Patent Publication Number: US-6666360-B1

Title: Personal hydration system for runners

Description:
FEDERALLY SPONSORED RESEARCH 
     Not Applicable 
     SEQUENCE LISTING OR PROGRAM 
     Not Applicable 
     BACKGROUND 
     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 urinary 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&#39;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 two essential design criteria. One is that the device must utilize a stable, non-irritating waist-mounted system with sufficient motion control to minimize bounce and sway. Another is that the device must provide a simple, lightweight, and inexpensive means for delivering fluid from waist level to mouth level. 
     One type of hydration system for runners utilizes one or more water bottles attached to a waist-mounted belt. U.S. Pat. Nos. 6,241,135 and D444,295 describe similar waist-mounted bottle/flask systems. One problem with this type of system is that the bottles are rigid, and the center of mass of the attached water bottles is relatively far from the center of mass of the runner. Furthermore, as the bottles are drained with use, water is free to slosh about. Consequently, it is difficult to provide motion control for these bottles, and the bouncing of the rigid bottles against the user is uncomfortable. 
     Personal hydration systems used by cyclists employ a flexible bladder encased in a fabric pack and mounted upon the cyclist&#39;s back with shoulder straps. Fluid is delivered by a tube with a bite-valve that delivers fluid when the user bites down on the end; one embodiment of this type of hydration system is disclosed in U.S. Pat. No. 5,060,833. Because of the bent-over posture of a cyclist, the elevated position of the pack relative to the user&#39;s mouth creates a hydrostatic head that allows for gravity-driven flow of fluid from the pack to the user&#39;s mouth. Although this type of hydration system has seen widespread use among cyclists, runners have not embraced this type of system for two important reasons: lack of motion control and difficulty in drawing water from back level to the mouth level due to the upright posture of the runner. Although such a device, when mounted on the back, is suitable for a cyclist whose body remains relatively stable in both the horizontal and vertical planes, the lack of motion control makes it unsuitable for a runner, whose torso tends to oscillate, creating unacceptably large oscillations of the pack in the vertical (bounce) and horizontal (sway) directions. This motion of the pack can chafe the user, and fatigue the upper back, neck, and shoulder muscles. There is little that can be done to increase the amount of motion control of a back-mounted pack, as increased strap tension produces unacceptable stress on the user&#39;s neck, back, and shoulder muscles. Furthermore, because of the upright posture of the runner, the pack is located below the user&#39;s mouth, and the loss of a hydrostatic head results in a need to draw water by suction, a difficult task when running. 
     Manufacturers of back-mounted hydration packs have attempted to adapt these devices for runners so that they may be worn about the waist or hips. These waist-mounted packs are essentially back-mounted designs retro-fitted with a waistband, designed without consideration of the unique needs of runners. Because of the lower center of gravity relative to back-mounted packs, placement of a hydration pack at waist level is desirable. However, this placement makes it difficult to draw the fluid to mouth level, as it requires an unacceptably high amount of suction from the user to draw the liquid from waist level to mouth level. One possible solution to this problem is to include a pump to force the liquid to mouth level; U.S. Pat. Nos. 5,645,404 and 5,571,260 describe similar devices. However, the inclusion of a pump and its obligatory power supply results in disadvantages of both increased weight and cost. Another approach is to pressurize the bladder; U.S. Pat. No. 6,409,048 utilizes compression plates on opposing sides of the bladder, and compression is achieved by a number of straps which must all be cinched up in order to squeeze the two plates together. However, this design presents several problems. As fluid is drained, the straps must be continually tightened to maintain pressure, a cumbersome task. The plates must also be stiff, turning the bladder into an uncomfortable rigid body. 
     Because a cyclist has little body motion relative 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&#39;s back, the pack can be constructed of non-elastic 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 too does the pressure on the user&#39;s muscles, tendons, and other tissue. Thus, 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. Non-elastic fabric does not allow for this, and may represent a potential source of repetitive stress injury to runners who use such systems. 
     Another problem that arises with the use of non-elastic cloth relates to the ability of the fabric to prevent motion of the bladder within the fabric pack. The basic design of prior art packs is a bladder within a fabric bag. Because the fabric is non-elastic, the maximum tension against the bladder is achieved only when the bladder is completely filled. 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 additional motion of the entire system. Numerous systems utilize additional straps to take up the slack created by decreasing bladder volume, however, these must be continually tightened, a cumbersome task. 
