fig1 shows the cuff generally at 10 , which is constructed of flotation material or cells 14 , such as closed cell foam , which is surrounded by an elastic , durable material 16 , such as neoprene , which can be buoyant . the edges 18 of the flotation cells 14 have stitching 20 to hold the flotation cells in place within the elastic material covering 16 . the edges are those of the material which surrounds the flotation cells . each cell 14 has material 16 surrounding it , after which these are sewn to each other . at each end of the cuff 10 is a strong ridged ring 22 made of extremely durable , yet flexible , and somewhat pliable material . this material may be a high impact plastic . ring 22 , located at each end of the cuff 10 provides added integrity to the overall structure of the device . an o - ring 24 is attached to the cuff 10 using a strong flexible strap 26 . these o - rings act as attachment sites for the elastic cords . the flexible strap can be made of latex tubing , for example . the flexible strap 26 allows the o - ring 24 to change its position when the elastic - resistive cord 28 ( not shown in this figure ) places tension upon it . fig2 shows a modified embodiment from that shown in fig1 but has two additional components . there is a strong velcro strap 30 ( or zipper ) used when the cuff is designed with a separation 32 , rather than being continuous as in fig1 to allow easy donning and doffing . this is used if a person has a sprained ankle and would not be able to stretch the cuff 10 over the user &# 39 ; s ankle , for example , without possibly damaging the injured joint further . a user inserts and removes the limbs through the central opening which runs the entire length of the device . fig3 shows the mitt generally at 12 made of flexible , durable , non - buoyant or buoyant material 34 . this material may be closed cell foam covered by neoprene which will allow the mitts to be buoyant . in the preferred embodiment , the mitt 12 is shaped similarly to a person &# 39 ; s hand , with stitching 36 that follows the outline of the hand and fingers . there is a web space 38 formed between the fingers and thumb which allow for entrapment of water during movement through the water medium for increased resistance during exercise . there is also located on the mitt 12 an o - ring 40 which is attached to the adjustable wrist band 42 via a durable and flexible strap 44 . for enhanced fit of the wrist band 42 there is a buckle 46 which allows for passage of the wrist band 42 which is made of a strong flexible material with velcro for closure . an example of an upper extremity exercise is one where the exerciser orients , for example , the soft buoyant surface of the preferred embodiment facing , at any angle , to the frontal plane of progression ( see fig7 for clarification ) through the water medium . the cuff 10 is worn over the wrist or forearm . resistance increases the more one orients the surface of the preferred embodiment toward 90 degrees to the direction of movement within the water medium , with theoretically maximal resistance attained at 90 degrees . the user can select how much resistance the cuffs 10 and mitts 12 can produce based upon : 1 . the speed at which the cuffs 10 or mitts 12 are moved through the water ; 2 . at what percentage of total submersion the preferred embodiments are held ; 3 . what particular angle to the direction of movement the cuffs 10 and mitts 12 are positioned ; and 4 . the density of the material or materials of the preferred embodiments determines the buoyancy or relative density , and thus if the buoyancy is to be changed , one way to accomplish this is to change the materials used . this is determined in advance by comparing the density of the object to that of the water in which the device is to be used . the cuffs 10 can additionally be used for many lower extremity exercises . an example is using the cuffs 10 over the ankles 48 for water running or when the user performs seated bilateral or alternating knee flexion and extension as shown in fig5 . this exercise enhances strength , coordination , flexibility , and balance which may be utilized in fitness training and rehabilitation . the cuffs 10 and mitts 12 can be used as flotation aids for therapists , trainers , and aquatic specialists . an example of this particular usage is when a patient / client lies supine or prone , or in an upright position , depending upon the particular requirements of an exercise or series of exercises . for example , if a patient has a neck or back strain the supine or upright positions will probably be desired . injuries other than those which involve the spine can usually tolerate prone , supine , and upright positions . in this case , one may use a pair or two pairs of cuffs which can be placed for usage on two or all four extremities ( keeping in mind that the mitts are only used on the hands and wrists ). the invention provides balance , or proprioceptive training . the human body contains multiple proprioceptive sensory organs ( mpso ) which inform the central nervous system of the position or orientation in space where each joint is located relative to one another , and provides various other qualitative and quantitative elements specific to each joint such as : velocity ; degree of rotation ; compression ; torque ; elasticity of the tissue in close proximity to the joint ; and the perceived integrity or stability of each joint . these mpso are truly the limiting factor to one &# 39 ; s stability during any static or dynamic task or series of tasks / movements . without correct functional operation of the mpso one literally loses the ability to perform any movement with safety , control , or grace / fluidity . the present invention , when used as a balance training device , brings into usage three innate neurological human neurophysiological responses : righting reactions involve orienting movement of the head , neck , and body to maintain the eyes horizontal , head vertical , and the body in proper relationship to the head . stimulus may be optical , labyrinthine , or tactile of which the water is a perfect dynamic medium for these stimuli to occur due to its innate physical characteristics . secondly , balance reactions are movements that attempt to maintain the center of gravity or buoyancy ( cog or cob ) within the base of support ( bos ), which is defined as the outermost limits or edges of the person &# 39 ; s balance range . equilibrium reactions are mediated through the more peripheral proprioceptive receptors . thirdly , the protective extension response involves a movement by an extremity or combination of movements that changes the bos to accommodate the position of the cog or cob to bring the cog or cob within the new bos . an example of this would be when someone reaches out their arm to stop or break them from falling , either in the sitting or standing position . both the mitts 12 and cuffs 10 are designed to allow for the attachment to an elastic - resistive cord 28 to allow for dynamic elastic - resistive exercising in the water . this unique feature allows for the selection of varying amounts of resistance dependent on the tension generated during exercise . optimal strengthening and stretching in one &# 39 ; s therapeutic or fitness program can be achieved with the usage of elastic - resistive cords . the cord 28 is anchored to an attachment point 50 , such as an eyelet for a lane line or even wrapped around a rail on a ladder . then the hook ends 52 of the tether cord are hooked into the o - rings on the cuffs and / or mitts allowing for the tension to be generated along the long axis of the elastic tether cords . simply stated , when there is more distance between the attachment point and the o - rings on the cuffs and / or the mitts there is more tension generated which directly translates into increased resistance during a movement / exercise . the preferred embodiments can also be used on land for rehabilitative and fitness purposes . the mitts and cuffs must be used in combination with the elastic - resistive tether cords to allow for resistive exercise training on land since the air does not provide enough resistance at the slow speeds attained during usual rehabilitative and fitness programs . it will now be apparent to those skilled in the art that other embodiments , improvements , details , and uses can be made consistent with the letter and spirit of the foregoing disclosure and within the scope of this patent , which is limited only by the following claims , construed in accordance with the patent law , including the doctrine of equivalents .