Patent Publication Number: US-2023158358-A1

Title: Adjustable dumbbell system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 17/568,882, filed Jan. 5, 2022, which claims priority to and the benefit of U.S. Provisional Patent Application No. 63/134,036, filed on Jan. 5, 2021. This application also claims priority to and the benefit of U.S. Provisional Patent Application No. 63/298,170, filed on Jan. 10, 2022, which are hereby incorporated by reference in their entireties. 
    
    
     BACKGROUND 
     Background and Relevant Art 
     Muscle training may involve a user moving weights, often called dumbbells, in specific motions to tone body muscles. Different muscle groups may be exercised with different amounts of weight. Indeed, the same muscle group may be exercised with different amounts of weights. Fixed dumbbells have a fixed weight. A collection of fixed dumbbells may be expensive, and may require a large amount of storage space. Adjustable dumbbells allow a user to add or remove weight plates from a handle to customize the weight of the dumbbell. This may save the user money, by requiring a smaller amount of weights to be purchased, and may save the user space by requiring a smaller storage space. 
     BRIEF SUMMARY 
     In some embodiments, a system for securing an adjustable dumbbell includes a handle. A plate adjustment mechanism is configured to selectively connect a selected weight plate of a plurality of weight plates to the handle. Each weight plate includes a notch. A cradle is configured to receive the plurality of weight plates, the cradle includes a latch. A retention mechanism is configured to selectively engage the latch with the notch of an unselected weight plate. The handle adjustment mechanism is mechanically connected to the cradle adjustment mechanism 
     In other embodiments, a system for securing an adjustable dumbbell includes a handle. A plurality of weight plates are removably connected to the handle. Each weight plate includes a notch. A cradle includes a plurality of weight plate receptacles. Each weight plate receptacle is configured to receive each weight plate of the plurality of weight plates. A plurality of latches are configured to be selectively inserted into the notch. The plurality of latches are individually actuated. 
     In yet other embodiments, a method for securing an adjustable dumbbell includes placing a dumbbell handle in a cradle. The dumbbell handle is selectively connected to a selected weight plate of a plurality of weight plates. An unselected weight plate is secured to the cradle based on the selected weight plate. 
     This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter. 
     Additional features and advantages of embodiments of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of such embodiments. The features and advantages of such embodiments may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features will become more fully apparent from the following description and appended claims, or may be learned by the practice of such embodiments as set forth hereinafter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order to describe the manner in which the above-recited and other features of the disclosure can be obtained, a more particular description will be rendered by reference to specific implementations thereof which are illustrated in the appended drawings. For better understanding, the like elements have been designated by like reference numbers throughout the various accompanying figures. While some of the drawings may be schematic or exaggerated representations of concepts, at least some of the drawings may be drawn to scale. Understanding that the drawings depict some example implementations, the implementations will be described and explained with additional specificity and detail through the use of the accompanying drawings in which: 
         FIG.  1 - 1  through  1 - 5    are side views of an adjustable dumbbell system, according to at least one embodiment of the present disclosure; 
         FIG.  2    is a top down view of an adjustable dumbbell system, according to at least one embodiment of the present disclosure; 
         FIG.  3    is a representation of a cradle, according to at least one embodiment of the present disclosure; 
         FIG.  4    is a representation of a weight plate, according to at least one embodiment of the present disclosure; 
         FIG.  5 - 1    is a representation of an adjustable dumbbell system, according to at least one embodiment of the present disclosure; 
         FIG.  5 - 2    is a perspective view of a retention mechanism, according to at least one embodiment of the present disclosure; 
         FIG.  6    is a cross-sectional view of a representation of a plate adjustment mechanism, according to at least one embodiment of the present disclosure; 
         FIG.  7    is a cross-sectional view of a representation of a retention mechanism, according to at least one embodiment of the present disclosure; 
         FIG.  8    is a cross-sectional view of representation of another retention mechanism, according to at least one embodiment of the present disclosure; 
         FIG.  9    is a cross-sectional view of a representation of yet another retention mechanism, according to at least one embodiment of the present disclosure; 
         FIG.  10    is a representation of a method for securing a dumbbell, according to at least one embodiment of the present disclosure; 
         FIG.  11 - 1    through  FIG.  11 - 4    are representations of an adjustable dumbbell assembly, according to at least one embodiment of the present disclosure; 
         FIG.  12    is a representation of an adjustable dumbbell system, according to at least one embodiment of the present disclosure; and 
         FIG.  13    is a representation of a method for using an adjustable dumbbell system, according to at least one embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Adjustable dumbbells allow a user to exercise using a selected weight within a weight range, while reducing the need for individual dumbbells of a series of weights within the same weight range. Adjustable dumbbells include a handle or other support bar which may then have one or more weight plates selectively connected to the support bar. To increase the weight of the adjustable dumbbell, the user simply connects or attaches additional weight plates to the handle until the desired weight is reached. In some embodiments, the adjustable dumbbell may be a hand weight. An example of an adjustable dumbbell is shown in U.S. Pat. No. 9,795,822, the entirety of which is herein incorporated by reference. For example, the handle may be sized such that a spacing between two sets of weight plates is wide enough for a single hand. In some embodiments, the adjustable dumbbell may be a long bar, such as a bar used for squats, bench press, and so forth. The long bar may have a width between sets of weight plates sufficient for widely spaced hands (e.g., greater than shoulder length apart). In some embodiments, the adjustable dumbbell may be a weight for a weight machine. In some embodiments, the adjustable dumbbell may have a single set of weight plates, such as for a kettle ball. 
     In some embodiments, an adjustable dumbbell may include a plate adjustment mechanism that connects selected weight plates to the adjustable dumbbell until the desired weight is reached. Regardless of how the selected weight plates are connected to the handle, a user may not always have all the weight plates simultaneously connected to the handle. Therefore, when the user removes the handle from the cradle, one or more unselected weight plates may remain behind in the cradle. These unselected weight plates may become dislodged from the cradle. In at least one embodiment, an unselected weight plate that is dislodged from the cradle may become a safety hazard, and may be dropped on a user, left on the floor to be tripped over, or present another safety hazard. Furthermore, in at least one embodiment, the unselected weight plate that is dislodged from the cradle may become misplaced. For example, the unselected weight plate may be stolen, lost, put away in the wrong plate, or otherwise misplaced. 
     To prevent the unselected weight plates from becoming dislodged from the cradle, the cradle may include a retention mechanism. The retention mechanism may secure the unselected weight plates to the cradle while allowing the selected weight plates to be removed from the cradle while attached to the handle. In this manner, the unselected weight plates may not become dislodged, and therefore may not be a safety hazard or misplaced. Securing the unselected weight plates to the cradle may further improve the exercise experience for the user by removing the need for the user to consciously keep track of the unselected weight plates. 
       FIG.  1 - 1    is a side-view representation of an adjustable dumbbell system  100 , according to at least one embodiment of the present disclosure. The adjustable dumbbell system  100  includes a handle  102  and a plurality of weight plates  104 . The weight plates  104  may be selectively secured to the handle  102 . The weight plates  104  and the handle  102  are placed in a cradle  106 . The weight plates  104  include a notch  108 . A latch  110  inserted into the notch  108  may selectively secure the weight plates  104  to the cradle  106 . In this manner, when the handle  102  is removed, the weight plates that are secured to the cradle  106  may remain in the cradle  106 , and the weight plates connected to the handle  102  may become removed from the handle  102  with the cradle. 
       FIG.  1 - 2    is a representation of the adjustable dumbbell system  100  of  FIG.  1 - 1    with the handle  102  removed from the cradle  106 . In the position shown, a plurality of selected weight plates  104 - 1  are attached or connected to the handle  102 . Thus, when the handle  102  is removed from the cradle  106 , the selected weight plates  104 - 1  are removed from the cradle  106  with the handle  102 . Thus, by selecting the selected weight plates  104 - 1 , the user may customize the amount of weight attached to the handle  102 . 
     The unselected weight plates  104 - 2  remain in the cradle  106  when the handle  102  and the selected weight plates  104 - 1  are removed from the cradle  106 . The unselected weight plates  104 - 2  are secured to the cradle  106  with a latch  110  inserted into a notch  108 . By securing the unselected weight plates  104 - 2  to the cradle  106 , the unselected weight plates  104 - 2  may not become dislodged from the cradle, and may therefore have a reduced chance of becoming misplaced or a safety hazard. 
     As may be seen, only the unselected weight plates  104 - 2  are secured to the cradle  106 . Furthermore, the unselected weight plates  104 - 2  are secured to the cradle  106  before the handle  102  is removed with the selected weight plates  104 - 1 . Thus, the unselected weight plates  104 - 2  are individually and selectively secured to the cradle  106 , and the unselected weight plates  104 - 2  are individually and selectively not secured to the cradle  106 . 
       FIG.  1 - 3    and  FIG.  1 - 4    are further side-views of the adjustable dumbbell system  100  of  FIG.  1 - 1   . In the embodiment shown, the outer-most weight plate  104 - 2  is an unselected weight plate  104 - 2 , and the handle  102  is placed in the cradle  106 . The latch  110  is inserted into the notch  108  of the unselected weight plate  104 - 2 . In  FIG.  1 - 4   , the handle  102  and the connected selected weight plates  104 - 1  have been removed from the cradle  106 . The unselected weight plates  104 - 2  remain secured to the cradle  106 . 
       FIG.  1 - 5    is a top-down view of the of the adjustable dumbbell system  100  of  FIG.  1 - 1   . In the embodiment shown, the cradle  106  includes a plurality of latches  110 . Indeed, the cradle  106  includes a latch  110  for each weight plate (collectively  104 ). In the embodiment shown, each weight plate  104  includes a latch  110  on either side of the weight plate  104 . Including a latch  110  on either side of the weight plate  104  may provide a stronger connection between the weight plate  104  and the cradle  106 . 
     The cradle  106  includes a weight selection input  112 . To operate the adjustable dumbbell system  100 , the user simply inputs the desired weight into the weight selection input, and a plate adjustment mechanism (not shown) connects the selected weight plates  104 - 1  to the handle  102  and a retention mechanism secures the unselected weight plate  104 - 2  to the cradle  106 . 