     One means by which to achieve motion control is to make the attached object an integral part of the runner&#39;s body such that the amplitude of motion is reduced and more in phase with the runner. A consideration of the problems faced by women runners may be informative. Breast tissue has fluid properties, and running produces considerable motion of the tissue. The solution to this problem is provided by athletic bras designed to restrain the breast by compression against the body, an effect accomplished through the means of snug-fitting elastic fabric as shown in U.S. Pat. No. 4,174,717. This compression decreases the moment of inertia of the tissue by reducing the distance of the center of mass of the tissue to the center of mass of the subject. The elastic fabric also dampens tissue motion. The physical properties of a flexible fluid-filled bladder suggest that a similar design would work in a waist-mounted hydration system. 
     Delivery of fluid from waist-level to the mouth presents additional obstacles. It is not possible to use a tube delivery device while running, as this requires prohibitively large suction forces that are impossible to generate while breathing at a high rate. However, unlike cyclists, runners are free to use their hands, and it is common practice during races to provide water in disposable cups. Cups are problematic, though, as it is easy both to spill their contents and to accidentally choke when running. Squeeze bottles present less risk of spillage and choking, but are rigid, bulky, and uncomfortable due to excessive motion. Smaller bottles bounce around less, but at the cost of reduced capacity. Some designs utilize multiple small squeeze bottles to increase total fluid capacity. However, these devices are bulky and uncomfortable, and it is awkward to clean and fill multiple bottles. Furthermore, infiltration of air to displace dispensed fluid produces sloshing regardless of the size of the bottle. 
     Prior art hydration systems suffer from a number of additional problems. Because of 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. U.S. Pat. No. 5,427,290 discloses a back-mounted system that attempts to remedy this with a baffle in the lower portion of a flexible bladder. The resultant bladder is difficult to clean and dry, however, as a large portion of the inner and outer face of the bladder remains in permanent apposition. This presents a potential health hazard, as residual fluid in the bladder can support the growth of mold and other harmful microorganisms. 
     Given that hydration systems are most useful in hot weather, thermal insulation is essential to prevent fluid warming. However, all prior art packs employ a design in which additional thermal insulation is sewn into the fabric pack, and this increases the complexity and cost of construction. Ideally, the fabric would not only have the desired mechanical properties, but would also provide thermal insulation without the need for additional fabric layers. 
     OBJECTS AND ADVANTAGES 
     It can be seen that prior-art hydration systems for runners suffer from a number of problems, including: 
     a) insufficient motion control resulting from inefficient immobilization and attachment of the bladder and pack; 
     b) insufficient motion control resulting from air infiltration into bottles, resulting in sloshing; 
     c) discomfort due to inelastic fabric; 
     d) inability to deliver fluid to the user&#39;s mouth in an efficient manner; 
     e) inefficient incorporation of thermal insulation. 
     Accordingly, several objects and advantages of the present invention include: 
     a) to provide a means for attaching a flexible fluid-filled bladder to the waist such that motion of the bladder is dampened and minimized by compression against the runner&#39;s body; 
     b) to prevent pooling of liquid in the lower portion of the bladder while maintaining ease of cleaning and air drying of the bladder; 
     c) to provide a means for attaching the flexible fluid-filled bladder to the waist such that the pack is comfortable and does not irritate sensitive underlying tissue; 
     d) to provide efficient incorporation of thermal insulation to the hydration system; 
     e) to provide a means for delivery of fluid from the fluid-filled bladder to the mouth of the user via a small squeeze bottle that is securely attached to the waist, fits easily in the hand, and can be removed from the waist and raised to the mouth of the user for dispensing; 
     f) to provide a means for automatic filling of the squeeze bottle from the flexible bladder attached to the waist; 
     g) to provide a means for the prevention of air infiltration into the system to prevent sloshing. 
     Other objects and advantages will become apparent from a consideration of the following description and drawings. 
     SUMMARY 
     The following invention is a personal hydration system designed for runners and joggers, and consists of a flexible bladder that contains 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 constrained by compression against the user&#39;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&#39;s body is maintained at all times, providing constant motion control. A semi-rigid plastic compression plate fits between the bladder and the outer fabric layer of the pack, providing uniform distribution of force against the bladder. Snaps pinch the lower portion of the bladder together at a point, and prevent fluid from pooling in the lower half of the flexible bladder. Fluid is delivered to the mouth of the user by means of a small squeeze bottle mounted on the waist and connected to the main reservoir by a tube that provides automatic filling of the squeeze bottle. One-way check valves bias fluid flow from the main bladder to the squeeze bottle and to the user&#39;s mouth, thus preventing air infiltration into either the satellite bottle or main bladder, a feature that eliminates sloshing. The bottle is easily removed to deliver fluid to the mouth of the user, and is easily attached to the waist when not in use. Because the squeeze bottle has a small mass and is attached firmly to the user&#39;s waist when not in use, it does not produce any appreciable motion when running. 
    
