US 20050279784 A1
An improved hydration system for runners that provides superior motion control. Fluid is contained within a flexible bladder and pack, and attached to the waist. The pack is constructed of comfortable, elastic, and thermally insulating fabric. When attached to the waist, tension in the fabric compresses the bladder against the user and dampens motion. Along with reduced thickness of the fluid-filled bladder, uniform distribution of fluid in the bladder contributes to motion control and is provided by placement of the zipper in a horizontal orientation across the lower portion of the pack. Additional stability is achieved by attachment of waist straps at angles above horizontal, thereby increasing tension across the top portion of the pack, preventing it from flopping away from the user's body.
1. A hydration system for runners comprising:
a) a waist pack formed by joining at least two sheets of elastic fabric about the perimeter, said sheets forming an outer layer and an inner layer of fabric, said layers defining an internal compartment;
b) a flexible bladder for containment of fluid, said bladder having a fluid holding capacity of between about 1 and 3 liters, and contained within the inner compartment of said waist pack;
c) said waist pack having an inelastic member attached to the front sheet, said inelastic member being placed in a horizontal orientation within the lower front portion of the pack, said lower portion being defined as being between 0.15 and 0.5 times the greatest vertical extent of said pack from the lowest vertical extent of said pack, resulting in motion control as a result of the inelastic nature of said member constricting said flexible bladder within the region of the inelastic member, resulting in a partial baffle effect and more even distribution of fluid in the vertical direction;
d) means for attaching said pack about the waist of the user, said means comprising straps attaching at their proximal ends to left and right side of said pack and being secured at their distal ends by buckles about the user's waist;
2. The hydration system of
3. The hydration system of
4. The hydration system of
5. The hydration system of
6. The hydration system of
7. A hydration system comprising a waist pack formed by joining apposed front and back layers of elastic thermally-insulating fabric, said fabric layers being joined about the perimeter and thus defining an inner compartment for containment of a flexible bladder for containing between about 1 and 3 liters; said bladder having a shape approximating that of an ovoid; means for attaching pack about the waist of the user, said means comprising straps or webbing attached to the lateral edges of said pack, said straps being oriented at an angle of between 15° and 60° above the horizontal axis of said pack, said orientation providing increased tension across the upper portion of said pack, said increased tension acting to draw upper portion of said pack and bladder firmly against the body of the user; an inelastic member sewn in a horizontal orientation across the lower front portion of said pack, said lower portion being defined as being between 0.15 and 0.5 times the greatest vertical extent of said pack from the lowest vertical extent of said pack.
8. The hydration system of
9. The hydration system of
This application claims the benefit of Provisional Patent Application Ser. No. 60/478,419, filed Jun. 16, 2003.
1. Field of Invention
This invention relates to the field of personal hydration systems used by runners or joggers.
2. Discussion of Prior Art
Running, cycling, and other forms of exercise produce an increased need for water intake to compensate for that lost by respiration, perspiration, and renal output. This need, if not met, may become life threatening during prolonged high-intensity activity in hot weather. It is therefore desirable to be able to carry on one's person an adequate supply of water or other hydrating fluid.
Although hydration systems are in common use by cyclists, prior art hydration systems for runners have not met one essential design criterion: The device must utilize a stable, non-irritating waist-mounted system with sufficient motion control to minimize bounce and sway. Manufacturers of back-mounted hydration packs have attempted to adapt these devices for runners so that they may be worn about the waist. These waist-mounted packs are essentially back-mounted designs retrofitted with a waistband, and are constructed without consideration of the unique needs of runners.
Because a cyclist has little oscillatory body motion compared to a runner, a back-mounted pack can be attached with loose shoulder straps. Furthermore, since there is little motion of the pack relative to the user's back, the pack can be constructed of inelastic woven nylon or polyester fabric. However, running produces substantial running-related movement of the muscles about the waist and hip area. To achieve sufficient motion control, the waistband must be cinched tight to prevent motion of the pack. However, as the tension of the waistband increases, so does the pressure on the user's muscles, tendons, and other tissues. As a result, the user of such packs is faced with a dilemma: if too loose, the pack will have too much motion, and if too tight, the result is discomfort and possible injury. Since the tissue of the waist area is in motion, the pack itself must be sufficiently pliant so that it can move with the runner. Inelastic fabric does not allow for this, and may represent a potential source of injury to runners who use such systems.
Another problem that arises with the use of inelastic cloth relates to the ability of the fabric to prevent motion of the bladder within the fabric pack. The basic design of all hydration packs is a bladder within a fabric bag or pack. When the pack is constructed of inelastic fabric, the maximum tension against the bladder is achieved only when the bladder is filled to the point where its volume is equal to the volume of the fabric compartment. As fluid is drained from the bladder, the volume of the bladder decreases, but the volume of the fabric bag does not. The bladder is thus free to bounce around, producing excessive motion of the system. Some systems utilize additional straps to take up the slack created by decreasing bladder volume; however, these must be continually tightened as the bladder is drained, and this is inconvenient.
Prior art hydration systems suffer from additional problems. Because of gravity and the flexible nature of the bladder, fluid pools in the bottom of the bladder. This produces an uneven distribution of the fluid within the bladder, producing sloshing as a result of the increased moment of inertia of the fluid within the bottom portion of the pack.
