Patent Publication Number: US-10322312-B1

Title: Resistance and filtration breathing device

Description:
FIELD OF THE INVENTION 
     The present invention relates to wearable breathing devices. More particularly, the present invention relates to wearable breathing masks providing air filtration and resistance to air inhalation. 
     BACKGROUND OF THE INVENTION 
     Individuals who are training for physical fitness or athletic competition may wish to improve the efficiency of their cardiovascular systems for improved health and stamina. Continued exposure to the reduced concentration of oxygen in the atmosphere at higher altitudes provides increased mass of red blood cells, improved efficiency of oxygen use by the muscles, and enhanced lung performance. Individuals may wish to be able to obtain the benefits of training in any desired setting. Individuals may further wish to train in any desired setting without being affected by the air quality present in such a desired setting. 
     SUMMARY OF THE INVENTION 
     In an embodiment a resistance breathing device includes a face mask, an intake restricting element, and an adjustment mechanism, the face mask having an interior surface, an exterior surface opposite the interior surface, and at least one inlet aperture extending from the exterior surface to the interior surface, the intake restricting element including at least one inlet aperture, the intake restricting element being movably positioned adjacent to the face mask, the intake restricting element being movable rotatably between at least a first position, wherein a first portion of the at least one inlet aperture of the intake restricting element overlays a first portion of the at least one inlet aperture of the face mask, and a second position, wherein a second portion of the at least one inlet aperture of the intake restricting element overlays a second portion of the at least one inlet aperture of the face mask, the second portion of the at least one inlet aperture of the intake restricting element being larger in size than the first portion of the at least one inlet aperture of the intake restricting element, the adjustment mechanism attached to the face mask such that the adjustment mechanism is movable between at least a first position and a second position, the first position of the adjustment mechanism corresponding to the first position of the intake restricting element, the second position of the adjustment wheel corresponding to the second position of the intake restricting element. 
     In an embodiment, motion of the adjustment mechanism between its first position and its second position causes corresponding motion of the intake restricting element between its first position and its second position. 
     In an embodiment, the resistance breathing device also includes a filter overlaying the at least one inlet aperture of the face mask. In an embodiment, the adjustment mechanism includes an adjustment wheel. In an embodiment, the intake restricting element includes a first plurality of teeth and the adjustment wheel includes a second plurality of teeth, the intake restricting element and the adjustment wheel being positioned adjacent to one another such that the first plurality of teeth of the intake restricting element meshes with the second plurality of teeth of the adjustment wheel. In an embodiment, the resistance breathing device also includes a retainer movably attached to the face mask, the retainer being movable between at least a first position, wherein the retainer retains the filter in proximity to the face mask, and a second position, wherein the retainer enables the filter to be removed from the face mask. 
     In an embodiment, the face mask includes a plurality of grooves formed in the exterior surface of the face mask and spaced apart from one another, the intake restricting element including an arm extending therefrom and a ridge projecting from the arm, the ridge of the intake restricting element being positioned within a first one of the plurality of grooves of the face mask when the intake restricting element is in its first position, and the ridge of the intake restricting element being positioned within a second one of the plurality of grooves of the face mask when the intake restricting element is in its second position. In an embodiment, the ridge of the intake restricting element and the plurality of grooves of the face mask are sized and shaped such that when the ridge is positioned within one of the plurality of grooves, the ridge and the one of the plurality of grooves cooperate to resist rotational movement of the intake restricting element. In an embodiment, the face mask includes a hole defining a rotational axis, the intake restricting element including a post, and the hole of the face mask receives the post of the intake restricting element such that the rotational movement of the intake restricting element with respect to the face mask is about the rotational axis of the hole. In an embodiment, the at least one inlet aperture of the face mask includes a plurality of inlet apertures and the at least one inlet aperture of the intake restricting element includes a plurality of inlet apertures, each of the plurality of inlet apertures of the intake restricting element corresponds to one of the plurality of inlet apertures of the face mask, when the intake restricting element is in its first position, a first portion of each of the plurality of inlet apertures of the intake restricting element overlays a first portion of the corresponding one of the plurality of inlet apertures of the face mask, and when the intake restricting element is in its second position, a second portion each of the plurality of inlet apertures of the intake restricting element overlays a second portion of the corresponding one of the plurality of inlet apertures of the face mask, the second portion of each of the plurality of inlet apertures of the intake restricting element being larger in size than the first portion of each of the plurality of inlet apertures of the intake restricting element. 
     In an embodiment, the plurality of inlet apertures of the intake restricting element is arrayed about the post of the intake restricting element in an arcuate arrangement. In an embodiment, at least one of the plurality of inlet apertures of the intake restricting element includes an annular sector shape. In an embodiment, the plurality of inlet apertures of the face mask is arrayed about the hole of the face mask in an arcuate arrangement. In an embodiment, at least one of the plurality of inlet apertures of the face mask has an annular sector shape. In an embodiment, each of the plurality of inlet apertures of the intake restricting element is identically sized and shaped to the corresponding one of the plurality of inlet apertures of the face mask. 