    
     DRAWINGS 
     Drawing Figures 
     FIG. 1 is a perspective view of the present invention in use by a runner. 
     FIG. 2 is a perspective view of the invention. 
     FIG. 3 is a front elevation view with the front fabric removed to reveal the inner components of the pack. 
     FIG. 4 is a fragmentary perspective view of the attachment of the squeeze bottle to the quick-connect socket. 
     FIGS. 5A,  5 B, and  5 C are fragmentary side elevation views showing how the squeeze bottle is mounted and removed from the socket support panel. 
     FIGS. 6A and 6B are schematic representations of dispensing from and filling the squeeze bottle shown in FIGS. 1,  2 , and  3 . 
     FIGS. 7A,  7 B, and  7 C are schematic representations of dispensing from and filling of the squeeze bottle shown in FIGS. 4,  5 A,  5 B, and  5 C. 
     FIGS. 8A and 8B show front elevation and rear elevation views of the bladder respectively. 
     FIGS. 9A and 9B are cross-sectional views taken about line  9  of FIG.  8 A and show the effect of engaging the snap fastener elements on the distribution of fluid in the bladder. 
     FIG. 10A is a fragmentary perspective view of a prior art hydration pack. 
     FIG. 10B is a fragmentary perspective view of the hydration pack. 
     FIG. 11A is a cross-sectional view about the line  11  of FIG. 10A showing the loading of the pack with a full bladder. 
     FIG. 11B is a cross-sectional view about the line  11  of FIG. 10A showing the loading of the pack with a partially empty bladder. 
     FIG. 12A is a cross-sectional view about the line  12  of FIG. 10B showing the pack before insertion of bladder. 
     FIG. 12B is a cross-sectional view about the line  12  of FIG. 10B showing the loading of pack with a full bladder. 
     FIG. 12C is a cross-sectional view about the line  12  of FIG. 10B showing the loading of the pack with a partially empty bladder. 
     FIG. 13 is a cross-sectional view about the line  13  of FIG. 10B showing the effects of the snap elements and the compression plate on the distribution of fluid within the bladder. 
    
    
     REFERENCE NUMERALS IN DRAWINGS 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 10 
                 Squeeze bottle assembly 
               
               
                   
                 11 
                 Bladder cap 
               
               
                   
                 12 
                 Bladder opening 
               
               
                   
                 13 
                 Cap orifice for tube insertion 
               
               
                   
                 20 
                 Hydration pack 
               
               
                   
                 21 
                 Outer fabric layer 
               
               
                   
                 21a 
                 Outer fabric layer - prior art 
               
               
                   
                 22 
                 Inner fabric layer 
               
               
                   
                 25 
                 Zipper 
               
               
                   
                 27 
                 Outlet hose 
               
               
                   
                 31 
                 Badge reel 
               
               
                   
                 32 
                 Badge reel cord 
               
               
                   