Given that hydration systems are most useful in hot weather, thermal insulation is essential to prevent fluid warming. However, prior art packs employ a design in which additional thermal insulation is sewn into the fabric pack, and this increases both the complexity and cost of construction. Ideally, the fabric used in construction of the pack would have a combination of the desired mechanical and thermal properties so as to provide both motion control and thermal insulation.
It can be seen that prior-art hydration systems for runners suffer from a number of problems, including:
Accordingly, several objects and advantages of the present invention include:
Other objects and advantages will become apparent from a consideration of the following description and drawings.
The following invention is a personal hydration system designed for runners and joggers, and consists of a flexible bladder to contain potable fluid. The bladder is enclosed in a flexible, elastic fabric pack and fastened about the waist of the user. The flexible fluid-filled bladder is restrained by compression against the user's body by the tensioned outer fabric layer of the pack. Because tension in the elastic outer fabric layer is maintained automatically as the bladder volume decreases with fluid consumption, compression of the bladder against the user's body is maintained at all times, providing constant motion control. In the present design, the zipper, in addition to allowing insertion of the bladder into the pack, also functions as a structural element. By placing the zipper in a horizontal orientation across the lower portion of the pack, the pack is unable to stretch in the region of zipper attachment. As a result, the zipper acts as a baffle, constricting the lower portion of the bladder and preventing excessive pooling of fluid within this region. This reduces the moment of inertia of the bladder within the lower portion, resulting in significant motion control. An additional structural feature involves the angle of attachment of the webbing that wraps around the waist of the user. Placement of the webbing at an angle above horizontal relative to the horizontal axis of the pack produces increased tension in the upper portion of the pack, preventing this portion of the pack from flopping away from the user's body, thereby increasing stability of the pack as a whole.
Two key features of the pack design contribute to motion control of the enclosed fluid-filled bladder. Because of the elastic nature of the fabric, the pack is comfortable to wear, as it flexes to move with the movements of the runner. However, the elastic nature of the fabric can allow fluid to pool in the bottom of the bladder as a result of gravity. To counteract this while still maintaining comfort, placement of the zipper in a horizontal orientation across the lower portion of the pack restrains the fluid in this region. The mechanism for this is apparent: given that the zipper is inelastic, it prevents stretching of the pack material and distension of the bladder at this region. As a result, a portion of the fluid within the bladder is forced upwards, resulting in a more even vertical distribution of fluid within the bladder. In testing, it was found that the ideal distance of the zipper from the bottom of the pack, shown by the arrow z, was approximately one fourth the length of the vertical axis, shown here by the arrow V. However, depending on the shape of the bladder, ratios of z/V of between 0.15 and 0.5 were found to be suitable.
The fluid-filled bladder behaves very similarly to adipose tissue, and if a sports bra is used as a model for comparison, the design can be thought of as an approximation of the adipose tissue of breasts, which are restrained in a similar fashion by elastic fabric that produces a compression of the adipose tissue against the user's body. For this reason, the present design is adipo-mimetic in that the flexible fluid-filled bladder mimics the behavior of adipose tissue. Although most of the support and immobilization comes from the elastic tensioned fabric of the pack, the zipper, by functioning similarly to an under wire in a sports bra, provides an additional level of support due to its inelastic properties.
Placement of the waist straps 42 and 46 at angles relative to the horizontal axis of the pack H produces further stability. In testing it was found that placement of the straps parallel to the horizontal axis resulted in unequal distribution of tension across the pack, with the result being that the upper portion of the pack would tend to fall away from the user's back, producing an unpleasant flopping action. By placing the straps at an angle θ above the horizontal axis, greater tension is produced across the upper portion of the pack, which is then tensioned firmly against the user's back. Testing of prototypes found that an angle θ of between 15° and 60° produced the most efficient mobilization of the pack. An additional element of construction involves a row of stitching 26 through front and back layers of the pack, thus defining a compartment within which the bladder is constrained, and preventing lateral movement of the bladder within the pack. The tapered portions of the pack lateral to the stitching 26 act as transition zones between the large bladder-containing portion of the pack and the more narrow waist straps 42 and 46. These transition zones act to distribute the tension generated by the waist straps 42 and 46 more uniformly across the bladder.
An alternate embodiment to the angled strap arrangement is shown in
Although the above description contains many specifics, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the preferred embodiments of this invention. For example, although the zipper placement is chosen for its motion-damping qualities, it would be possible, although more complicated, to place the zipper elsewhere on the pack, and sew an additional inelastic ribbon, cord, or adjustable strap in the lower portion of the pack. Similarly, placement of the straps at an angle above horizontal produces an increase in tension across the top of the pack, preventing it from flopping away from the user's body. In addition to the adjustable straps shown in
Conclusion, Ramifications, and Scope of Invention
Accordingly, the reader will see that the hydration system for runners described herein represents a significant improvement over previous designs, and solves a long-felt need for runners, particularly those who reside in hot climates. The flexible bladder can be filled with several liters of cold liquid and ice to ensure that the fluid will remain cold during long hot runs. The flexible, elastic, and thermally-insulating fabric pack attaches securely about the waist, provides superior motion control without restricting movement of the runner's musculature or other soft tissue, and is unobtrusive due to its low profile. The pack is pre-stressed and self-adjusting to provide tension as the bladder volume changes.