     In an embodiment, a size of the at least one inlet aperture of the intake restricting element is equal to a size of the at least one inlet aperture of the face mask. In an embodiment, the resistance breathing device also includes an air exhaust assembly configured to prevent air from passing therethrough from an external environment to an internal area of the face mask and to allow air to pass therethrough from the internal area of the face mask to the external environment. In an embodiment, the air exhaust assembly includes at least one outlet aperture positioned offset from the at least one inlet aperture of the face mask and at least one membrane, each of the at least one membrane overlaying a corresponding one of the at least one outlet aperture so as to allow air to pass through the at least one outlet aperture from the internal area of the face mask to the external environment and to prevent air from passing through the at least one outlet aperture from the external environment to the internal area. 
     In an embodiment, each of the at least one outlet aperture includes a biasing member extending across the one of the at least one outlet aperture of the face mask and a stem extending from a center of the biasing member and away from the face mask, wherein each of the at least one membrane has a hole extending therethrough, and wherein the stem of each of the at least one outlet aperture is positioned within the hole of the corresponding one of the at least one membrane. In an embodiment, the stem of each of the at least one outlet aperture includes a first portion adjacent the stem of biasing member and a second portion opposite the first portion of the stem, the second portion of the stem having a second diameter that is larger than the first diameter, and wherein the second portion of the stem retains the corresponding one of the at least one membrane adjacent the biasing element of the at least one outlet aperture. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference is made to the following detailed description of the exemplary embodiment considered in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a front elevational view of a resistance and filtration breathing device in accordance with a first exemplary embodiment of the present invention, said device being shown as worn by a user; 
         FIG. 2  is a front perspective view of the resistance and filtration breathing device shown in  FIG. 1 , but said device being shown as detached from the user; 
         FIG. 3  is a rear perspective view of the resistance and filtration breathing device shown in  FIG. 2 ; 
         FIG. 4A  is a front perspective view of selected elements of the resistance and filtration breathing device shown in  FIG. 2 ; 
         FIG. 4B  is a rear perspective view of the elements shown in  FIG. 4A ; 
         FIG. 5A  is an exploded front perspective view of selected elements of the resistance breathing device shown in  FIG. 2 ; 
         FIG. 5B  is an exploded rear perspective view of the elements shown in  FIG. 5A ; 
         FIG. 6A  is an assembled front perspective view of some of the elements shown in  FIG. 5A , said elements being configured in a first position; 
         FIG. 6B  is an assembled front perspective view of the elements shown in  FIG. 6A , said elements being configured in a second position; and 
         FIG. 6C  is an assembled front perspective view of the elements shown in  FIG. 6A , said elements being configured in a third position. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
       FIGS. 1-6C  illustrate an exemplary resistance and filtration breathing device  10  (hereinafter “device  10 ” for brevity). In an embodiment, the device  10  includes an outer layer  12  overlaying a centrally-located, air-impermeable face mask  14 . In an embodiment, the face mask  14  is sized, shaped, and adapted to overlay the nose and mouth of a user. In an embodiment, the face mask  14  includes a perimeter  16  (as shown in  FIG. 3 ) that is adapted to provide an air-tight seal with a user&#39;s face. In an embodiment, the face mask  14  is made from rubber. In another embodiment, the face mask  14  is made from other suitable materials known in the art selected such that the perimeter  16  provides an air-tight seal with a user&#39;s face. Referring now to  FIGS. 2 and 3 , in an embodiment, the face mask  14  includes an interior surface  18  and an exterior surface  20 . Referring now to  FIG. 4 , in an embodiment, the face mask  14  includes an aperture  22  extending from the interior surface  18  to the exterior surface  20 . In an embodiment, the aperture  22  is encircled by a lip  24 . In an embodiment, the lip  24  includes a groove  26  formed therein and extending about the entirety thereof. 
     Referring now to  FIGS. 4A and 4B , in an embodiment, the device  10  includes an insert  30  having an interior surface  32 , an exterior surface  34 , and a perimeter surface  36  encircling an entire perimeter of the interior and exterior surfaces  32 ,  34 . In an embodiment, the insert  30  has a profile similar to a rounded triangle. In an embodiment, the insert  30  has a profile similar to that of a region overlaying a person&#39;s nose and mouth. In an embodiment, an interior flange  38  extends from the perimeter surface  36  proximate the interior surface  32 . In an embodiment, an exterior flange  40  extends from the perimeter surface  36  proximate the exterior surface  34 . In an embodiment, an array of perforations  42  extends through the interior flange  38 . In an embodiment, the interior flange  38 , intermediate flange  40 , and exterior flange  42  each encircle the entire perimeter surface  36 . In an embodiment, the perimeter surface  36  is sized and shaped so as to be complementary with the aperture  20  of the face mask  12 . In an embodiment, the interior and intermediate flanges  38 ,  40  are sized, shaped, and positioned so as to retain the lip  24  of the face mask  12  therebetween and form an air-tight seal therewith. In an embodiment, the insert  30  is removably inserted into the aperture  22  of the face mask  14 , so as to provide such benefits as easy cleaning and interchangeability of components of the device  10 . 
     Continuing to refer to  FIGS. 4A and 4B , in an embodiment, the perimeter surface  36  includes an upper end  44  and a lower end  46 . In an embodiment, a ridge  50  protrudes from the exterior surface  34 , extends from the upper end  44  to the lower end  46  of the perimeter surface  36 , and divides the exterior surface  34  into a first side  52  and a second side  54 . In the embodiment described herein, the exterior surface  34  is divided laterally into a first portion that is a first side  52  and a second portion that is a second side  54 , but it will be apparent to those of skill in the art that other types of divisions into two portions are available, including vertically, diagonally, concentrically, etc. are possible without departing from the broader principle of the exemplary device  10 . In an embodiment, an indentation  138  is formed within the perimeter surface  36  at the upper end  44 . 