     The weight selection input  112  may be any type of input. In some embodiments, the weight selection input  112  may be a manual input. For example, the weight selection input  112  may include one or more buttons. The buttons may be representative of one or more total weights of the dumbbell when the weight plates  104  are connected to the handle  102 . For example, a weight selection button may be 20 pounds, and the adjustable dumbbell system  100  may connect the appropriate number of weight plates  104  to the handle  102  to generate a total dumbbell weight of 20 pounds. In some embodiments, the adjustable dumbbell system  100  may connect an equal number of weights to either side of the handle  102 , to ensure that the dumbbell is balanced. In some embodiments, the weight selection input  112  may include a plurality of weight selection buttons, which may correspond to each available combination of weight plates  104 . In this manner, the user may simply select the desired weight, and the adjustable dumbbell system  100  may automatically connect the appropriate combination of weight plates  104  to reach the selected weight. 
     In some embodiments, the weight selection input  112  may allow the user to select the combination of specific weight plates  104 . For example, the weight selection input  112  may include a plurality of buttons each associated with a single weight plate  104 . When a button is depressed, the associated weight plates  104  may be connected to the handle  102 . This may provide the user with control over the selection and combination of individual weight plates  104  connected to the handle  102 . 
     In some embodiments, the weight selection input  112  may include one or more physical buttons that depress into the cradle or otherwise physically move when depressed. In some embodiments, the weight selection input  112  may include one or more touch-sensitive buttons. For example, the weight selection input  112  may include a touch-screen. In some embodiments, the touch-screen may include other exercise information, such as the current selected weight, the number of sets performed at the selected weight, calories burned, the current exercise, and so forth. 
     In some embodiments, the adjustable dumbbell system  100  may include a communication device. The communication device may be in communication with an external computing device. The external computing device may communicate exercise information to the adjustable dumbbell system  100 . For example, the external computing device may communicate a set weight to the adjustable dumbbell system  100 . The adjustable dumbbell system  100  may then connect the appropriate weight plates  104  to the handle  102  to reach the set weight. In some embodiments, the external computing device may communicate which weight plates  104  to connect to the handle  102  to reach the set weight. 
     In some embodiments, the external computing device may include an exercise program. The exercise program may include one or more exercises, such as curls, presses, and so forth, to be performed using the adjustable dumbbell system  100 . The exercises may include an associated exercise weight. When it is time to perform a specific exercise, the external computing device may provide the adjustable dumbbell system  100  with the exercise weight. The adjustable dumbbell system  100  may then attach the appropriate weight plates  104  to the handle  102  so that the dumbbell is set to the exercise weight. 
     In some embodiments, the adjustable dumbbell system  100  may include one or more sensors to determine when the handle  102  is connected to the cradle  106 . The communication device may communicate the presence of the handle  102  in the cradle  106  to the external computing device. In some embodiments, the external computing device may track whether the handle  102  is connected to the cradle  106 . 
     In some embodiments, the external computing device may change the exercise weight based on input from the user. For example, the user may set the exercise weight on the external computing device and the external computing device may then communicate that exercise weight to the adjustable dumbbell system  100 , which may attach the appropriate weight plates  104  to the handle  102 . In some embodiments, the external computing device may communicate the exercise weight to the adjustable dumbbell system  100  when the handle  102  is determined to be in the cradle  106 . In some embodiments, the external computing device may communicate the exercise weight to the adjustable dumbbell system  100  when the handle  102  is not connected to the cradle  106 . The adjustable dumbbell system  100  may then set the dumbbell to the exercise weight when the handle  102  is attached to the cradle  106 . 
     In some embodiments, an exercise program may include a sequential list of exercises to be performed in order. In some embodiments, the exercises may include different exercise weights. When performing the exercise program, the adjustable dumbbell system  100  may set the dumbbell to the first exercise weight by connecting the weight plates  104  to the handle  102  to set the dumbbell to the exercise weight. In some embodiments, when the handle  102  is removed from the cradle, the adjustable dumbbell system  100  and/or the external computing device may determine that the first exercise is being performed. When the handle  102  is returned to the cradle  106 , the adjustable dumbbell system  100  and/or the external computing device may advance to the next exercise by setting the adjustable dumbbell system  100  to the next exercise weight. 
     In some embodiments, the external computing device may communicate the entire exercise program to the adjustable dumbbell system  100 , and the adjustable dumbbell system  100  may execute the exercise program. In some embodiments, the external computing device may be in communication with the adjustable dumbbell system  100 , and the external computing device may provide instructions to the adjustable dumbbell system  100  for each exercise in the exercise program. 
     In some embodiments, the weight selection input  112  may include any other type of user input. For example, the weight selection input  112  may include voice-activated controls. For example, the weight selection input  112  may include a microphone and voice recognition software. The voice recognition software may be optimized to receive specific, weight-related commands. For example, in some embodiments, a user may say “set the dumbbell to 20 pounds.” The weight selection input  112  may receive the words through the microphone and process the words using the voice recognition software. The weight selection input  112  may then set the dumbbell to the appropriate weight, in this example, 20 pounds. In some embodiments, the input words may include any amount of weight. In some embodiments, the input words may include “set the dumbbell to the maximum weight,” and the adjustable dumbbell system  100  may connect all of the weight plates  104  to the handle  102 . In some embodiments, the input words may include any words that the voice recognition software may identify as a set weight. 
     In some embodiments, the weight selection input  112  may receive the input while the handle  102  of the adjustable dumbbell  100  is removed from the cradle  106 . After the handle  102  of the adjustable dumbbell  100  is replaced in the cradle  106 , the adjustable dumbbell system  100  may use the previously-received weight selection input  112  to set the adjustable dumbbell  100  to the appropriate weight. In this manner, there may be a time-delay between receiving the weight selection input  112  and setting the adjustable dumbbell  100  to the appropriate weight. In some embodiments, the adjustable dumbbell system  100  may store the received weight selection input  112  in memory after the weight selection input  112  is received and while the handle is removed from the cradle. In some embodiments, the adjustable dumbbell system  100  may prepare the adjustment to the weight of the adjustable dumbbell  100 , such as by releasing one or more weight plates  104  in the cradle  106 . In some embodiments, the adjustable dumbbell system  100  may adjust the weight of the adjustable dumbbell  100  based on a weight selection input  112  received while the handle  102  is removed from the cradle  106  without receiving any additional input. As discussed herein, the weight selection input  112  may be received in any manner, including as a voice command, a button input, received from a remote computing device, any other manner, and combinations thereof. 
     In some embodiments, the user may “queue” multiple weight selection inputs  112 . For example, the user may input weight selection inputs  112  for the next 2, 3, 4, 5, 6, 7, 8, 9, 10, or more exercise activities. The adjustable dumbbell system  100  may store the queue of weight selection inputs  112  and change the connected weight of the adjustable dumbbell to the next queued input as the handle is removed and replaced in the cradle. 
     In some embodiments, the cradle  106  of the adjustable dumbbell system  100  may include one or more state sensors for the handle  102  of the adjustable dumbbell  100 . In some embodiments, the state sensors may determine whether the handle  102  is located in the cradle  106  or whether the handle  102  is removed from the cradle  106 . In some embodiments, the state sensors may determine how many weight plates  104  are connected to the handle  102  (e.g., the connected weight of the handle). In some embodiments, the state sensors may determine how many weight plates  104  are retained in the cradle  106  when the handle  102  is removed. When the adjustable dumbbell system  100  receives a weight selection input  112 , the adjustable dumbbell system  100  may determine, using the state sensors, the state of the handle  102 . If the handle  102  is determined to not be in the cradle  106 , then the adjustable dumbbell system  100  may wait to adjust the weight of the adjustable dumbbell system  100  until the handle  102  is placed in the cradle  106  (e.g., until the state sensors determine that the state of the handle is placed in the cradle). 
     Receiving the weight selection input  112  while the handle is removed from the cradle, and setting the adjustable to the set weight after the handle is replaced in the cradle may improve the ease of use and efficiency of use of the adjustable dumbbell system. For example, a user may verbally say “my next set is at 20 lbs.” while performing a set at 15 lbs., and the adjustable dumbbell system may recognize the input and adjust the weight of the adjustable dumbbell after the user replaces the handle in the cradle. This may allow the user to focus on rest during a rest period, or on a different activity between using the adjustable dumbbells. This may reduce undesired downtime between exercise activities spent waiting for the adjustable dumbbell system to adjust the weight. In some embodiments, the user may be performing an exercise program with multiple exercise activities, and the adjustable dumbbell system  100  may receive weight selection inputs  112  associated with the exercise program when the handle is removed from the cradle, such as from a remote computing device. As discussed herein, this may reduce undesired downtime between exercise activities caused by inputting weight selection inputs  112  and waiting for the adjustable dumbbell system to make the adjustment. 
     As discussed above, each weight plate  104  may be secured to the cradle  106  individually before the handle  102  is removed from the cradle  106 . Thus, each latch of the plurality of latches  110  is individually actuated. In this manner, the unselected weight plates  104 - 2  may be secured to the cradle  106  even if the selected weight plates  104 - 1  bump and jostle the unselected weight plates  104 - 2  while being removed. 
       FIG.  2    is a representation of an adjustable dumbbell system  200 , according to at least one embodiment of the present disclosure. In the embodiment shown, the cradle includes a plurality of first latches  210 - 1  and a second latch  210 - 2 . The plurality of first latches  210 - 1  may individually actuate to secure one or more of the weight plates  204  to the cradle  206 . The second latch  210 - 2  may actuate to secure all of the weight plates  204  to the cradle  206 . This may allow a user to input into the weight selection input  212  the selected weight, and remove the handle  202  and the selected weights. When done using the adjustable dumbbell system  200 , the user may input a weight of 0, or indicate a locking input, and the second latch  210 - 2  engages with each weight plate  204  to secure all of the weight plates  204  to the cradle. This may increase the stability and/or security of the adjustable dumbbell system  200  while not in use or during transport. Furthermore, this may help to prevent some or all of the adjustable dumbbell system  200  from becoming a safety hazard. 
       FIG.  3    is a representation of an embodiment of a cradle  306 , according to at least one embodiment of the present disclosure. The cradle  306  includes a plurality of weight plate receptacles  314 . Each weight plate receptacle is configured to receive a weight plate (e.g., weight plate  104  of  FIG.  1 - 1   ). The weight plate receptacle shown is an indentation in the cradle  306 , which aligns and helps to orient the weight plates with respect to the cradle  306 . A latch (collectively  310 ) is shown in or at the edge of each weight plate receptacle  314 . The latch  310  is configured to secure a weight plate to the cradle  306  in the weight plate receptacle  314 . 