                 33 
                 Badge reel clip 
               
               
                   
                 41 
                 Right side elastic fabric waistband 
               
               
                   
                 41a 
                 Right side fabric waistband - prior art 
               
               
                   
                 42 
                 Right side buckle strap 
               
               
                   
                 43 
                 Hook fastener 
               
               
                   
                 44 
                 Right buckle element 
               
               
                   
                 45 
                 Left buckle element 
               
               
                   
                 46 
                 Left side buckle strap 
               
               
                   
                 47 
                 Left side elastic fabric waistband 
               
               
                   
                 47a 
                 Left side fabric waistband - prior art 
               
               
                   
                 48 
                 Fingers of user&#39;s hand 
               
               
                   
                 51 
                 Quick-connect socket 
               
               
                   
                 53 
                 Socket support panel 
               
               
                   
                 55 
                 Quick-connect insert 
               
               
                   
                 61 
                 Bottle inlet check valve 
               
               
                   
                 63 
                 Squeeze bottle body 
               
               
                   
                 64 
                 Insulated cover for bottle 
               
               
                   
                 65 
                 Loop fastener 
               
               
                   
                 70 
                 Squeeze bottle cap 
               
               
                   
                 71 
                 Bottle outlet check valve 
               
               
                   
                 80 
                 Runner 
               
               
                   
                 90 
                 Bladder 
               
               
                   
                 90a 
                 Bladder - prior art 
               
               
                   
                 91 
                 Bladder - front face 
               
               
                   
                 92 
                 Front snap element 
               
               
                   
                 93 
                 Bladder - rear face 
               
               
                   
                 94 
                 Rear snap element 
               
               
                   
                 95 
                 Compression plate 
               
               
                   
                   
               
            
           
         
       