     Continuing to refer to  FIGS. 4A and 4B , in an embodiment, the insert  30  includes seats  56 ,  58 ,  60 ,  62  disposed on the first side  52  of the exterior surface  34 . It will be apparent to those of skill in the art that the inclusion of four seats  56 ,  58 ,  60 ,  62  is only exemplary and that other embodiments of a device  10  may include a larger or smaller quantity of seats. In an embodiment, the seats  56 ,  58 ,  60 ,  62  include corresponding cylindrical perimeter surfaces  64 ,  66 ,  68 ,  70  projecting from the exterior surface  34  of the insert  30 . in an embodiment, The perimeter surfaces  64 ,  66 ,  68 ,  70  extends to corresponding substantially planar upper surfaces  72 ,  74 ,  76 ,  78  having corresponding circular apertures  80 ,  82 ,  84 ,  86  extending therethrough from the exterior surface  34  to the interior surface  32 . In an embodiment, the seats  56 ,  58 ,  60 ,  62  also include corresponding biasing elements  88 ,  90 ,  92 ,  94  disposed within the corresponding apertures  80 ,  82 ,  84 ,  86  and having corresponding centers  96 ,  98 ,  100 ,  102 . In the exemplary embodiment described herein, the biasing elements  88 ,  90 ,  92 ,  94  are plus-shaped, but it will be apparent to those of skill in the art that other shapes are possible. In an embodiment, the seats  56 ,  58 ,  60 ,  62  also include corresponding posts  104 ,  106 ,  108 ,  110  extending from the centers  96 ,  98 ,  100 ,  102  of the corresponding biasing elements  88 ,  90 ,  92 ,  94 . 
     Continuing to refer to  FIGS. 4A and 4B , in an embodiment, the insert  30  includes apertures  112 ,  114 ,  116 ,  118 ,  120  formed within the second side  54  of the exterior surface  34  and extending therethrough from the exterior surface  34  to the interior surface  32 . In an embodiment, each of the apertures  112 ,  114 ,  116 ,  118 ,  120  has a profile of an annulus sector (i.e., is the shape of a sector of an annulus). In an embodiment, the apertures  112 ,  114 ,  116 ,  118 ,  120  are arrayed in an arcuate (e.g., fan-like) shape. It will be apparent to those of skill in the art that the inclusion of five apertures  112 ,  114 ,  116 ,  118 ,  120  is only exemplary and that other embodiments of a device  10  may include a larger or smaller quantity of apertures. In an embodiment, a gap  122  is formed is formed in the exterior flange  42  at a location proximate the lower end  46  and the second side  54  of the insert  30 . 
     In an embodiment, a post  124  extends from the second side  54  of the exterior surface  34  at or about the center of the gap  122 . In an embodiment, an axial bore  125  extends through the post  124 . In an embodiment, a hole  126  extends through the second side  54  of the exterior surface  34  at a location intermediate the upper and lower ends  44 ,  46  and proximate the ridge  50 . In an embodiment, the apertures  112 ,  114 ,  116 ,  118 ,  128  are arrayed about the hole  126  in an arcuate arrangement. In an embodiment, a plurality of stops  128  extends from the second side  54  of the exterior surface  34 . In an embodiment, the plurality of stops  128  includes four of the stops  128 , but other numbers of the stops  128  may be present in other embodiments. In an embodiment, a clasp  130  extends from the exterior flange  42  and is located near the second side  54 , intermediate the upper and lower ends  44 ,  46 , and extending toward the ridge  50 . In an embodiment, a guide  132  extends from the second side  54  of the exterior surface  34  proximate the clasp  130 . In an embodiment, a plurality of grooves  134  is formed in the second side  54  of the exterior surface  34  proximate the ridge  50  and intermediate the upper end  44  and the hole  126 . In an embodiment, the plurality of grooves  134  includes six of the grooves  134 , but other numbers of the grooves  134  may be present in other embodiments. In an embodiment, a catch  136  projects away from the ridge  50  toward the second side  54  from a location on the ridge  50  that is proximate the lower end  46  of the perimeter surface  36 . The functions of the post  124 , the bore  125 , the hole  126 , the stops  128 , the clasp  130 , the guide  132 , the grooves  134 , and the catch  136  will be described hereinafter. 
     Continuing to refer to  FIGS. 4A and 4B , in an embodiment, the device  10  includes flexible, air-impermeable, disc-shaped membranes  140 ,  142 ,  144 ,  146 . Each of the membranes  140 ,  142 ,  144 ,  146  corresponds to one of the seats  56 ,  58 ,  60 ,  62 ; therefore, in an embodiment of a device  10  that includes a different quantity of seats, the quantity of membranes will vary accordingly. In an embodiment, the membranes  140 ,  142 ,  144 ,  146  include corresponding central apertures  150 ,  152 ,  154 ,  156 , respectively, that are sized and shaped to receive the posts  104 ,  106 ,  108 ,  110  of the corresponding seats  56 ,  58 ,  60 ,  62  so as to be mounted thereon, and are sized and shaped such that, when mounted on the corresponding posts  104 ,  106 ,  108 ,  110 , each the membranes  140 ,  142 ,  144 ,  146  covers the circular aperture  80 ,  82 ,  84 ,  86  of the corresponding one of the seats  56 ,  58 ,  60 ,  62 . 