     In the embodiment shown, a first plurality of latches  310 - 1  is located on a first side of the weight plate receptacles  314 , and a second plurality of latches  310 - 2  is located on a second side of the weight plate receptacles  314 . Including latches  310  on either side of the weight plate receptacles  314  may allow for a simplified retention mechanism, or allow for the retention mechanisms to have increased control over which weight plates are selected and unselected. 
       FIG.  4    is a cut-away view of a weight plate  404  and a retention mechanism  416 , according to at least one embodiment of the present disclosure. The weight plate  404  includes a handle space  418  in a top surface  420  into which a handle (e.g., the handle  102  of  FIG.  1 - 1   ) may be inserted. The weight plate  404  further includes a notch  408  in a lateral face (collectively  422 ). In the embodiment shown, the weight plate  404  includes a notch  408  in both a first lateral face  422 - 1  and a second lateral face  422 - 2 . 
     The notch  408  includes a notch engagement angle  424 , which is the angle measured clockwise between a notch engagement surface  426  and the second lateral face  422 . In some embodiments, the notch engagement angle  424  may be in a range having an upper value, a lower value, or upper and lower values including any of 45°, 60°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 120°, 135°, or any value therebetween. For example, the notch engagement angle  424  may be greater than 45°. In another example, the notch engagement angle  424  may be less than 135°. In yet other examples, the notch engagement angle  424  may be any value in a range between 45° and 135°. A notch engagement angle  424  that is close to 90° may provide the greatest force to secure the weight plate to the cradle. In some embodiments, a notch engagement angle  424  of less than 135° may be critical to provide sufficient force to secure the weight plate to the cradle. 
     A latch  410  includes a protrusion  428  that extends into the notch  408 . In the embodiment shown, the protrusion  428  has a triangular cross-sectional shape. The protrusion  428  has a latch engagement surface  430  that engages with the notch engagement surface  426 . In the embodiment shown, the notch engagement surface  430  has the same shape as the latch engagement surface. In this manner, the bearing surface between the latch engagement surface  430  and the notch engagement surface  426  is maximized. Because protrusion  428  is inserted into the notch  408 , the protrusion  428  contacts the notch at the notch engagement surface  426  when a removal force is applied to the weight plate  404 . The interference between the notch  408  and the protrusion  428  secures the weight plate  404  to the cradle. 
     The protrusion includes a latch engagement angle  432 , which is the angle measured clockwise between the latch engagement surface  430  and a line  433  parallel to the first lateral face  422 - 1 . In some embodiments, the latch engagement angle  432  may be in a range having an upper value, a lower value, or upper and lower values including any of 45°, 60°, 75°, 80°, 85°, 90°, 95° 100°, 105°, 120°, 135°, or any value therebetween. For example, the latch engagement angle  432  may be greater than 45°. In another example, the latch engagement angle  432  may be less than 135°. In yet other examples, the latch engagement angle  432  may be any value in a range between 45° and 135°. A latch engagement angle  432  that is close to 90° may provide the greatest force to secure the weight plate to the cradle. In some embodiments, a latch engagement angle  432  of between 75° and 105° may be critical to provide sufficient force to secure the weight plate to the cradle. 
     In some embodiments, the latch engagement angle  432  and the notch engagement angle  424  are supplementary. In other words, the latch engagement angle  432  and the notch engagement angle  424  add up to 180°. Supplementary latch engagement angles  432  and notch engagement angles  424  may increase the bearing surface between the latch engagement surface and the notch engagement surface. This may increase the force with which the weight plate is secured to the cradle. In some embodiments, the latch engagement angle  432  and the notch engagement angle  424  are not supplementary, and may add up to an angle that is greater than or less than 180°. 
     The latch  410  includes a latch arm  434  that extends from the protrusion  428 . In the embodiment shown, the latch arm  434  rotates about a pivot  436 . The retention mechanism  416  includes a latch cam shaft  438  including a lobe  439 . As the latch cam shaft  438  rotates, the lobe  439  pushes on a lower portion  440  of the latch arm  434 . When the lobe  439  pushes on the lower portion  440 , the latch arm  434  rotates about the pivot  436 , and an upper portion  442  of the latch arm  434  rotates (counterclockwise in the view shown) toward the notch  408 . This may insert the protrusion  428  into the notch  408 . As the latch cam shaft  438  rotates further, the lob rotates away from the lower portion  440 , and a resilient member (not shown) may urge the arm latch  434  to rotate (clockwise in the view shown) about the pivot  436 . This may cause the upper portion  442  and the protrusion  428  move away from the notch  408 , thereby un-securing the weight plate  404  from the cradle, and allowing the weight plate  404  to be removed. 
       FIG.  5 - 1    is a top-down representation of an adjustable dumbbell system  500 , according to at least one embodiment of the present disclosure. In the embodiment shown, the adjustable dumbbell system  500  includes a first dumbbell  501 - 1  and a second dumbbell  501 - 2 . To change the weight of the first dumbbell  501 - 1  and the second dumbbell  501 - 2 , the adjustable dumbbell system  500  includes a plate adjustment mechanism  544 . The plate adjustment mechanism  544  includes a plate cam shaft gear  545  connected to a plate cam shaft (not shown). A plate primary gear  546  rotates the plate cam shaft gear, which rotates the plate cam shaft to selectively select weight plates (collectively  504 ) to connect to the handle (collectively  502 - 1 ). The plate primary gear  546  is connected to a primary shaft  547 . 
     A retention mechanism  516  includes a latch cam gear  548  connected to a latch cam shaft (not shown). A latch primary gear  549  rotates the latch cam gear  548 , which rotates the latch cam shaft to selectively insert a latch  510  into a notch (not shown) of a weight plate  504 . The latch primary gear  549  is driven by the primary shaft  547 . In this manner, the plate adjustment mechanism  544  and the retention mechanism  516  are mechanically connected. In other words, the plate adjustment mechanism  544  and the retention mechanism  516  are connected through a geared connection. For example, as the primary shaft  547  rotates, the plate cam shaft may be oriented to select one or more weight plates  504  to connect to the handle  502 . The latch cam shaft may be oriented to simultaneously latch the unselected weight plates  504  to the cradle  506 . A user may select the desired weight of the first dumbbell  501 - 1  and the second dumbbell  501 - 2  with the weight selection input  512 , and the primary shaft  547  may be rotated until the desired weight is attached to the handles  502 . 
       FIG.  5 - 2    is a perspective view of the retention mechanism  516  of  FIG.  5 - 1   . A primary shaft  547  includes a plate primary gear and a latch primary gear  549 . The latch primary gear  549  rotates a latch cam gear  548  which rotates a latch cam shaft  538 . Lobes  539  on the latch cam shaft  538  may then engage a latch to secure a weight plate to the a cradle. 
       FIG.  6    is a cross-sectional view of an adjustable dumbbell  600 , according to at least one embodiment of the present disclosure. The adjustable dumbbell  600  includes a handle  602  and a weight plate hanger  650 . The weight plate hanger  650  includes two weight plate connectors  652  that are configured to attach a weight plate  604  to the weight plate hanger  650 . The weight plate connectors  652  may be inserted into weight plate supports  654  to attach the weight plate  604  to the weight plate hanger  650 . A plate protrusion  656  may protrude from the cradle  606 . In an upper position (i.e., the position shown), the plate protrusion  656  may pull the weight plate connecters  652  out of the weight plate supports  654 , thereby detaching the weight plate  604  from the weight plate hanger  650 . 
       FIG.  7    is a cross-sectional view of an adjustable dumbbell  700 , according to at least one embodiment of the present disclosure. In the embodiment shown, a latch protrusion  768  protrudes from a weight plate receptacle  714  in a cradle  706 . The latch protrusion  768  extends into a weight plate cavity  770  in the bottom surface  772  of a weight plate  704 . The latch protrusion  768  includes two latch members  774  at a top end  771  of the latch protrusion  768 . The latch members  774  are configured to be inserted into a notch  708  in the weight plate cavity  770 . In an upper position of the latch protrusion  768 , a cavity member  773  in the weight plate cavity  770  may push the latch members  774  into the notch  708  in the weight plate cavity  770 , thereby securing the weight plate  704  to the cradle  706 . In a lower position, the latch members  774  may not be removed from the notch  708 , and the weight plate  704  may not be secured to the cradle  706 . 
       FIG.  8    is a cross-sectional view of a retention mechanism  816 , according to at least one embodiment of the present disclosure. In the embodiment shown, a latch protrusion  868  extends upward from a cradle receptacle in a cradle. A weight plate  804  includes a notch  808  in a base surface  875  of the weight plate  804 . The latch protrusion  868  may move laterally (e.g. perpendicular to the base surface  875 ). In the engaged position shown, the latch protrusion  868  is inserted into the notch  808 , thereby securing the weight plate  804  to the cradle. 
     A plate protrusion  856  may extend into a weight plate cavity  870  to selectively connect the weight plate  804  to a handle (as described in reference to  FIG.  6   ). The plate protrusion  856  and the latch protrusion  868  may both be moved by the same combined cam shaft  876 . This may simplify an adjustable dumbbell system by only using a single cam shaft. 
       FIG.  9    is a cross-sectional view of an adjustable dumbbell assembly  900 , according to at least one embodiment of the present disclosure. In the embodiment shown, the weight plate  904  includes a weight plate cavity  970 . A weight plate latch  978  may extend out of the weight plate cavity  970  and through the body of the weight plate  904 . The cradle  906  includes a weight plate receptacle  914 . A cradle protrusion  980  may protrude from the weight plate receptacle  914 . In the upper position shown, the cradle protrusion may push the weight plate latch  978  laterally such that an outer end  982  of the weight plate latch  978  extends past the lateral face  922 . The outer end  982  of the weight plate latch  978  may extend into a cradle notch  984 . In this manner, the weight plate  904  may be secured to the cradle  906 . 
       FIG.  10    is a representation of a method  1086  for securing an adjustable dumbbell, according to at least one embodiment of the present disclosure. The method  1086  includes placing a dumbbell handle in a cradle at  1088 . The dumbbell handle may be selectively connected to one or more selected weight plates of a plurality of weight plates at  1090 . One or more unselected weight plates may be secured to the cradle based on which weight plates are selected to be attached to the dumbbell handle at  1092 . Securing the unselected weight plate to the cradle may include inserting a latch on the cradle into a notch in the unselected weight plate. 
       FIG.  11 - 1    is a perspective view of an adjustable dumbbell assembly  1100 , according to at least one embodiment of the present disclosure. A cradle  1106  supports a plurality of weight plates  1104  and a handle  1102 . The handle  1102  includes a plate adjustment mechanism that selectively connects the weight plates  1104  to the handle  1102 . The plate adjustment mechanism is driven by a motor underneath the cradle  1106 . 
       FIG.  11 - 2    is another perspective view of the adjustable dumbbell assembly  1100  of  FIG.  11 - 1   . A motor  1193  underneath the cradle  1106  may control the plate adjustment mechanism. The motor  1193  rotates a first gear shaft (not shown) and a second gear shaft  1194 - 2 . The first gear shaft and the second gear shaft  1194 - 2  are connected by a plate gear belt  1195 . Thus, the first gear shaft and the second gear shaft  1194 - 2  may rotate at the same speed. 
