Exercise and fitness system

This is a continuation-in-part of U.S. patent application Ser. No. 11/450,114, filed Jun. 9, 2006, which is hereby incorporated by reference

The use of exercise machines has proliferated in the last decade or so. In general there are two main classifications of such machines—those primarily intended for use in a commercial sports center and those primarily intended for use in the home. Those intended primarily for use in a sports center are quite complex, are structurally heavy and bulky, are usually attached to the floor or the wall, and oftentimes have a complicated arrangement of levers, pulleys, weights, etc. Normally they may also be adjustable for different users having different physical strengths. Those intended primarily for the home are simpler, lighter, much less expensive but still adjustable to some degree.

One such exercise machine comprises flexible elastic shock cords, usually two, which are stretched by a force exerted by the user. As a cord is stretched more and more, the force required to stretch it increases more and more. One end of the shock cord is attached to a fixed structure and the other end attached to a booster bar adapted to be moved by the user\'s arms or legs as the cord is stretched by the user. As a natural consequence of the size of the user the stretched length of the shock cord will be substantially constant for a given user but will be different for a different user. Also as a natural consequence of the physical characteristics of shock cords the force-length curve is an inverse exponential when the force is displayed as the abscissa. Thus the maximum force required for a given user to stretch his arms or his legs to their fullest extent depends on the characteristics of the shock cord and also on the ratio of the stretched length to the unstretched length of the shock cords. Since a different user having a different physical size or strength will require a different ratio of stretched length to unstretched length it becomes necessary to provide some means for shortening or lengthening the unstretched length. This is normally effected by means of clamps; however the clamps oftentimes damage the shock cord and thus make the shock cord essentially unusable after a given number of adjustments.

In U.S. Pat. No. 5,125,649, to Conrad Fuller (Fuller) (incorporated hereby by reference) is an exercise machine with a booster bar that mitigates the problems of adjustment found in previous systems, where the stretched and unstretched length of the shock cord are adjusted by the user without the use of clamps or tools. In the Fuller system a booster bar is attached to pair of flexible elastic shock cords, which have their other ends attached to fixed structural members. The user exercises his arms or his legs by repeatedly pushing against the booster bar, thus stretching and unstretching the shock cords. The unstretched (and thus the stretched) length of the shock cords is adjusted by rotating the booster bar about its axis, thus winding or unwinding, the shock cords around the booster bar. This, in turn, adjusts the force required to stretch the shock cords to a given dimension.

However, the Fuller system is still not adequate in providing an exercise machine that can be used by different users of different size and with different strengths. This is due to the nonlinear force-length properties of braided shock cords, which as mentioned in the Fuller patent can be represented as an inverse exponential curve. Basically as the cord is stretched, the stretching or return force is approximately constant or increases proportionally at a modest rate. But, as the maximum stretching length for the cord is approached, the return force increases much more rapidly, where (at least as perceived by the user) even significant increases in the force will not cause the cord to stretch further. Thus, the perceived effect by the exerciser is a movement that is suddenly or abruptly stopped. In other words, as the cord is stretched, the user at first perceives a constant or modest increase in force as determined by the stiffness of cord until a point is reached where the stretching or return force increases rapidly with no or little increase in the stretching length. At this point the exerciser perceives an abrupt stop and cannot continue extending the cord.

Basically, a braided shock cord will extend, depending on the particular cord construction, up to 100% or more of its unstretched length, until it reaches a this “abrupt stop” point where under higher and higher forces it will stretch only a small amount.

As described in the Fuller patent, the length of the shock cords can be adjusted by wrapping them around the booster bar. However, when fully unwound to lengthen stretching cord and allow the user to stretch the cords a greater distance before reaching the abrupt stop, the initial force and the force over the most of the length of the stretching is also reduced, which reduces the exercise effect. To increase the force and the exercise effect, the stretched length of the shock cord can be shortened by wrapping the cord around the booster bar. But if the stretching length is shortened too much this will prevent the user from extending the cord to the length required for the exercise. This is because the user is attempting to stretch the shortened shock cord beyond its design and the “abrupt stop” is encountered before the exercise movement is completed.

A partial solution is to use shock cords of different elastic, i.e., stiffness, properties. “Stiffness” or “stiff” is a measure of the amount of elastic return force obtained for a given amount of stretching. For a strong person, a machine with stiffer cords is chosen so that the stretching force is high at the beginning during the stretch. Because the cord does not have to be shortened excessively, and the abrupt stop isn\'t reached during exercise movements, the person is allowed to stretch to the desired length for the exercise. A weak person could not use such a machine, because, even when the cords are fully unwound to the full length, the stretching force is too high, and he would only be able to successfully accomplish few or none of the exercises. For the weak person, a machine with less stiff or compliant shock cords would be suitable. However, the strong person would not find this machine suitable, because she would be able to extend the cords as far as she can extend her limbs without feeling adequate increase in the stretching force. Winding the cords around the booster bar to increase the force, may result in insufficient stretching length where the abrupt stop will likely be reached during routine exercises. Exercises with long stretches then become difficult or impossible.