     Continuing to refer to  FIGS. 4A and 4B , in an embodiment, the device  10  includes a filter  160  that is sized and shaped so as to be complementary to the second side  54  of the exterior surface  34  of the insert  30 . In an embodiment, the filter  160  provides filtration of substantially all airborne particles from air inhaled and exhaled therethrough. In an embodiment, the filter  160  is a filter meeting the standards of the N100 class of filters defined by the National Institute for Occupational Safety and Health (“NIOSH”). In an embodiment, the filter  160  is capable of filtering at least 99.97% of airborne particles (e.g., dust, sand, etc.) in air passing therethrough. In an embodiment, the filter  160  includes multiple layers that are affixed to one another by a binding. In an embodiment, the binding may be formed by heat bonding. In another embodiment, the binding may include stitching. However, those of skill in the art will understand that the specific aspects of the filter  160  described above (e.g., the use of a layered construction, the quantity of layers, the manner of binding of the layers) are only exemplary and that other arrangements are possible without departing from the broader concepts embodied thereby. In an embodiment, the device  10  may include two or more different interchangeable filters  160  to enable the user to customize the degree and type of filtration provided thereby. In an embodiment, the device  10  may include two or more identical interchangeable filters  160  to enable the user to replace the filter  160  after a prescribed amount of usage, to thereby maintain adequate filtration and prevent performance degradation. In an embodiment, the device  10  may include a single filter  160 , but other filters may be made separately available for replacement of the included filter  160  as described above. 
     Referring now to  FIGS. 5A and 5B , in an embodiment, the device  10  includes an intake restricting element  180 . In an embodiment, the intake restricting element  180  has a body  182 . In an embodiment, the body  182  has a first straight side  184 , a second straight side  186 , and a curved side  188  that, together, form a general profile that is shaped like a sector of a circle (i.e., the body  182  is generally wedge-shaped). In an embodiment, a post  190  extends from the body  182  of the intake restricting element  180  at a location that is approximately at the intersection of the first and second straight sides  184 ,  186  and in a direction that is generally perpendicular to the first and second straight sides  184 ,  186 . In an embodiment, the post  190  is configured to be inserted into the hole  126  of the insert  30  in a manner such that the intake restricting element  180  can rotate about the hole  126 . Such rotation may be described as rotation about a rotational axis extending through the hole  126  and perpendicular to the exterior surface  52  of the insert  30 . In an embodiment, the post  190  may be press fit into hole  126 . In an embodiment, the post  190  may be secured by forming a bulb proximate the interior surface  32  of the insert  30 . In another embodiment, the insert  30  includes a post in place of the hole  126 , the intake restricting element  180  includes a hole in place of the post  190 , and the intake restricting element  180  may engage the insert  30  by inserting the post of the insert  30  into the hole of the intake restricting element  180 . 
     Continuing to refer to  FIGS. 5A and 5B , in an embodiment, a plurality of apertures  200 ,  202 ,  204 ,  206  extend through the body  182  of the intake restricting element  180 . In an embodiment, each of the apertures  200 ,  202 ,  204 ,  206  has a profile of an annulus sector (i.e., is the shape of a sector of an annulus). In an embodiment, the plurality of apertures  200 ,  202 ,  204 ,  206  are arrayed about the post  190  in an arcuate (e.g., fan-like) arrangement. In an embodiment, the plurality of apertures are sized, shaped, and positioned such that, when the post  190  of the body  182  receives the post  126  of the insert  30 , at least a portion of each of the apertures  200 ,  202 ,  204 ,  206  overlays at least a portion of a corresponding one of the apertures  112 ,  114 ,  116 ,  118 ,  120  of the insert  30 . In an embodiment, each of the apertures  200 ,  202 ,  204 ,  206  is sized and shaped substantially identically to the corresponding one of the apertures  112 ,  114 ,  116 ,  118 ,  120  of the insert  30 . In an embodiment, the size of the overlaying portions varies based on the rotational orientation of the intake restricting element  180  with respect to the insert  30 . In an embodiment, a rib  208  extends circumferentially about the post  190 , from the first straight side  184  to the second straight side  186 , bisecting each of the apertures  200 ,  202 ,  204 ,  206 . In an embodiment, the rib  208  is sized and shaped to strengthen and stabilize the intake restricting element  180 . 
     Continuing to refer to  FIGS. 5A and 5B , in an embodiment, a plurality of teeth  210  extends radially outward from the curved side  188  of the body  182  of the intake resisting element  180 . In an embodiment, the teeth  210  are positioned such that, when the hole  126  of the insert  30  receives the post  190  of the body  182 , the teeth  210  extend generally toward the post  124  of the insert  30 . In an embodiment, an arm  212  extends outward from the first straight side  184  of the body  182 . In an embodiment, the arm  212  is positioned proximate the curved side  188  of the body  182  and extends in a circumferential direction away from the second straight side  186  of the body  182 . In an embodiment, a ridge  214  extends from the arm  212 . In an embodiment, the arm  212  and the ridge  214  are sized, shaped, and positioned such that, when the hole  126  of the insert  30  receives the post  190  of the body  182 , the ridge  214  is positioned generally proximate the grooves  134  of the insert  30 , and may variably be aligned with one of the grooves  134 , or be positioned between two adjacent ones of the grooves  134 , or be positioned past a first or last one of the grooves  134 , depending on the rotational alignment of the intake resisting element  180  with respect to the insert  30 . In an embodiment, the arm  212  may abut the ridge  50  of the insert  30  to restrict the rotational travel of the intake resisting element  180  in one direction. In an embodiment, a fin  216  extends radially outward from the curved side  188  of the body  182 . In an embodiment, the fin  216  is sized, shaped, and positioned such that, when the hole  126  of the insert  30  receives the post  190  of the body  182 , the guide  132  of the insert  30  overlays the fin  216 , thereby guiding rotation of the intake resisting element  180  with respect to the insert  30 . 