       FIG.  11 - 3    is a top-down view of the cradle  1106  of  FIG.  11 - 1   , including a plate adjustment mechanism  1144 , according to at least one embodiment of the present disclosure. The plate adjustment mechanism includes a first gear shaft  1194 - 1  and a second gear shaft  1194 - 2 . The first gear shaft  1194 - 1  and the second gear shaft  1194 - 2  are driven by the motor  1193  shown in  FIG.  11 - 2   . A first pinion gear  1196 - 1  is connected to the first gear shaft  1194 - 1  and a second pinion gear  1196 - 2  is connected to the second gear shaft  1194 - 2 . The first pinion gear  1196 - 1  drives a first rack gear  1197 - 1  on a first plate extension bar  1198 - 1  and the second pinion gear  1196 - 2  drives a second rack gear  1197 - 2  on a second plate extension bar  1198 - 2 . 
     The first plate extension bar  1198 - 1  and the second plate extension bar  1198 - 2  are extended into a series of voids in the weight plates  1104  shown in  FIG.  11 - 1   . The length of the extension of the first plate extension bar  1198 - 1  and the second plate extension bar  1198 - 2  determines the number of weight plates  1104  that are connected to the handle  1102 . In this manner, by rotating the first gear shaft  1194 - 1  and the second gear shaft  1194 - 2 , the weight plates  1104  may be selected. 
       FIG.  11 - 4    is a cross-sectional view of the adjustable dumbbell assembly  1100  of  FIG.  11 - 1   , according to at least one embodiment of the present disclosure. The adjustable dumbbell assembly  1100  includes a plate adjustment mechanism  1144  located in the handle  1102  and a retention mechanism  1116  in the cradle  1106 . The plate adjustment mechanism  1144  and the retention mechanism  1116  are driven by the same mechanism. Specifically, the first gear shaft  1194 - 1  drives the first plate extension bar  1198 - 1  and the first retention extension bar  1199 - 1 , and the second plate gear shaft  1194 - 2  drives the second plate extension bar  1198 - 2  and the second retention extension bar  1199 - 2 . Thus, the plate adjustment mechanism  1144  may be mechanically coupled with the retention mechanism  1116 . In other words, as the plate adjustment mechanism  1144  connects weight plates  1104  to the handle  1102 , the retention mechanism  1116  may secure one or more of the unselected weight plates  1104  to the cradle  1106  in conjunction with the same operation of the motor  1193 . 
     The cradle  1106  includes a retention mechanism slot  1103 . As the first gear shaft  1194 - 1  rotates, a first retention pinion gear (not shown) on the first gear shaft  1194 - 1  may engage with a first retention rack gear on the first retention extension bar  1199 - 1 . This may cause the first retention extension bar  1199 - 1  to extend into the retention mechanism slot  1103 , where it may engage one or more latches. The one or more latches may engage one or more of the unselected weight plates  1104 , thereby securing them to the cradle. Similarly, as the second gear shaft  1194 - 2  rotates, a second retention pinion gear  1105 - 2  on the second gear shaft  1194 - 2  may engage with a second retention rack gear on the second retention extension bar  1199 - 2 . This may cause the second retention extension bar  1199 - 2  to extend into the retention mechanism slot  1103 , where it may engage one or more latches. The one or more latches may engage one or more of the unselected weight plates  1104 , thereby securing them to the cradle. 
     In some embodiments, each of the weight plates  1104  may be connected to each other with an interlocking connection  1107 . For example, in the embodiment shown, the interlocking connection may allow the weight plates  1104  to be separated from each other using an upward force, but may prevent separation from each other using a downward or a longitudinal force (e.g., parallel to the handle  1102 ). In some embodiments, the interlocking connection  1107  may be a dovetail connection. In some embodiments, the interlocking connection  1107  may be any type of interlocking connection. 
     The interlocking connection  1107  may help to keep all of the unselected weight plates  1104  oriented in the same orientation. In this manner, the handle  1102  and the selected weight plates  1104  may be removed from the cradle  1106 , and all of the unselected weight plates  1104  may remain upright in the cradle  1106 . This may allow the handle  1102  and the selected weight plates  1102  to be easily re-inserted into the cradle  1106  without having to align the unselected weight plates in the cradle  1106 . 
     In some embodiments, the retention mechanism  1116  may include a retention protrusion  1109  at either end of the cradle  1106 . The retention protrusions  1109  may extend into an end weight plate  1111 . The end weight plate  1111  may be connected to the other weight plates  1104  with the interlocking connection  1107 . Thus, when the handle  1102  is removed, the end weight plate  1111  may remain secured to the cradle  1106 , and the remaining unselected weight plates  1104  may remain oriented relative to the end weight plate  1111  via the interlocking connection  1107 . Thus, the end weight plates  1111  may be the only weight plate secured to the cradle  1106 , and the remaining weight plates  1104  may remain upright based on the interlocking connection  1107  to the end weight plate  1111 . 
     In some embodiments, the retention protrusions  1109  may be rigidly attached to the cradle  1106 . For example, the retention protrusions  1109  may have a height and/or position relative to the cradle  1106  that does not change based on an actuation of the plate adjustment mechanism  1144 . In some embodiments, the retention protrusions  1109  may be actuated. For example, the retention protrusions  1109  may have an adjustable height, and may only extend into the end weight plate  1111  when the retention mechanism  1116  activates the retention protrusion  1109 . In other examples, the end weight plate  1111  may be secured to the cradle  1106  using a latch on the lateral face of the end weight plate  1111 , or any other mechanism described herein. 
       FIG.  12    is a schematic representation of an adjustable dumbbell control system  1223 , according to at least one embodiment of the present disclosure. The adjustable dumbbell control system  1223  may be used to control the any of the adjustable dumbbells and associated hardware discussed herein. For example, the adjustable dumbbell control system  1223  may be used to control the adjustable dumbbell system  100  of  FIG.  1   , the adjustable dumbbell system  200  of  FIG.  2   , the cradle  306  of  FIG.  3   , the retention mechanism  416  of  FIG.  4   , the adjustable dumbbell system  500  of  FIG.  5 - 1    and  FIG.  5 - 2   , the adjustable dumbbell  600  of  FIG.  6   , the adjustable dumbbell  700  of  FIG.  7   , the retention mechanism of  816  of  FIG.  8   , the adjustable dumbbell assembly  900  of  FIG.  9   , the adjustable dumbbell assembly  1100  of  FIG.  11 - 1    through  FIG.  11 - 4   , and combinations thereof. The adjustable dumbbell control system  1223  may be used to execute the method  1086  of  FIG.  10   . 
     The adjustable dumbbell control system  1223  includes an adjustable dumbbell system  1200 . The adjustable dumbbell system  1200  may include a weight controller  1213 . The weight controller  1213  may be configured to attach weight plates to a handle based on a set weight. The weight controller  1213  may receive the set weight from the weight selection input  1215 . A user may input a set weight into the weight selection input  1215 , and, based on the set weight set entered into the weight selection input, the weight controller  1213  may attach an appropriate number of plates to the handle to set the adjustable dumbbell to the set weight. In this manner, by using the weight selection input  1215 , the user may have an increased control over his or her workouts. This may improve the exercise experience. 
     In accordance with embodiments of the present disclosure, the weight controller  1213  may connect weight plates to the handle using any structure, mechanism, actuator, or other device discussed herein. For example, the weight controller  1213  may activate one or more latches to secure the selected weight plates to the handle. In some examples, the weight controller  1213  may activate one or more latches to secure unselected weight plates to the cradle. In some embodiments, based on the set weight, the weight controller  1213  may identify a combination of weight plates to attach to the handle. the weight controller  1213  may then connect the identified combination of weight plates to the handle using any mechanism discussed herein. In some embodiments, the weight controller  1213  may connect unselected or identified weight plates to the cradle to reduce the risk of loss or injury from a loose weight plate. 
     In some embodiments, the weight selection input  1215  may receive the set weight using any type of input. For example, the user may enter the set weight into the weight selection input  1215  with a verbal command. For example, the user may verbalize a command, such as “set the weight to 15 pounds.” A microphone on a voice recognition input  1217  may receive the verbal command, and voice recognition software may process the verbal command to determine the set weight. After processing the verbal command, the voice recognition input  1217  may communicate the set weight to the weight controller  1213 . 
     In some embodiments, the weight selection input  1215  may receive the set weight from a remote computing device  1219 . The remote computing device  1219  may transmit the set weight to a communication device at the weight selection input  1215 , which may then send the set weight to the weight controller  1213 . The weight controller  1213  may then attach the appropriate weight plates to the handle to arrive at the set weight. 
     In some embodiments, the weight selection input  1215  may receive the set weight from one or more buttons  1221  on a cradle or otherwise connected to the adjustable dumbbell system  1200 . The buttons  1221  may include specific set weights, specific weight plates to connect to the handle, weight increments, activities associated with set weights, any other button input, and combinations thereof. 
     In some embodiments, the adjustable dumbbell system  1200  may further include a display  1225 . The display  1225  may include exercise information associated with the adjustable dumbbell. For example, the display  1225  may provide the user with information regarding the set weight, the weight plates attached to the handle, an exercise to be performed, a previous and/or pending exercise, set weights to associated with one or more exercises, an exercise timer, a rest timer, a calorie burn value, any other exercise information, and combinations thereof. 
     In some embodiments, the display  1225  may include one or more elements of the weight selection input  1215 . For example, the display  1225  may include one or more buttons  1221 . In some embodiments, the display  1225  may be a touch-sensitive display, and the buttons  1221  may be a designated portion of the touch-sensitive display. In some embodiments, the display  1225  may provide instructions to the user to provide verbal commands to the adjustable display system  1200 . In some embodiments, the display  1225  may provide information received from the remote computing device  1217 . 
     In some embodiments, the weight selection input may receive the input while the handle of the adjustable dumbbell is removed from the cradle. After the handle of the adjustable dumbbell is replaced in the cradle, the adjustable dumbbell system may use the previously-received weight selection input to set the adjustable dumbbell to the appropriate weight. In this manner, there may be a time-delay between receiving the weight selection input and setting the adjustable dumbbell to the appropriate weight. In some embodiments, the adjustable dumbbell system may store the received weight selection input in memory after the weight selection input is received and while the handle is removed from the cradle. In some embodiments, the adjustable dumbbell system may prepare the adjustment to the weight of the adjustable dumbbell, such as by releasing one or more weight plates in the cradle. In some embodiments, the adjustable dumbbell system may adjust the weight of the adjustable dumbbell based on a weight selection input received while the handle is removed from the cradle without receiving any additional input. As discussed herein, the weight selection input may be received in any manner, including as a voice command, a button input, received from a remote computing device, any other manner, and combinations thereof. 
     In some embodiments, the user may “queue” multiple weight selection inputs. For example, the user may input weight selection inputs for the next 2, 3, 4, 5, 6, 7, 8, 9, 10, or more exercise activities. The adjustable dumbbell system  100  may store the queue of weight selection inputs and change the connected weight of the adjustable dumbbell to the next queued input as the handle is removed and replaced in the cradle. 