     
     DETAILED DESCRIPTION 
     FIG. 1 broadly discloses a runner  80  using the present invention, which consists of a pack  20  mounted about the waist and which holds a bladder  90  filled through a cap  11  and which contains fluid for drinking. The fluid is delivered to a small removable squeeze bottle assembly  10  by means of a hose or tube  27 . The squeeze bottle  10  is mounted on the waist when not in use and raised to the mouth for dispensing as shown. In the present embodiment the hose  27  is continuous from the cap  11  to the squeeze bottle  10  and is restrained by a badge reel  31  attached to an elastic fabric waist band  41 ; the badge reel  31  contains a retractable cord  32  which attaches to the tube  27  by a small clip  33 . 
     FIG. 2 is a more detailed view of the invention. The bladder  90  is contained within the pack  20  which is composed of two layers of fabric, with an outer layer  21  being shown here. The bladder  90  is removed from and inserted in the pack  20  via a zipper  25 . The bladder  90  is filled via an opening  12  and sealed by means of the cap  11  which can be either threaded or snap-on. The tube  27  inserts into the cap  11 , and the lumen of the tube  27  is contiguous with the fluid-filled interior of the bladder  90 . The bottle assembly  10  broadly describes a plastic squeeze bottle  63  encased in an insulating fabric  64  with a cap  70  and an outlet check valve or spout  71 . The tube  27  attaches to the bottle assembly  10  via an inlet check valve  61  with integral fitting. The check valve  61  is secured into the bottom of the squeeze bottle  63 . Fluid is dispensed from the bottle  63  via the outlet check valve or spout  71 . The bottle  63  is enrobed in the insulating fabric  64 , which in the preferred embodiment is neoprene fabric. The insulating fabric layer  64  has attached to it a Velcro™ loop fastener  65  which allows attachment of the bottle assembly  10  to a Velcro™ hook fastener  43  attached to the right side fabric waistband  41 . The badge reel  31  attached to the fabric waistband  41  contains the retractable cord  32  which attaches to the tube  27  via the small clip  33 . The pack  20  is mounted about the waist by means of a left side fabric waistband  47  which is attached to the left side of the pack  20  on one end and attaches on the other end to a left side buckle strap  46  which is attached to a left buckle element  45 . The right side elastic fabric waist band  41  which is attached to the right side of the pack  20  on one end attaches on the other end to a right side buckle strap  42  which attaches to a right side buckle element  44 . The left buckle  45  and the right buckle  44  snap together to constrain the pack  20  about the waist of the user  80 . 
     FIG. 3 shows the pack  20  with the front fabric  21  removed. An inner fabric layer  22  is joined to the front fabric  21  by a seam about the periphery and apposes the back of the user  80 . The inner and outer fabric layers are ideally made from neoprene fabric, which provides the desired mechanical properties as well as thermal insulation to prevent the fluid from warming. The bladder  90  is composed of a front face  91  seen here and in FIG. 8B and a rear face  93  seen in FIG. 8B; the front and rear face are composed of flexible water-impermeant sheeting or membrane joined at the perimeter to define an inner compartment to hold fluid. The bladder  90  is filled via the opening  12  and sealed with the cap  11 . The tube  27  inserts into the cap  11  at one end and attaches to the bottle  10  at the opposite end via the check valve  61 . The tube  27  is of sufficient length to allow the squeeze bottle  10  to be raised to mouth level, and is restrained when not in use by the badge reel  31  attached to the right side elastic waist band  41 . The badge reel  31  contains the retractable cord  32  that attaches to the tube  27  via the clip  33 . The bottle  10  is composed of the squeeze bottle  63  which in this view is obscured by the insulating fabric  64 , and is attached to the pack  20  via the bottle-attached loop fastener  65  and the waist-mounted hook fastener  43 . The top of the squeeze bottle  63  is covered with the cap  70  to allow cleaning and drying when not in use. Fluid is dispensed from the bottle  10  via the outlet check valve  71  that allows flow of fluid only from the bottle, thus preventing infiltration of air back into the bottle. The front fabric layer  21  and rear fabric layer  22  of pack  20  are attached on each side to the left fabric waistband  47  and the right fabric waistband  41  which are attached respectively to the buckle straps  46  and  42  which attach respectively to the left buckle  45  and the right buckle  44  elements which are then connected or coupled in the front of the user  80 . Because of the elastic nature of the outer fabric layer  21  and inner fabric layer  22 , when the pack  20  is mounted about the waist, tension is generated in the inner fabric layer  22  and the outer fabric layer  21 , exerting a compressive force upon the front bladder face  91 . A flat plastic panel or compression plate  95  acts to distribute the pressure of the outer fabric layer  21  against the front bladder face  91 . 