     In an embodiment, rather than the grooves  134 , the insert  30  may include a series of ridges positioned in the same region of the second side  54  as are the grooves  134 . In such an embodiment, the ridge  214  of the arm  212  of the intake restricting element  180  may be positioned between adjacent ones of such ridges to define discrete positional settings for the intake restricting element  180 . In such an embodiment, the ridge  214  of the arm  212  of the intake restricting element  180  may be aligned with various ones of such ridges to define transitions between such discrete positional settings. 
     Continuing to refer to  FIGS. 5A and 5B , in an embodiment, the device  10  includes an adjustment wheel  220  (e.g., an adjustment mechanism). The adjustment wheel  220  includes a substantially circular body  222  having an interior surface  224  and an exterior surface  226  opposite the interior surface  224 . A hole  228  extends through the body  222  and is positioned concentrically therewith. The hole  228  is sized and shaped to receive the post  124  of the insert  30  in a complementary manner, such that the adjustment wheel  220  cannot move across the exterior surface  44  of the insert  30 , but can rotate with respect to the insert  30 . Such rotation may be described as rotation about a rotational axis extending through the post  124  and perpendicular to the exterior surface  52  of the insert  30 . The body  222  includes a first side  230  and a second side  232  opposite the first side  230 . A plurality of teeth  234  extend from the first side  230  of the body  222 , and are sized and shaped so as to mesh with the teeth  210  extending from the curved side  188  of the intake restricting element  180 . A plurality of grips  236  extend from the second side  232  of the body  222 , and are sized and shaped so as to enable a user of the device  10  to rotate the adjustment wheel  220  in a manner that will be described in further detail hereinafter. In an embodiment, indicia are printed on the exterior surface  226  of the body  222 . 
     Continuing to refer to  FIGS. 5A and 5B , in an embodiment, the device  10  includes a rivet  238 . In an embodiment, the rivet  238  is configured to be fixed in the hole  125  of the insert  30 . 
     Continuing to refer to  FIGS. 5A and 5B , in an embodiment, the device  10  includes a retainer  240 . In an embodiment, the retainer  240  has a profile that generally conforms to that of the second side  54  of the exterior surface  34  of the insert, and has a generally lattice-like structure that allows air to pass freely therethrough. In an embodiment, the retainer  240  includes a mounting portion  242  that is sized and shaped to be received by the clasp  130  of the insert  30  in a manner such that the retainer  240  can be rotated about the clasp  130  between a first position, in which the retainer  240  overlays the second side  54  and the intake restricting element  180 , and a second position, in which the retainer  240  is moved away from the second side  54  so as to allow access to the intake restricting element  180 . In an embodiment, the retainer  240  includes a groove  244  that is sized, shaped, and positioned so as to engage the catch  136  protruding from the ridge  50  of the insert  30  when the retainer  240  is in its first position, thereby providing resistance to motion of the retainer  240  away from its first position. In an embodiment, the retainer  240  includes first and second cutouts  246 ,  248  that are sized, shaped, and positioned so as to overlay the post  124  and the hole  126 , respectively, of the second side  54  of the exterior surface  34  of the insert  130 . 
     Continuing to refer to  FIGS. 5A and 5B , in an embodiment, the device  10  includes a cap  250  having a profile similar to that of the insert  30 . In an embodiment, the cap  250  has an interior surface  252 , an exterior surface  254 , an upper end  256 , and a lower end  258  opposite the upper end  256 . In an embodiment, a flange  260  extends about the entire perimeter of the interior surface  252 . In an embodiment, the flange  260  is sized and shaped to be complementary to the exterior flange  42  extending from the perimeter surface  36  of the insert  30 , and thereby to facilitate attachment of the cap  250  to the insert  30 . In an embodiment, the cap  250  is removably attached to the insert  30  to enable access to the internal elements of the device  10  (e.g., to enable replacement of the filter  160 ). In an embodiment, the cap  250  is permanently attached to the insert  30 , such as through the use of an adhesive. In an embodiment, a projection  262  extends inwardly from the flange  260  at the upper end  256  of the cap  250  and is sized and shaped to be received within the indentation  138  of the insert  30 . 
     Continuing to refer to  FIGS. 5A and 5B , in an embodiment, the cap  250  includes a hole array  262  having a plurality of holes  264 , each of which extends through the cap  250  from the interior surface  252  to the exterior surface  254 .  FIGS. 5A and 5B  indicate only a single one of the holes  264  for the sake of clarity, but it will be apparent to those of skill in the art that the disclosure of a hole  264  or of holes  264  may refer to any of the holes  264  described herein and illustrated in  FIGS. 5A and 5B . It will also be apparent to those of skill in the art that the specific size, shape, and positioning of the holes  264  forming the hole array  262  shown in  FIGS. 1, 5A and 5B  is only exemplary. In an embodiment, the hole array  262  is arranged so as to provide an aesthetically pleasing appearance to the device  10 . In an embodiment, the hole array  262  is arranged in a substantially U-shaped arrangement. 