     In some embodiments, the cradle of the adjustable dumbbell system may include one or more state sensors for the handle of the adjustable dumbbell. In some embodiments, the state sensors may determine whether the handle is located in the cradle or whether the handle is removed from the cradle. In some embodiments, the state sensors may determine how many weight plates are connected to the handle (e.g., the connected weight of the handle). In some embodiments, the state sensors may determine how many weight plates are retained in the cradle when the handle is removed. When the adjustable dumbbell system receives a weight selection input, the adjustable dumbbell system may determine, using the state sensors, the state of the handle. If the handle is determined to not be in the cradle, then the adjustable dumbbell system may wait to adjust the weight of the adjustable dumbbell system until the handle is placed in the cradle (e.g., until the state sensors determine that the state of the handle is placed in the cradle). 
     Receiving the weight selection input while the handle is removed from the cradle, and setting the adjustable to the set weight after the handle is replaced in the cradle may improve the ease of use and efficiency of use of the adjustable dumbbell system. For example, a user may verbally say “my next set is at 20 lbs.” while performing a set at 15 lbs., and the adjustable dumbbell system may recognize the input and adjust the weight of the adjustable dumbbell after the user replaces the handle in the cradle. This may allow the user to focus on rest during a rest period, or on a different activity between using the adjustable dumbbells. This may reduce undesired downtime between exercise activities spent waiting for the adjustable dumbbell system to adjust the weight. In some embodiments, the user may be performing an exercise program with multiple exercise activities, and the adjustable dumbbell system may receive weight selection inputs associated with the exercise program when the handle is removed from the cradle, such as from a remote computing device. As discussed herein, this may reduce undesired downtime between exercise activities caused by inputting weight selection inputs and waiting for the adjustable dumbbell system to make the adjustment. 
       FIG.  13    is a representation of a method  1327  for securing an adjustable dumbbell, according to at least one embodiment of the present disclosure. The method  1327  may be performed by the adjustable dumbbell control system  1223  of  FIG.  12   . 
     In accordance with embodiments of the present disclosure, the method  1327  may include receiving a set weight from a weight selection input at  1329 . For example, the weight selection input may include a voice recognition input, and the set weight may be input using a verbal command from a user. In some examples, the set weight may be input using a button, may be received from a remote computing device, or may be input using any other input mechanism. 
     Based on the received/inputted set weight, one or more weight plates may be selectively connected to a handle to set the adjustable dumbbell to the set weight at  1331 . In some embodiments, a weight controller may identify which weight plates to connect to the handle to reach the set weight, and may provide instructions to the adjustment mechanism to connect the weight plates to the handle. Any unselected weight plates may be connected to the cradle at  1335 . An unselected weight plate may be a weight plate that is not connected to the handle. In some embodiments, the weight controller may identify the unselected weight plates. 
     INDUSTRIAL APPLICABILITY 
     Adjustable dumbbells allow a user to exercise using a selected weight within a weight range, while reducing the need for individual dumbbells of a series of weights within the same weight range. Adjustable dumbbells include a handle or other support bar which may then have one or more weight plates selectively connected to the support bar. To increase the weight of the adjustable dumbbell, the user simply connects or attaches additional weight plates to the handle until the desired weight is reached. In some embodiments, the adjustable dumbbell may be a hand weight. For example, the handle may be sized such that a spacing between two sets of weight plates is wide enough for a single hand. In some embodiments, the adjustable dumbbell may be a long bar, such as a bar used for squats, bench press, and so forth. The long bar may have a width between sets of weight plates sufficient for widely spaced hands (e.g., greater than shoulder length apart). In some embodiments, the adjustable dumbbell may be a weight for a weight machine. In some embodiments, the adjustable dumbbell may have a single set of weight plates, such as for a kettle ball. 
     In some embodiments, an adjustable dumbbell may include a plate adjustment mechanism that connects selected weight plates to the adjustable dumbbell until the desired weight is reached. Regardless of how the selected weight plates are connected to the handle, a user may not always have all the weight plates simultaneously connected to the handle. Therefore, when the user removes the handle from the cradle, one or more unselected weight plates may remain behind in the cradle. These unselected weight plates may become dislodged from the cradle. In at least one embodiment, an unselected weight plate that is dislodged from the cradle may become a safety hazard, and may be dropped on a user, left on the floor to be tripped over, or present another safety hazard. Furthermore, in at least one embodiment, the unselected weight plate that is dislodged from the cradle may become misplaced. For example, the unselected weight plate may be stolen, lost, put away in the wrong plate, or otherwise misplaced. 
     To prevent the unselected weight plates from becoming dislodged from the cradle, the cradle may include a retention mechanism. The retention mechanism may secure the unselected weight plates to the cradle while allowing the selected weight plates to be removed from the cradle while attached to the handle. In this manner, the unselected weight plates may not become dislodged, and therefore may not be a safety hazard or misplaced. Securing the unselected weight plates to the cradle may further improve the exercise experience for the user by removing the need for the user to consciously keep track of the unselected weight plates. 
     The plate adjustment mechanism may be located anywhere in an adjustable dumbbell system. In some embodiments, the plate adjustment mechanism may be located in the handle of the adjustable dumbbell. A dial or gear on an outer edge of the adjustable dumbbell may rotate a shaft through the handle that includes a plurality of plate adjustment cams. The plate adjustment cams may selectively insert a pin into a notch in weight plate, thereby selecting the weight plate to be attached or connected to the handle. 
     In some embodiments, the adjustable dumbbell may be placed in a cradle, and the plate adjustment mechanism may be located in the cradle. The plate adjustment mechanism may include a protrusion in the cradle that extends into a cavity in a weight plate. The protrusion may have an adjustable height. In an upper position, the protrusion may push a latch on a support member connected to the handle inward, away from a notch in the cavity of the weight plate. This will decouple the weight plate from the handle. In a lower position, the protrusion may not contact the latch, and the latch may be urged into the notch in the cavity of the weight plate by a resilient member. 
     The cradle may include a retention mechanism including one or more latches. Each latch may be located on the cradle and selectively inserted into a notch on a weight plate. By inserting the latch into the notch, the retention mechanism may secure an unselected weight plate to the cradle. In some embodiments, each weight plate may be associated with a latch. The retention mechanism may selectively secure the latch to an associated weight plate while the adjustable dumbbell is placed in the cradle. In this manner, unselected weight plates may be secured to the cradle before the adjustable dumbbell with the selected weight plates attached to the handle is removed from the cradle. In at least one embodiment, securing the unselected weight plates to the cradle before the adjustable dumbbell is removed may help the unselected weight plates from becoming dislodged from the cradle when the adjustable dumbbell is removed. For example, the unselected weight plates may be secured to the cradle despite bumping, jostling, or friction forces on the unselected weight plates by the handle and/or the selected weight plates during removal of the handle and selected weight plates. 
     In some embodiments, an adjustable dumbbell may include multiple weight plates on two ends of a handle. In this manner, a user may grip the handle and move the weights while holding the handle. In some embodiments, an equal weight may be attached to the handle on either end. In some embodiments, an unequal weight may be attached to the handle. In other words, a first end of the handle may have more weight secured to it than a second end of the handle. This may occur because more weight plates are attached to the first end of the handle. In some embodiments, the retention mechanism may secure more unselected weight plates to the second end of the cradle than the first end of the cradle to match the unbalanced adjustable dumbbell. 
     In some embodiments, the retention mechanism may include a single latch that secures multiple weight plates to the cradle. For example, the single latch may include a bar that extends an entirety of the length of the adjustable dumbbell. In some examples, the single latch may secure some, but not all, of the weight plates to the cradle. In some embodiments, the single latch may secure two, three, four, five, six, or more weight plates to the cradle. In some embodiments, a single adjustable dumbbell may include both individual latches for each weight plate and a long, bar latch that may secure multiple weight plates to the cradle. This may increase the stability of the connection between the weight plates and the cradle, and may prevent misplacement of the weight plates and prevent the weight plates from becoming safety hazards. 
     In some embodiments, the weight plates are shaped like a plate. The plate has a length, a width, and a depth. In some embodiments, the length and the width may be approximately the same, such as with a square, a circle, or other equilateral polygon. In some embodiments, the length and the width may be different, such as with a rectangle, an ellipse, or other polygonal or non-polygonal structure. The length and width may be larger than the depth of the weight plate. Thus, the weight plate may represent a plate, a disc, or other planar structure. The depth may be the smallest dimension between any two faces of the weight plate. 
     The weight plates may include two base faces and at least one outer face that runs along an outer circumference of the weight plate. In some embodiments, the depth may be the smallest measurement between two edges of the outer face. The base faces may have any cross-sectional shape, including circular, elliptical, square, rectangular, triangular, pentagonal, hexagonal, polygonal of any side, non-polygonal, or other cross-sectional shape. The outer face may include one or more faces, depending on the number of edges of the cross-sectional shape. For example, the outer face may include an upper face, a base face opposite the upper face, and first and second lateral faces transverse to the upper face and the base face, the first lateral face being opposite the second lateral face. 
     Each weight plate includes a notch. The notch may be located at any location on the weight plate. In some embodiments, the notch may be located on a first base face or a second base face. In some embodiments, the notch may be located on the outer face, such as on the first lateral face, the second lateral face, both the first lateral face and the second lateral face, the top face, the cradle face, and combinations thereof. In some embodiments, the notch is an indentation, cavity, or void in the face of the weight plate. In some embodiments, the notch may be located inside a cavity in the weight plate. 
     The notch may have any number of edges, including 1, 2, 3, 4, 5, 6, or more sides. The edges of the notch may have any shape, including a curved edge, a straight edge, or a combination of curved and straight edges. Thus, the notch may have any shape, including hemispherical, cylindrical, triangular, square, rectangular, pentagonal, hexagonal, or any other shape. 
     In some embodiments, the latch of the retention mechanism includes a protrusion that extends into the notch. In some embodiments, the protrusion may be triangular, pyramidal, hemispherical, cylindrical, conical, or any other shape that may be inserted into the notch. 
     In some embodiments, a latch engagement surface of the latch has a complementary shape to a notch engagement surface of the notch. For example, the latch engagement surface may be flat and at a latch engagement angle. The notch engagement surface may similarly be flat and have a notch engagement angle. When activated, the notch may engage the notch at the notch engagement surface, and a majority or all of the latch engagement surface may be in contact with a majority or all of the notch engagement surface. This may increase the bearing area, which may help to increase the resistance to dislodging and/or removal of the unselected weight plates. 