     FIG. 4 demonstrates an alternate embodiment of the invention. As with the previous descriptions, the bottle assembly  10  comprises the squeeze bottle  63 , which is covered by the insulating fabric  64 . Fluid is dispensed via the check valve nozzle or spout  71  attached to the cap  70 , and the bottle is filled via the tube  27 . The tube  27  attaches to a quick-connect fluid coupling socket element  51  which is mounted on a plastic socket support panel  53  that attaches by stitching, adhesive, or riveting to the right buckle strap  42 . The bottle  10  attaches to the socket support panel  53  via the bottle-attached loop fastener  65  which attaches to the hook fastener  43  attached by adhesive or stitching to the socket support panel  53 . A quick-connect fluid coupling insert  55  is attached to the bottle  63 . The quick-connect insert  55  inserts into the quick-connect socket element  51  for filling of the bottle. Check valves in the insert  55  and the socket  51  prevent fluid flow when the two elements are disconnected. When insert  55  is inserted into socket  51 , the check valves are opened and fluid is free to flow from the bladder  90  to the bottle  63  via the tube  27 . 
     FIG. 5A shows the bottle  10  removed from the socket support panel  53  attached to the right elastic fabric waistband  41 ; stitching, adhesive, rivets are all possible means for attachment to the waistband. The quick-connect insert  55  is visible, and the dashed line shows how the insert  55  is inserted into the quick-connect socket  51  attached to the socket support panel  53 . FIG. 5B shows the bottle  10  after the quick-connect insert  55  has been inserted into the quick-connect socket  51 . The configuration of the socket  51  and socket support panel  53  are such that the loop fastener  65  and the hook fastener  43  do not engage during insertion or removal of the bottle  10 , thus allowing unimpeded insertion and disengagement of the quick-connect insert  55  with the quick-connect socket  51 . The socket support panel  53  is constructed of semi-pliable plastic such that after insertion of insert  55  into socket  51 , the bottle  10  can be pressed against the socket support panel  53  such that the hook fastener  43  engages the loop fastener  65 , seen in FIG. 5C, thus preventing disengagement of the fluid coupling consisting of quick-connect insert  55  and quick-connect insert  51 . 
     FIGS. 6A and 6B show how the bottle  10  shown in FIGS. 1,  2 , and  3  dispenses fluid and is filled. When the bottle  63  is squeezed by the fingers of a hand  48 , fluid exits the bottle  63  via a dispensing nozzle or spout with check-valve  71  biased to allow fluid to flow only out of the bottle in the direction of the arrow. This biasing of fluid flow prevents air from infiltrating the bottle when the user releases the bottle. The bottle  63  also contains at the bottom the check valve  61  to which the tube  27  is attached and from which water flows from the bladder  90  when the bottle is released from the grip of the fingers  48  of the user. The valve is biased to allow fluid to flow only into the squeeze bottle  10  in the direction of the arrow seen in FIG. 6B; this biasing prevents backflow of fluid from the bottle  63  into the bladder  90 . 
     FIGS. 7A,  7 B, and  7 C show the configuration of the bottle  10  shown in FIGS. 4,  5 A,  5 B, and  5 C. When squeezed by the fingers  48 , fluid exits via the dispensing nozzle or spout with check valve  71 , which is biased to prevent air from infiltrating the bottle  63 . The quick-connect insert  55  has an integral check valve, which remains closed unless engaged with the quick-connect socket  51 . When released from the user&#39;s grip as seen in FIG. 7B, no air is allowed to infiltrate the bottle  63 , due to the action of the check valve spout  71  and the quick-connect insert  55  which allows flow only when engaged with the quick-connect socket  51 . When the quick-connect insert  55  is inserted into quick-connect socket  51 , the fluid coupling is completed, the check valves of the quick-connect insert  55  and quick-connect socket  51  are disengaged, and fluid is free to flow into the bottle  63 . 
     FIGS. 8A and 8B show the front and rear views respectively of the bladder  90 , which is composed of two apposed sheets of flexible water-impermeant plastic material. Food- or beverage-grade polyvinylchloride, polyolefin, polyurethane and polyethylene are some of the many suitable plastics available for construction, but others that are approved for food and beverage use, are sufficiently pliable, water-impermeant, and readily seamed may also be suitable. The front sheet  91  is attached to a rear sheet  93  by seaming about the outer edges; the method of seaming may be adhesive, thermal, radio frequency, or ultrasonic depending on the requirements of the sheeting. The cap  11  is attached to the opening  12  on the front sheet  91 . The cap  11  contains a small hole or orifice  13  into which the tube  27  is inserted, thus providing means for exit of fluid from the bladder  90 . Attached to the front sheet  91  is a snap element  92 , which engages a complementary rear snap element  94 , which attaches to the rear bladder sheet  93 . The snap elements  92  and  94 , when engaged, position a small portion of the front bladder sheet  91  in apposition with a small portion of the rear bladder sheet  94 . Because of gravity, fluid will tend to pool at the bottom of bladder  90 ; snapping the bladder  90  together at this point pinches the bladder to allow uniform distribution of the fluid. Because the snaps  92  and  94  can be unsnapped, cleaning and air-drying of the interior of the bladder  90  is easier than if the bladder  90  were permanently welded together at the location where the snaps  92  and  94  are located. 