     Referring back to  FIGS. 2 and 3 , in an embodiment, the outer layer  12  includes straps  270 ,  272  extending in opposite directions away from a central portion  274 . In an embodiment, the central portion  274  includes an aperture  276  that is sized and shaped to surround the perimeter surface  36  of the insert  30  and retain the insert  30  therein. In an embodiment, the outer layer  12  is made from a fabric material. In an embodiment, the outer layer  12  is made from an elastic material. In an embodiment, the size of the outer layer  12  is adjustable (e.g., the lengths of the straps  270 ,  272  are adjustable). In an embodiment, the straps  270 ,  272  include corresponding ends  278 ,  280 . In an embodiment, the ends  278 ,  280  of the straps  270 ,  272  incorporate corresponding hook and loop fasteners  282 ,  284  to enable the ends  278 ,  280  to be secured to one another, thereby to enable the device  10  to be affixed about the user&#39;s head (see, e.g.,  FIG. 1 ). In other embodiments, the ends  278 ,  280  of the straps  270 ,  272  include other securing means known in the art, such as clips, press-fit snaps, buttons, or the like. In an embodiment, the straps  270 ,  272  include cutouts  286 ,  288  for seating around the user&#39;s ears to further secure the device  10  to the user&#39;s face. 
     In an embodiment, at least one of the insert  30 , the intake restricting element  180 , the adjustment wheel  220 , the retainer  240 , and the cap  250  is made from a polycarbonate (“PC”) plastic. In an embodiment, at least one of the insert  30 , the intake restricting element  180 , the adjustment wheel  220 , the retainer  240 , and the cap  250  is made from a nylon plastic. In an embodiment, at least one of the insert  30 , the intake restricting element  180 , the adjustment wheel  220 , the retainer  240 , and the cap  250  is made from a polypropylene plastic. In an embodiment, at least one of the insert  30 , the intake restricting element  180 , the adjustment wheel  220 , the retainer  240 , and the cap  250  is made from another material selected such that they are capable of use as described herein. In an embodiment, all of the insert  30 , the intake restricting element  180 , the adjustment wheel  220 , the retainer  240 , and the cap  250  are made from the same material. In an embodiment, one or more of the insert  30 , the intake restricting element  180 , the adjustment wheel  220 , the retainer  240 , and the cap  250  is made from a different material. In an embodiment, at least one of the insert  30 , the intake restricting element  180 , the adjustment wheel  220 , the retainer  240 , and the cap  250  is made from a translucent material. In an embodiment, at least one of the insert  30 , the intake restricting element  180 , the adjustment wheel  220 , the retainer  240 , and the cap  250  is made from an opaque material. 
     Referring now to  FIGS. 5A-6C , assembly of the device  10  is described. The insert  30  is inserted into the aperture  22  of the face mask  14  such that the lip  24  of the face mask  14  is received between the interior flange  38  and intermediate flange  40  of the insert  30 . The elastic nature of the face mask  14  retains the insert  30  within the aperture  22  in an airtight engagement. In an embodiment, the face mask  14  and the insert  30  are integrally formed with one another by an overmolding process. When the face mask  14  and the insert  30  are so formed, the entire periphery of the interior flange  38  of the insert  30  is disposed within the groove  26  of the lip  24  of the face mask  14 , and the material of the face mask  14  extends through each of the perforations  42  that are formed in the interior flange  38  of the insert  30 . The elastic nature of the face mask  14 , coupled with the overmolding as described above, retains the insert  30  within the aperture  22  (and, more particularly, within the groove  26 ) in an engagement that is air-tight and structurally secure. However, for clarity of illustration, the face mask  14  is not shown in  FIGS. 4A-5C . 
     Continuing to refer to  FIGS. 5A-6C , the membranes  140 ,  142 ,  144 ,  146  are affixed to the insert  30  by placing the central apertures  150 ,  152 ,  154 ,  156  thereof over the corresponding posts  104 ,  106 ,  108 ,  110 . In an embodiment, the posts  104 ,  106 ,  108 ,  110  include bulbous portions opposite the corresponding biasing elements  88 ,  90 ,  92 ,  94 , which are configured to retain the membranes  140 ,  142 ,  144 ,  146  thereon. 
     Continuing to refer to  FIGS. 5A-6C , the intake restricting element  180  is positioned over the insert  30  by positioning the fin  216  of the intake restricting element  180  under the guide  132  of the insert  30 , then lowering the post  190  of the intake restricting element  180  into the hole  126  of the insert  30 . The adjustment wheel  220  is positioned over the insert by lowering the hole  228  of the adjustment wheel  220  over the post  124  of the insert  30  while the teeth  234  of the adjustment wheel  220  are positioned so as to mesh with the teeth  210  of the intake restricting element  180 . The rivet  238  is secured in the bore  125  of the insert  30  to affix the adjustment wheel  220  to the insert  30 . The post  190  of the intake restricting element  180  is secured in the hole  126  of the insert  30  by “heat staking,” i.e., by melting a portion of the post  190  at an end of the post  190  that protrudes past the interior surface  32  of the insert  30 , thereby to form a cap that retains the post  190  in proximity to the insert  30 . 