     In some embodiments, the latch engagement angle, as measured counterclockwise relative to the lateral face, may be in a range having an upper value, a lower value, or upper and lower values including any of 45°, 60°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 120°, 135°, or any value therebetween. For example, the latch engagement angle may be greater than 45°. In another example, the latch engagement angle may be less than 135°. In yet other examples, the latch engagement angle may be any value in a range between 45° and 135°. A latch engagement angle that is close to 90° may provide the greatest force to secure the weight plate to the cradle. In some embodiments, a latch engagement angle of greater than 45° may be critical to provide sufficient force to secure the weight plate to the cradle. 
     In some embodiments, the notch engagement angle, as measured counterclockwise relative to the lateral face, may be in a range having an upper value, a lower value, or upper and lower values including any of 45°, 60°, 75°, 80°, 85°, 90°, 95°, 100°, 105°, 120°, 135°, or any value therebetween. For example, the notch engagement angle may be greater than 45°. In another example, the notch engagement angle may be less than 135°. In yet other examples, the notch engagement angle may be any value in a range between 45° and 135°. A notch engagement angle that is close to 90° may provide the greatest force to secure the weight plate to the cradle. In some embodiments, a notch engagement angle of less than 135° may be critical to provide sufficient force to secure the weight plate to the cradle. 
     In some embodiments, the latch engagement angle and the notch engagement angle are supplementary. In other words, the latch engagement angle and the notch engagement angle add up to 180°. Supplementary latch engagement angles and notch engagement angles may increase the bearing surface between the latch engagement surface and the notch engagement surface. This may increase the force with which the weight plate is secured to the cradle. In some embodiments, the latch engagement angle and the notch engagement angle are not supplementary, and may add up to an angle that is greater than or less than 180°. 
     In some embodiments, the latch has a complementary cross-sectional shape with the notch. Thus, when actuated, the latch may be inserted into the notch and provide resistance to removal of the unselected weight plate from the cradle. In some embodiments, the latch has a non-complementary cross-sectional shape with the notch. 
     In some embodiments, the latch may be located to a side of the adjustable dumbbell. In this manner, the latch may be configured connect to a notch that is on a lateral face or the top face of the weight plates. In some embodiments, a latch to the side of the adjustable dumbbell may engage the top face directly, and not a notch in the top face, to secure the weight plate to the cradle. This may allow the retention system to secure the weight plate to the cradle. Furthermore, retention system to the side of the adjustable dumbbell may allow the user to visibly verify that the latch is engaged with the weight plate. 
     In some embodiments, the latch may be located underneath the adjustable dumbbell. In this manner, the latch may be configured to be inserted into a cavity in the cradle surface of the weight plate and engage a notch located in the cavity. This may allow the weight plate to be secured to the cradle, and may prevent a user from tampering with the retention mechanism. 
     In some embodiments, the retention mechanism in the cradle may exert a force on the latch, thereby inserting the latch into and out of the notch. For example, the retention mechanism may include a retention cam shaft including a plurality of lobes. The lobes may be spaced longitudinally along the retention shaft and aligned with a latch arm on the latch. As a lobe pushes on the latch arm, the protrusion on the latch may be moved relative to the notch. Each latch may include a resilient member that urges the latch opposite the direction the lobe pushes on the latch arm (e.g., toward or away from the notch). The resilient member may include a coil spring, a torsion spring, a wave spring, a resilient foam, an elastically deformable material, any other resilient member, and combinations of the foregoing. 
     In some embodiments, when the lobe on the retention cam shaft pushes on the latch arm, the protrusion may be moved into the notch. In some embodiments, when the lobe on the retention cam shaft pushes on the latch arm, the protrusion may be moved away from the notch. In some embodiments, the latch arm may include a pivot. When the lobe on the retention cam shaft pushes on the latch arm, the latch arm may rotate around a pivot. Thus, when the retention cam shaft is on the dumbbell side of the latch, when the lobe pushes on the latch arm, the protrusion may be moved into the notch. When the retention cam shaft is opposite the dumbbell across the latch, when the lobe pushes on the latch arm, the protrusion may be moved away from the notch. 
     In some embodiments, the latch may translate (e.g., not rotate, move laterally toward/away from) with respect to the weight plate. Thus, when the retention cam shaft is on the dumbbell side of the latch, when the lobe pushes on the latch, the protrusion may be moved away from the notch. When the retention cam shaft is opposite the dumbbell across the latch, when the lobe pushes on the latch, the protrusion is moved toward the notch. 
     In some embodiments, the latch may be located underneath the cradle surface of the weight plate. When the adjustable dumbbell is placed on the cradle, the latch may protrude into a cavity in the cradle surface of the weight plate. The latch may include two rotating latch members. In a latch upper position, a cavity member in the cavity may push the rotating latch members into a notch in the cavity, thereby securing the weight plate to the cradle. In a latch lower position, the rotating latch members may not contact the cavity member, and the rotating latch members will not be inserted into the notch, thereby allowing the weight plate to be removed from the cradle. In some embodiments, a retention cam shaft may be located underneath the latch. A lobe on the retention cam shaft may push the latch into the upper position. 
     In some embodiments, the weight plate may include a base face notch in the notch of a base face. The latch may extend upward into a cavity in the weight plate. The latch may move laterally (e.g., perpendicularly toward and away from the base face notch) until the latch is engaged with the base face notch. In this manner, the latch may move horizontally to secure the weight plate to the cradle. 
     In some embodiments, a retention mechanism may move the latch toward or away from the notch, and may include any retention mechanism, including a cam shaft, a solenoid, a linear motor, a piezoelectric material, other linear motion devices, and combinations of the foregoing. In some embodiments, the retention mechanism may include lobes located on the cam shaft selectively and individually engage or actuate the latches. In some embodiments, the cam shaft may actuate a single latch at a time. In some embodiments, the cam shaft may actuate more than one latch at a time. In some embodiments, the cam shaft may actuate all the latches at once. In some embodiments, the cam shaft may include multiple lobes on the same circumference, which may actuate a latch at different rotational positions. In this manner, the cam shaft may actuate different combinations of latches depending on the combination of selected and unselected weight plates. In some embodiments, a plurality of latches may use the same cam shaft. In some embodiments, all the latches may use the same cam shaft. In some embodiments, multiple cam shafts may actuate multiple latches. In some embodiments, each latch may be located on the same side of the weight plates. In some embodiments, at least one latch may be located on a first side of the weight plates, and at least one latch may be located on a second side of the weight plates. 
     In some embodiments, as discussed above, the weight plates may be selected and attached to the handle using a plate protrusion extending from a plate receptacle into a cavity in the weight plate. Furthermore, as discussed above, the latch may protrude from the plate receptacle. Thus, each weight plate may have two protrusions extending into the weight plate. In some embodiments, the plate protrusion and the latch may extend into the same cavity in the weight plate. In some embodiments, the plate protrusion and the latch may extend into different cavities in the weight plate. In some embodiments, the plate protrusion and the latch may be actuated by the same retention mechanism. For example, the plate protrusion and the latch may be actuated using the same cam shaft, with the lobes on the cam shaft being configured to actuate both the plate protrusion and the latch. In some embodiments, the plate protrusion and the latch may be actuated by different retention mechanisms. For example, the plate protrusion may be actuated by a plate cam shaft and the latch may be actuated by a latch cam shaft. 
     In some embodiments, the weight plate may include plate latch, and the cradle may include a cradle notch. A protrusion may extend up from a plate receptacle and into a cavity in the weight plate. In an upper position, the protrusion may push one or more plate latches laterally outward. The one or more plate latches may extend into the cradle notch. Thus, when the adjustable dumbbell is removed, the unselected weight plate may be secured to the cradle with the plate latch inserted into the cradle notch. In some embodiments, a retention mechanism may be located underneath the latch and move the latch between the upper and lower position. In some embodiments, the weight plate may include both a plate latch and a notch, and the cradle may include a latch and a cradle notch. This may provide additional strength to the contact between the weight plate and the cradle, thereby providing additional protection from dislodging the weight plate from the cradle. 
     In some embodiments, each latch of the plurality of latches may have an associated retention mechanism. This may allow for many different combinations of engaged latches, and therefore many different combinations of weight plates that are secured to the cradle. This may increase the versatility of the adjustable dumbbell, which may improve the user experience. In some embodiments, multiple latches may use the same retention mechanism. This may simplify the cradle assembly, which may improve reliability and decrease manufacturing costs. 
     In some embodiments, the plate adjustment mechanism may be mechanically connected to the retention mechanism. In this manner, as the selected weight plates are connected to the handle or the bar support, the unselected weight plates may be automatically secured to the cradle. For example, an adjustable dumbbell may include at least two weight plates. A user may select a desired weight for the adjustable dumbbell with a weight selection input on the cradle, the dumbbell, the handle, or other location. The user may cause the plate adjustment mechanism to select a first weight and connect it to the handle. Using the plate adjustment mechanism may mechanically activate the retention mechanism, which may secure the unselected weight plate to the cradle. In at least one embodiment, mechanically connecting the plate adjustment mechanism to the retention mechanism may simplify the use of the adjustable dumbbell by allowing the user to focus on selecting and using the desired weight plates, without worrying about securing the unselected weight plates or worrying about safety hazards from unselected weight plates. 
     In some embodiments, the plate adjustment mechanism may include a combined cam shaft to connect weight plates to the handle, and retention mechanism use the same combined cam shaft to engage the latches in the notches of the weight plates, thereby securing the weight plates to the handle. In some embodiments, the plate adjustment mechanism may include a plate cam shaft in the handle of the adjustable dumbbell. The plate cam shaft may be rotated by a plate gear on a primary shaft. A latch cam shaft may selectively engage the latches with the weight plates. The latch cam shaft may be rotated by a latch gear. In some embodiments, the latch gear may be on the same primary shaft as the plate gear. In some embodiments, the latch gear may be located on a secondary shaft that is connected to the primary shaft with a geared connection. Furthermore, this may help to prevent mistakenly securing unselected weight plates to the cradle. Still further, this may help to prevent mistakenly failing to secure an unselected weight plate, which may then become misplaced or become a safety hazard. 