     FIGS. 9A and 9B are cross-sectional views taken through the line  9  in FIG.  8 A and show more clearly the effect of the snap elements  92  and  94  on fluid distribution in the bladder  90 . FIG. 9A shows the bladder  90  fully filled with fluid and without engagement of the snaps  92  and  94 . Because of gravity, fluid pools in the bottom of the bladder  90 , resulting in an uneven distribution of fluid and an increase of distance of the center of mass of the bladder  90  to the user who is in apposition to the rear face  93 . FIG. 9B shows the effect of engaging the snap elements  92  and  94 , with the result that the lower portion of the bladder  90  is pinched, thus forcing fluid higher up into the bladder  90 . The snap elements  92  and  94  have an additional function, which is to dampen the movement of fluid within the bladder  90 , and this dampening helps to reduce overall motion of the bladder  90 . 
     FIG. 10A shows a prior art hydration pack  20   a  with an outer fabric layer  21   a  which attaches to a left fabric waistband  47   a  and a right fabric waistband  41   a  which constrains the pack  20   a  about the user&#39;s waist. FIGS. 11A and 11B are cross-sections through the line  11  in FIG.  10 A. The outer fabric layer  21   a  is joined to an inner fabric layer  22   a , which apposes the user&#39;s, waist. The fabric layers  21   a  and  22   a  define the compartment or pack  20   a  into which a bladder  90   a  is inserted. Because the fabric layers  21   a  and  22   a  are typically constructed of non-elastic fabrics such as nylon or polyester pack cloth, the volume of the interior of the pack defined as the region between layers  21   a  and  23   a  is constant. The volume of the bladder  90   a  is variable, however, as a function of the volume of fluid contained therein. Although the bladder  90   a  when full presents a snug fit in FIG. 11A, when the bladder  90   a  is partially drained during use as in FIG. 11B, the volume of the bladder  90   a  is reduced while the volume of the pack  20   a  remains constant, and thus the bladder  90   a  is free to bounce around within the pack  20   a.    
     FIG. 10B shows the present invention. The outer fabric layer  21  attaches to a left fabric waistband  47  and a right fabric waistband  41  which constrain the pack  20  about the user&#39;s waist. FIGS. 12A,  12 B, and  12 C are cross sections taken through the line  12  in FIG.  10 B. FIG. 12A shows the pack  20  without the bladder  90  and without the compression plate  95 . The outer fabric layer  21  is attached to the inner fabric layer  22  and is constrained about the user&#39;s waist by the attached left fabric waistband  47  and right fabric waistband  41 . The volume of the interior of the pack  20  is defined by the region enclosed by outer fabric layer  21  and the inner fabric layer  22 . Here it can be seen that without the bladder, the volume of the unloaded pack is zero. Therefore, given that the bladder  90  has a volume equal to the fluid volume contained therein, insertion of the bladder  90  into the pack  20  produces an increase in volume of the interior of the pack  20  and this must be accomplished through the act of stretching the inner fabric layer  22  and the outer fabric layer  21 . Given that the back of the user approximates a flat planar surface, the outer fabric layer  21  will undergo a larger amount of stretch than the inner fabric layer  22 . As seen in FIG. 12B, when the full bladder  90  is inserted into the pack  20 , the outer fabric layer  21  stretches a greater amount than the inner fabric layer  22 , and thus, relative to the inner fabric layer  22 , there is greater tension in the outer fabric layer  21 , thus producing a force against the bladder  90  such that the bladder  90  is maintained in compression against the user&#39;s back. Unlike the prior art pack shown in FIG. 10A, the volume of the pack  20  of the present invention changes as a function of the volume of the bladder  90  contained within the pack  20 . Furthermore, unlike the prior art pack  20   a  shown in FIGS. 10A,  11 A, and  11 B, the pack  20  is pre-stressed upon loading of the bladder  90 . 
     The tension in the outer fabric layer  21  is self-adjusting, because this tension is proportional to the amount of stretch in the outer fabric layer  21 , and this is a function of the volume of the bladder  90 . When the bladder  90  is fully loaded, the necessary tension to restrain it is greater, and because of the increased stretch of the outer fabric layer  21 , tension is increased. When the bladder  90  is empty, as it may be towards the end of a run, the tension needed to restrain the bladder  90  is minimal; because of the decreased stretch of the outer fabric layer  21 , tension is likewise decreased. 