In summary, the Fuller machine has the ability to change the stretching length of the shock cord, which enables a person to vary the stretching force and to do a variety of exercises, from short stretches to long stretches. But, the advantage is not fully met if the stiffness of the shock cords does not well match with a user\'s size and strength. This is a particular problem as the user becomes stronger over time, requiring the user to obtain a new machine or rebuild the old one.

An aspect of the present system is an exercise apparatus comprising a rigid booster bar with two flexible elastic elements attached to the booster with an attachment. The attachments are spaced from each other and configured to allow winding the elastic element upon the booster bar by rotating the booster bar. Each flexible elastic element comprises at least two stages of flexible shock cords, with the stages disposed serially along the length of the flexible element, with adjacent stages having a different elastic stiffness.

Another aspect of the present system is an apparatus that improves upon the Fuller machine by extending the range of user size and strength that can be matched to a particular apparatus. Any one apparatus is optimal for a wider range of user size and strength. The apparatus of the present system can be used like the Fuller machine, by stretching and unstretching flexible elastic elements by means of a booster bar, and the user can change the stretching length of the elastic elements by wrapping same upon the booster bar. However, the present apparatus has replaced the shock cords in Fuller machine with improved flexible elastic elements that have a more optimum force-length curve. In addition, the apparatus of the present system, because of its unique construction, can be used in different ways.

The improved elastic elements can be wound and unwound upon the booster bar to adjust force, but with a small or minimal amount of winding required to obtain a higher stretching force. This leaves a larger stretching length and lessens the probability that the abrupt stop will be reached during an exercise movement. The cord can be stretched to high stretching forces without encountering an abrupt stop, even in exercises requiring high force and a long stretch.

Not only is the abrupt stop essentially eliminated, but the force-length profile is improved. During a stretch, higher forces are obtained at a slower rate. In addition, the stretching force encountered in an exercise movement is over a wider range, allowing a user to start the stretch at a lower force and stretch up to and sustain a higher force, a force that cannot be sustained if the high force comes on quickly or abruptly. This allows a user to sustain higher forces and gain more strength building benefit than in previous devices. In previous devices, one could not gradually obtain a high stretching force when starting a low stretching force, because the abrupt stop would be reached before the high force was obtained.

In addition, for any given apparatus a stronger user will be able to derive more exercise and obtain and sustain higher forces, and a weaker user has lower forces available that allows accomplishment of more exercises. Both weaker and stronger users benefit from the better force-length profile. Thus, it is possible by practice of the present system that a single apparatus can be provided that better meets the needs of a person as he grows stronger, and be more easily adjusted for wider variety of people, including children, adults, athletes, sedentary persons, and persons with physical disabilities.

The apparatus of the present system achieves the above advantages in part by having a rigid booster bar with a flexible elastic element constructed with multiple stages of braided elastic stretch cords attached to each end. By “staged”, is meant that the length of each stretch cord is subdivided into at least two regions or stages. Each stage is constructed with one or more braided shock cords, such that each adjacent region has a different stiffness from its neighboring or adjacent stages. Thus the stages are attached in series end to end such that the stiffness of the elastic element changes from stage to stage. This contrasts with the Fuller machine where the elastic cords are designed with essentially the same stiffness for their entire length.

Because the flexible elastic element is staged, with high stretch force a high elongation can be obtained without encountering an abrupt stop. This is in part to the fact that the large stretching forces can be obtained with a minimum of wrapping around the bar, allowing more of the length of the elastic element to be stretched.

In addition, as the flexible element is stretched, the lengthening or elongation is not distributed evenly along its length. During a stretch all of the stages will begin to elongate, but the less stiff stages will initially stretch more than the stiffer stages. As the less stiff stages approach their maximum elongation, more elongation will then occur in stiffer stages. Thus, elongation is serially transferred from the less stiff stages to the stiffer stages, with the stiffest stages being the last to sustain significant elongation. The stiffest stage is designed to sustain the maximum design force of the equipment without reaching its maximum elongation required for exercise. Thus, at any elongation during exercise, there are always one or more stages that have not reached maximum elongation, thus eliminating an abrupt stop.

Furthermore, at the beginning of the stretch the force is mostly determined by the least stiff or most compliant stage, but the elastic element can be stretched to a high final force as determined by the stiffest stage. By the staged system a rather even force profile can be provided that extends from a low stretching force of stiffness to a stiffness, and this profile can be predetermined by the selection of different stiffnesses of multiple stages.