     In some embodiments, the cradle may include weight plate receptacles, a plate adjustment mechanism, and a retention mechanism sufficient to operate single adjustable dumbbell. In some embodiments, the cradle may include weight plate receptacles, plate adjustment mechanisms, and retention mechanisms sufficient to operate single adjustable dumbbell. In some embodiments, plate adjustment mechanism and the retentions mechanism for multiple adjustable dumbbells may be operated by the same driving force, such as a primary shaft. This may simplify the dumbbell adjustment process for the user. Furthermore, this may help to prevent mistakenly securing unselected weight plates to the cradle. Still further, this may help to prevent mistakenly failing to secure an unselected weight plate, which may then become misplaced or become a safety hazard. 
     In some embodiments, a method for securing an adjustable dumbbell includes placing a dumbbell handle in a cradle. The dumbbell handle may be selectively connected to one or more selected weight plates of a plurality of weight plates. One or more unselected weight plates may be secured to the cradle based on which weight plates are selected to be attached to the dumbbell handle. Securing the unselected weight plate to the cradle may include inserting a latch on the cradle into a notch in the unselected weight plate. Securing the unselected weight plates to the cradle may further include inserting a protrusion into a cavity in the unselected weight plate, the protrusion including a latch that connects to a notch in the cavity. 
     The method may further include selecting the selected weight plate and identifying the unselected weight plate as any weight plate of the plurality of weight plates that is not the selected weight plate. In other words, the total number of weight plates may be divided into selected weight plates connected or attached to the dumbbell handle, and unselected weight plates secured to the cradle. 
     In some embodiments, the weight selection input may receive the input while the handle of the adjustable dumbbell is removed from the cradle. After the handle of the adjustable dumbbell is replaced in the cradle, the adjustable dumbbell system may use the previously-received weight selection input to set the adjustable dumbbell to the appropriate weight. In this manner, there may be a time-delay between receiving the weight selection input and setting the adjustable dumbbell to the appropriate weight. In some embodiments, the adjustable dumbbell system may store the received weight selection input in memory after the weight selection input is received and while the handle is removed from the cradle. In some embodiments, the adjustable dumbbell system may prepare the adjustment to the weight of the adjustable dumbbell, such as by releasing one or more weight plates in the cradle. In some embodiments, the adjustable dumbbell system may adjust the weight of the adjustable dumbbell based on a weight selection input received while the handle is removed from the cradle without receiving any additional input. As discussed herein, the weight selection input may be received in any manner, including as a voice command, a button input, received from a remote computing device, any other manner, and combinations thereof. 
     In some embodiments, the user may “queue” multiple weight selection inputs. For example, the user may input weight selection inputs for the next 2, 3, 4, 5, 6, 7, 8, 9, 10, or more exercise activities. The adjustable dumbbell system  100  may store the queue of weight selection inputs and change the connected weight of the adjustable dumbbell to the next queued input as the handle is removed and replaced in the cradle. 
     In some embodiments, the cradle of the adjustable dumbbell system may include one or more state sensors for the handle of the adjustable dumbbell. In some embodiments, the state sensors may determine whether the handle is located in the cradle or whether the handle is removed from the cradle. In some embodiments, the state sensors may determine how many weight plates are connected to the handle (e.g., the connected weight of the handle). In some embodiments, the state sensors may determine how many weight plates are retained in the cradle when the handle is removed. When the adjustable dumbbell system receives a weight selection input, the adjustable dumbbell system may determine, using the state sensors, the state of the handle. If the handle is determined to not be in the cradle, then the adjustable dumbbell system may wait to adjust the weight of the adjustable dumbbell system until the handle is placed in the cradle (e.g., until the state sensors determine that the state of the handle is placed in the cradle). 
     Receiving the weight selection input while the handle is removed from the cradle, and setting the adjustable to the set weight after the handle is replaced in the cradle may improve the ease of use and efficiency of use of the adjustable dumbbell system. For example, a user may verbally say “my next set is at 20 lbs.” while performing a set at 15 lbs., and the adjustable dumbbell system may recognize the input and adjust the weight of the adjustable dumbbell after the user replaces the handle in the cradle. This may allow the user to focus on rest during a rest period, or on a different activity between using the adjustable dumbbells. This may reduce undesired downtime between exercise activities spent waiting for the adjustable dumbbell system to adjust the weight. In some embodiments, the user may be performing an exercise program with multiple exercise activities, and the adjustable dumbbell system may receive weight selection inputs associated with the exercise program when the handle is removed from the cradle, such as from a remote computing device. As discussed herein, this may reduce undesired downtime between exercise activities caused by inputting weight selection inputs and waiting for the adjustable dumbbell system to make the adjustment. 
     In some embodiments, an adjustable dumbbell may include a rack and pinion plate adjustment mechanism. A motor may be located in the cradle and a shaft may extend through the cradle and connect to a gear housing. The gear housing may include a pinion gear. The handle may be hollow and include an extension arm. A rack gear (e.g., a linear gear) may be located inside the hollow handle. The rack gear may be connected to the pinion gear. As the pinion gear rotates, the rack gear may extend the extension arm. Each weight plate may include a void through which the extension arm may extend. The length of extension of the extension arm may determine the number of selected weight plates, and therefore the total weight, of the adjustable dumbbell. The motor may also be connected to a retention mechanism including a rack and pinion gear in the cradle, which may extend a latch arm. The latch arm may cause latches to engage/disengage with notches on the weight plates corresponding to the selected and unselected weight plates. Thus, the plate adjustment mechanism and the retention mechanism may be connected through a geared connection. 
     In some embodiments, a cradle supports a plurality of weight plates and a handle. The handle includes a plate adjustment mechanism that selectively connects the weight plates to the handle. The plate adjustment mechanism is driven by a motor underneath the cradle. 
     A motor underneath the cradle may control the plate adjustment mechanism. The motor rotates a first gear shaft and a second gear shaft. The first gear shaft and the second gear shaft are connected by a plate gear belt. Thus, the first gear shaft and the second gear shaft may rotate at the same speed. 
     The plate adjustment mechanism includes a first gear shaft and a second gear shaft. The first gear shaft and the second gear shaft are driven by the motor. A first pinion gear is connected to the first gear shaft and a second pinion gear is connected to the second gear shaft. The first pinion gear drives a first rack gear on a first plate extension bar and the second pinion gear drives a second rack gear on a second plate extension bar. 
     The first plate extension bar and the second plate extension bar are extended into a series of voids in the weight plates. The length of the extension of the first plate extension bar and the second plate extension bar determines the number of weight plates that are connected to the handle. In this manner, by rotating the first gear shaft and the second gear shaft, the weight plates may be selected. 
     The adjustable dumbbell assembly includes a plate adjustment mechanism located in the handle and a retention mechanism in the cradle. The plate adjustment mechanism and the retention mechanism are driven by the same mechanism. Specifically, the first gear shaft drives the first plate extension bar and the first retention extension bar, and the second plate gear shaft drives the second plate extension bar and the second retention extension bar. Thus, the plate adjustment mechanism may be mechanically coupled with the retention mechanism. In other words, as the plate adjustment mechanism connects weight plates to the handle, the retention mechanism may secure one or more of the unselected weight plates to the cradle in conjunction with the same operation of the motor. 
     The cradle includes a retention mechanism slot. As the first gear shaft rotates, a first retention pinion gear (not shown) on the first gear shaft may engage with a first retention rack gear on the first retention extension bar. This may cause the first retention extension bar to extend into the retention mechanism slot, where it may engage one or more latches. The one or more latches may engage one or more of the unselected weight plates, thereby securing them to the cradle. Similarly, as the second gear shaft rotates, a second retention pinion gear on the second gear shaft may engage with a second retention rack gear on the second retention extension bar. This may cause the second retention extension bar to extend into the retention mechanism slot, where it may engage one or more latches. The one or more latches may engage one or more of the unselected weight plates, thereby securing them to the cradle. 
     In some embodiments, each of the weight plates may be connected to each other with an interlocking connection. For example, in the embodiment shown, the interlocking connection may allow the weight plates to be separated from each other using an upward force, but may prevent separation from each other using a downward or a longitudinal force (e.g., parallel to the handle). In some embodiments, the interlocking connection may be a dovetail connection. In some embodiments, the interlocking connection may be any type of interlocking connection. 
     The interlocking connection may help to keep all of the unselected weight plates oriented in the same orientation. In this manner, the handle and the selected weight plates may be removed from the cradle, and all of the unselected weight plates may remain upright in the cradle. This may allow the handle and the selected weight plates to be easily re-inserted into the cradle without having to align the unselected weight plates in the cradle. 
     In some embodiments, the retention mechanism may include a retention protrusion at either end of the cradle. The retention protrusions may extend into an end weight plate. The end weight plate may be connected to the other weight plates with the interlocking connection. Thus, when the handle is removed, the end weight plate may remain secured to the cradle, and the remaining unselected weight plates may remain oriented relative to the end weight plate via the interlocking connection. Thus, the end weight plates may be the only weight plate secured to the cradle, and the remaining weight plates may remain upright based on the interlocking connection to the end weight plate. 
     In some embodiments, the retention protrusions may be rigidly attached to the cradle. For example, the retention protrusions may have a height and/or position relative to the cradle that does not change based on an actuation of the plate adjustment mechanism. In some embodiments, the retention protrusions may be actuated. For example, the retention protrusions may have an adjustable height, and may only extend into the end weight plate when the retention mechanism activates the retention protrusion. In other examples, the end weight plate may be secured to the cradle using a latch on the lateral face of the end weight plate, or any other mechanism described herein. 
     Below are sections of the current disclosure: 
     A1. A system for securing an adjustable dumbbell, comprising:
         a handle;   a plate adjustment mechanism configured to selectively connect a selected weight plate of a plurality of weight plates to the handle, each weight plate of the plurality of weight plates including an engagement surface;   a cradle configured to receive the plurality of weight plates, the cradle including a latch; and   a retention mechanism configured to selectively engage the latch with the engagement surface of an unselected weight plate of the plurality of weight plates, wherein the plate adjustment mechanism is mechanically connected to the retention mechanism.
 
