form-correcting shoe invention specifies that the body weight borne by the toes is eliminated and the center of gravity remains balanced evenly between the heel and the ball of the foot, whether in a standing, walking or running position. The purpose of the form-correcting shoes is to achieve a body state whereby the motion of the backbone is fixed relative to the pelvis, the movement of the upper arms is fixed relative to the shoulders, and all skeletal muscles are in a uniformly alert condition. As such, shoes with minute differences (+/- 0.1 mm) in height between the heel and the sole, should not be considered as exceeding the specifications of the applicant's design, as long as they can be shown to help achieve the above body state. The permissible range of deviation however cannot be great. In tests for example it was shown that even a 1 mm difference in height between the heel and the ball of the foot, or the inner and outer part of the sole, was adequate to make the desired body state unachievable.
-
In order to raise the ball of the foot to the height of the heel, insole pads may be inserted to modify traditional shoes. For shoes with removable spikes such as those used in football, baseball and golf, longer spikes could be used at the ball of the foot to raise it to the height of the heel.
POSSIBLE INDUSTRIAL BENEFIT OF THE INVENTION
-
Wearing the form-correcting shoes of the applicant's invention automatically causes (a) the skeletal muscles to tense into a state of uniform alertness, (b) the motion of the forearms to be fixed relative to the shoulders, and (c) the motion of the backbone to be fixed relative to the pelvis. Through tests, it has been verified that wearing these form-correcting shoes significantly enhances the body's form, motion and control when playing sports such as tennis, as compared with traditional shoe designs.
-
In addition, when walking or running, the body's center of gravity remains balanced evenly between the heel and the ball of the foot and the load borne by the toes is eliminated. In other words, by using these form-correcting shoes, the player is forced to use only the surface of the foot from the heel to the ball of the foot and not the toes. Since this surface area is much larger than the toe portion, players can remain balanced on one foot for a longer time, and thus achieve better timing and hit stronger and better controlled shots than those who have to shift back and forth more frequently because they rely solely on the smaller and more easily fatigued toe portion.
-
Wearing shoes with the heel higher than the toe and the ball of the foot makes it impossible to maintain the center of gravity between the heel and the ball of the foot when in motion because the body weight will inevitably be transferred to the toes when shifting from one foot to the other.
-
Although tennis has been used as the primary example in this introduction, the obstacles to correct form caused by the elevated heel in traditional shoes create similar problems in other sports. For example, traditionally sprinters have relied heavily on the toes and the balls of their feet in running. This is because speed is sacrificed when the body weight is transferred from the plane connecting the ball of the foot and the heel, to the plane connecting the toe and the ball of the foot. This transfer also threatens proper balance. So in an effort to avoid this problem, the toe surface is used exclusively while running at full speed. However with the applicant's form-correcting shoes, it is possible to run at full speed using the surface of the foot between the heel and the ball of the foot. Compared with running using just the toe surface, the up and down bobbing motion of the body is greatly reduced, allowing the body's energy to be more efficiently directed towards moving the body forward. Moreover since this surface is much greater than that of the toe surface, the applicant's form-correcting shoes will provide stronger resistance to centrifugal forces, allowing the sprinter to run faster in corners without fear of falling.
-
While it has been shown that the applicant's form-correcting shoes make significant improvement on performance in short-distance running, the same can be said for long-distance walking competitions or marathons. Wearing traditional shoes, racers are forced to use the heel, toes and ball of the foot each time the body weight is transferred to the foot. With a ten or forty kilometer distance, it is impossible to rely exclusively on the toe surface as sprinters do. Since the body's center of gravity shifts in motion, unnecessary energy is extended to balance the body. Moreover, with traditional shoes, the movement of the backbone is not fixed relative to the pelvis, nor is the movement of the upper arms fixed relative to the shoulders. As a result, part of the body's energy is needlessly dissipated in the counter movement of the buttocks and arms.
-
The side to side movement of the buttocks is one of the distinctive features of competitive walking. But the energy loss created by this motion has a great negative effect in long-distance races. Racing time will be significantly reduced with a more efficient body motion. Each of these problems is addressed in the applicant's form-correcting shoes. The sideways movement of the hips and buttocks will be almost completely eliminated while walking at high speeds wearing these form-correcting shoes.
-
In summary, the applicant's form-correcting shoes help players play achieve correct forms especially in sports using rackets, bats or clubs. These form-correcting shoes are also suitable to be used for mountain climbing, walking, working, or even as slippers or sandals. People will find that the body state achieved by the form-correcting shoes will help alleviate falls, fatigue or muscular pain.