     Continuing to refer to  FIGS. 5A-6C , the retainer  240  is attached to the insert  30  by positioning the mounting portion  242  of the retainer  240  within the clasp  130  of the insert  30 . The filter  144  is placed over the intake restricting element  180  and is secured in place by pivoting the retainer  240  to the first position discussed above, such that the groove  244  of the retainer  240  receives the catch  136  of the insert  30 , thereby retaining the retainer  240  in the first position and securing the filter  144  in proximity to the intake restricting element  180 . 
     Referring now to  FIGS. 1-3 , the cap  250  is engaged to the insert  30  by engaging the flange  260  of the cap  250  with the exterior flange  42  of the insert  30 . During such engagement, the projection  262  of the cap  250  may be aligned with the indentation  138  in the perimeter surface  36  of the cap to facilitate proper alignment of the cap  250  with respect to the insert  30 . The cap  250  may be permanently fixed to the insert  30  (e.g., through the use of an adhesive), or may be removable therefrom. The outer layer  12  is laid over the face mask  14 , which has the insert  30  retained therein. The aperture  276  of the outer layer  12  is stretched and placed over the insert  30  such that the aperture  276  surrounds the perimeter surface  36  of the insert  30 , and then allowed to return to its relaxed (i.e., not stretched) size such that the aperture  276  of the outer layer  12  retains the insert  30 , and thus the face mask  14 , therein. 
     Referring now to  FIGS. 1 and 6A through 6C , use of the exemplary device  10  by a user according to an exemplary embodiment will now be described. Initially, the device  10  is affixed to the user&#39;s face by placing the face mask  14  over the user&#39;s mouth and nose, passing the straps  270 ,  272  around either side of the user&#39;s head such that the cutouts  286 ,  288  overlap the user&#39;s ears, and securing the ends  278 ,  280  to one another using the hook and loop fasteners  282 ,  284 . The user may adjust the hook and loop fasteners  282 ,  284  to ensure that the face mask  14  is pulled against the user&#39;s face with sufficient force such that the perimeter  16  thereof is pressed tightly against the user&#39;s face and around the user&#39;s mouth and nose. By such action, an airtight seal is created between the user&#39;s face and the face mask  14 , thereby ensuring that air can only pass in and out for the user&#39;s inhalation and exhalation through the various apertures formed within the insert  30 . 
     Referring now to  FIGS. 6A through 6C , adjustment of the exemplary device  10  by a user will now be described. More particularly,  FIGS. 6A, 6B, and 6C  illustrate certain elements of the device  10  (including the insert  30 , the intake restricting element  180 , and the adjustment wheel  240 ) with other elements of the device  10  (including, most relevantly, the cap  250 ) omitted for clarity.  FIG. 6A  shows a first position of the intake restricting element  180  with respect to the insert  30 . Specifically, the intake restricting element  180  is positioned such that the arm  212  abuts the ridge  50  of the insert  30 . When the intake restricting element  180  is so positioned, the ridge  214  of the arm  212  is aligned with and rests within the one of the grooves  134  that is closest to the ridge  50 . Also, when the intake restricting element  180  is so positioned, each of the apertures  200 ,  202 ,  204 ,  206  of the intake restricting element  180  overlaps the entirety of a corresponding one of the apertures  112 ,  114 ,  116 ,  118  of the insert  30  and the intake restricting element  180  does not cover the aperture  120  of the insert  30 , which does not correspond to any of the apertures  200 ,  202 ,  204 ,  206  of the intake restricting element  180 . Consequently, a comparatively large volume of air may pass through the aligned pairs of the apertures  200 ,  202 ,  204 ,  206  of the intake restricting element  180  with the corresponding one of the apertures  112 ,  114 ,  116 ,  118  of the insert  30  and through the exposed aperture  120  of the insert  30 . 
     Referring now to  FIG. 6B , in some circumstances, the user may wish to decrease the volume of air that may pass into the face mask  14 . In this case, the user may manipulate the adjustment wheel  220 , with the grips  236  aiding the user&#39;s ability to do so, and may rotate the adjustment wheel  220  in a counterclockwise direction as viewed from the perspective shown in  FIGS. 6A through 6C . Such rotation of the adjustment wheel  220  and, consequently, the teeth  234  thereof drives corresponding motion of the teeth  210  of the intake restricting element  180 , thereby causing the corresponding clockwise rotation of the intake restricting element  180 . As the intake restricting element  180  rotates in a direction such that the arm  212  moves away from the ridge  50  of the insert  30 , a smaller portion of each of the apertures  200 ,  202 ,  204 ,  206  of the intake restricting element  180  will overlap the corresponding one of the apertures  112 ,  114 ,  116 ,  118  of the insert  30  and a portion of the intake restricting element  180  covers the aperture  120  of the insert  30 . Consequently, a correspondingly smaller volume of air may pass through the aligned pairs of the apertures  200 ,  202 ,  204 ,  206  of the intake restricting element  180  with the corresponding one of the apertures  112 ,  114 ,  116 ,  118  of the insert  30  and the exposed portion of the aperture  120  of the insert  30 . Referring now to  FIG. 6B , the intake restricting element  180  is shown in an intermediate position in which the ridge  214  of the arm  212  is aligned with and rests within an intermediate one of the grooves  134  of the insert  30 . 