     FIG. 13 is a cross-section through the lines  13  in FIG.  10 B. As seen in FIG. 9A, when the snaps  92  and  94  are not engaged, fluid pools in the lower portion of the bladder  90 . In FIG. 9B, engaging of the front snap  92  with the rear snap  94  acts to pinch the lower portion of the bladder  90  such that fluid is forced upwards. However, because of gravity, fluid will still tend to pool in the lower portion of the bladder  90 . To produce a uniform distribution of fluid in the vertical direction, greater pressure must be exerted on the lower portion of the bladder  90  where the fluid pools. As seen in FIG. 13, the compression plate  95  acts to distribute the force of the tensioned outer fabric layer  21  more uniformly across the bladder  90 ; this, along with the constriction provided by the snap elements  92  and  94 , ensures that the fluid does not pool in the lower region but is instead distributed more evenly from top to bottom. Furthermore, the constriction of the snaps  92  and  94  and the action of the compression plate  90  both serve to dampen motion of the pliable bladder  90 , resulting in increased motion control. Although semi-rigid, because the compression plate  90  is against the outer face of the bladder, the user only feels the soft pliable bladder and not the rigid plate, a feature which increases comfort. 
     DESCRIPTION AND OPERATION OF ALTERNATIVE EMBODIMENTS 
     Although the above description contains many specificities, 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 tube  27  is shown inserted into the cap  11 , it could also be directly inserted into the bladder  90 , either directly, or via an adapter or other configuration that provides for the lumen of the tube to be contiguous with the interior of the bladder. Furthermore, direct insertion of the tube into the bladder would allow other embodiments for filling the bladder; for example, the cap could be replaced with a zip-top closure or a roll-down closure. The tube could also be wrapped in an insulating outer layer to lessen warming of the fluid in the tube during hot weather. The bladder  90  is shown as ovoid, however, it may be constructed in a variety of shapes, such as circular, or rectangular, or elliptical, with the long axis oriented either in the horizontal or vertical directions. 
     The bottle  10  could be attached to either the left or the right side, depending on the preference of the user. The bottle shown here has an elliptical cross-section, but other shapes might be desirable. For example, the face that apposes the waist could be flattened so that the cross-section approximates a semi-circle; this might provide greater contact between hook and loop fastener elements. In addition to the bottle  10  used to provide hydration from the main bladder  90 , it might also be desirable to include an additional bottle that is not attached to the main bladder. This bottle could be mounted with hook and loop elements on the side opposite the bottle  10 , and could be filled with carbohydrate solution. Furthermore, although hook and loop fastener is the preferred means of attachment, the bottle  10  could also be constrained by means of a small pocket of fabric that would function as a holster. Other embodiments might include a clip or a snap element on the waistband and bottle  10  such that the bottle would clip or snap firmly onto the waist. 
     The pack  20  as shown attaches to elastic fabric waistbands, which then attach to straps connecting to the buckle elements. It would be possible to eliminate the waistbands, straps, or both, such that the pack fabric attaches either directly to the straps or directly to the buckles. This would result in greatly simplified construction, offsetting the increased waste of fabric that would result from cutting out such a large and irregular piece of fabric. Buckles could also be replaced by hook and loop fastener, or fasteners could be eliminated and the entire pack could be constructed such that it comes in a variety of sizes and could be slipped on as a single unit much like a sport bra or undergarment. 
     The outlet check valve  71  may be chosen from the group of check valves that includes the following: ball, flap, disk, diaphragm, or reed. The specific type is not shown here because the functional results are similar. Likewise, there are many different acceptable types of commercially available quick-connect couplings composed of the socket  51  and insert  55  described herein. For example, although the coupling shown herein relies on a simple linear insertion of the insert  55  into the socket  55 , other quick-connect couplings utilize insertion followed by a quarter-turn twist to secure the coupling. 
     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 up to several liters of cold liquid along with large quantities of ice to ensure that the fluid contained within will remain cold through 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&#39;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. Delivery of ice-cold liquid is a simple one-handed operation, as the user simply removes the small squeeze bottle from the waist-band, raises it to the mouth, and squeezes. The squeeze bottle fills automatically, and thus the user does not have to perform any other actions besides dispensing.