     Referring now to  FIG. 6C , if the user wishes to allow an even smaller degree of air flow into the face mask  14 , the user may continue to rotate the adjustment wheel  220  until the intake restricting element  180  has been driven to such an extent that the arm  212  has moved as far as possible away from the ridge  50  of the insert  30 . In some embodiments, at least one of the stops  128  of the insert  30  defines such maximum allowable travel. When the intake restricting element  180  is so positioned, only a very small portion of each of the apertures  200 ,  202 ,  204 ,  206  of the intake restricting element  180  overlaps the corresponding one of the apertures  112 ,  114 ,  116 ,  118  of the insert  30 , and only a very small portion of the aperture  120  of the insert  30  is exposed by the intake restricting element  30 . Consequently, a still smaller volume of air may pass through the aligned pairs of the apertures  200 ,  202 ,  204 ,  206  of the intake restricting element  180  with the corresponding one of the apertures  112 ,  114 ,  116 ,  118  of the insert  30  and the exposed portion of the aperture  120  of the insert  30 . Continuing to refer to  FIG. 6C , the intake restricting element is shown in a position in which the ridge  214  of the arm  212  rests in the one of the grooves  134  that is furthest from the ridge  50  of the insert  30 . 
     Referring now to  FIGS. 1 through 6C , when the user inhales, a reduced air pressure is induced within the face mask  14  as compared to the surrounding atmosphere. This reduced air pressure urges the membranes  140 ,  142 ,  144 ,  146  against the corresponding biasing elements  88 ,  90 ,  92 ,  94 , in which position the membranes  140 ,  142 ,  144 ,  146  completely overlap and seal the corresponding apertures  80 ,  82 ,  84 ,  86 . Due to such sealing, air cannot pass from the user&#39;s surroundings to within the face mask  14  through the apertures  80 ,  82 ,  84 ,  86 . As a result, the only air that can pass from the user&#39;s surroundings to within the face mask  14  is air allowed to pass through the portions of the apertures  112 ,  114 ,  116 ,  118  of the insert  30  that are aligned with the corresponding apertures  200 ,  202 ,  204 ,  206  of the intake restricting element, or through the portion of the aperture  120  of the insert  30  that is not covered by the intake restricting element  180 . As described above, the user of the device  10  may configure the size of the portions of the apertures  112 ,  114 ,  116 ,  118 ,  120  of the insert that are exposed in this manner by rotating the adjustment wheel  220  to drive corresponding rotation of the intake restricting element  180  with respect to the insert  30 . Therefore, by adjusting the position of the adjustment wheel  220 , the user of the device  10  may control the amount of air that the device  10  allows him or her to inhale. 
     Continuing to refer to  FIGS. 1 through 6C , when the user exhales, an increased air pressure is induced within the face mask  14  as compared to the surrounding atmosphere. This increased air pressure urges the membranes  140 ,  142 ,  144 ,  146  away from corresponding biasing elements  88 ,  90 ,  92 ,  94  of the insert  30 , in which position the membranes  140 ,  142 ,  144 ,  146  do not seal the circular apertures  80 ,  82 ,  84 ,  86  of the insert  30 . Due to such lack of sealing, exhaled air can freely pass from within the face mask  14  to the user&#39;s surroundings through the circular apertures  80 ,  82 ,  84 ,  86  of the insert  30  and the slots  304  of the face plate  280 . Because the combination of the membranes  140 ,  142 ,  144 ,  146 , the biasing elements  88 ,  90 ,  92 ,  94 , and the circular apertures  80 ,  82 ,  84 ,  86  cooperate to allow the user exhale freely therethrough, while preventing air inhalation therethrough, this combination of elements may be considered to form an air exhaust valve assembly. 
     The resistance breathing device  10  restricts the volume of air that can be inhaled by a user during ventilation to the volume of air that can pass through the portions of the apertures  112 ,  114 ,  116 ,  118 ,  120  of the insert  30  that are not obscured by the intake restricting element  180 . Consequently, the resistance breathing device  10  restricts the oxygen available to the user&#39;s body when the device  10  is worn by the user. Users who wear the resistance breathing device  10  during physical training may realize improved benefits from such physical training due to such restriction. Moreover, because the user may select the position of the intake restricting element  180  as described above, and thereby select the sizes of the portions of the apertures  112 ,  114 ,  116 ,  118 ,  120  of the insert  30  that are not obscured by the intake restricting element  180 , the user may select the degree of restriction of inhalation of oxygen to be provided by the resistance breathing device  10 . 
     As the filter  160  overlays the apertures  112 ,  114 ,  116 ,  118 ,  120  of the insert  30 , any air that passes from outside the face mask  14  to within the face mask  14  through the apertures  112 ,  114 ,  116 ,  118 ,  120  is filtered by the filter  160 . As a result, airborne particulate matter (e.g., dust, sand, etc.) is filtered therefrom. Because of the air-tight seal between the perimeter  16  of the face mask  14  and the user&#39;s face, and because of the sealing of the circular apertures  80 ,  82 ,  84 ,  86  of the insert  30  by the corresponding membranes  140 ,  142 ,  144 ,  146  when the user inhales, air passing through the filter  160  is the only air that may pass from outside the device  10  to within the face mask  14  and be inhaled by the user. As a result, the air inhaled by the user may be substantially free of particulate matter, preventing such particulate matter from entering the user&#39;s throat and lungs and causing symptoms such as coughing and congestion. 
     It will be understood that the embodiments described herein are merely exemplary and that a person skilled in the art may make many variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention, as embodied in the appended claims presented.