A2. The system of section A1, wherein the plate adjustment mechanism is located in the cradle.
 
A3. The system of section A1 or section A2, wherein the retention mechanism inserts a protrusion on the latch into a notch having the engagement surface.
 
A4. The system of any of section A1 through A3, wherein the plate adjustment mechanism is connected to the retention mechanism with a geared connection.
 
A5. The system of section A4, wherein the plate adjustment mechanism includes a plate cam shaft and the retention mechanism includes a latch cam shaft, and wherein the plate cam shaft and the latch cam shaft are driven by a primary shaft.
 
A6. The system of any of sections A1 through A5, wherein the retention mechanism includes a motor configured to move the latch in and out of engagement with the engagement surface.
 
A7. The system of section A6, wherein the motor is controlled by an exercise program.
 
A8. The system of section A6 or A7, wherein an exercise controller actuates the retention mechanism based on user input.
 
A9. The system of section A8, wherein the user input is received at a computing device.
 
A10. The system of section A9, wherein the user input includes a voice command received by a voice recognition module.
 
A11. The system of section A9 or A10, wherein the user input includes an input in one or more buttons.
 
A12. The system of any of sections A7 through A11, wherein the exercise program is received or controlled by a remote computing device.
 
A13. The system of any of sections A7 through A12, wherein a selected weight is displayed on the display.
 
A14. The system of any of sections A1 through A13, wherein the retention mechanism includes a plurality of latches configured to be selectively inserted into the engagement surface.
 
A15. The system of section A14, wherein the cradle includes a plurality of weight plate receptacle, and each weight plate receptacle includes a latch of the plurality of latches.
 
A16. The system of section A15, further comprising a plurality of protrusions extending from the weight plate receptacles, and wherein each weight plate of the plurality of weight plates includes a cavity, a protrusion from the plurality of protrusions extending into the cavity.
 
A17. The system of section A16, wherein each protrusion of the plurality of protrusions includes a latch of the plurality of latches, and wherein the cavity includes the notch.
 
A18. The system of any of sections A14 through section A17, wherein the notch is located on an outer face of each weight plate of the plurality of weight plates.
 
A19. The system of section A18, wherein the notch is located on a lateral face of each weight plate of the plurality of weight plates.
 
A20. The system of section A19, wherein the notch is a first notch, and each weight plate of the plurality of weight plates includes a second notch.
 
A21. The system of section A20, wherein each weight plate of the plurality of weight plates is secured to the cradle with a first latch of the plurality of latches inserted into the first notch and a second latch of the plurality of latches inserted into the second notch.
 
A22. The system of any of sections A19 through A21, wherein a single latch is inserted into the notch of two weight plates of the plurality of weight plates.
 
A23. The system of section A22, wherein the single latch includes a bar that extends along a length of the handle.
 
A24. The system of any of sections A18 through A23, wherein the notch is located on a top face of at least one weight plate of the plurality of weight plates.
 
B1. A system for securing an adjustable dumbbell, comprising:
   a handle;   a plurality of weight plates removably connected to the handle, each weight plate of the plurality of weight plates including a notch; and   a cradle including:
           a plurality of weight plate receptacles configured to receive each weight plate of the plurality of weight plates; and   a plurality of latches configured to be selectively inserted into the notch located on each weight plate of the plurality of weight plates, wherein the plurality of latches are individually actuated.
 
B2. The system of section B1, wherein each weight plate receptacle includes a latch of the plurality of latches.
 
B3. The system of section B2, further comprising a plurality of protrusions extending from the weight plate receptacles, and wherein each weight plate of the plurality of weight plates includes a cavity, a protrusion from the plurality of protrusions extending into the cavity.
 
B4. The system of section B3, wherein each protrusion of the plurality of protrusions includes a latch of the plurality of latches, and wherein the cavity includes the notch.
 
B5. The system of any of sections B1 through section B4, wherein the notch is located on an outer face of each weight plate of the plurality of weight plates.
 
B6. The system of section B5, wherein the notch is located on a lateral face of each weight plate of the plurality of weight plates.
 
B7. The system of section B6, wherein the notch is a first notch, and each weight plate of the plurality of weight plates includes a second notch.
 
B8. The system of section B7, wherein each weight plate of the plurality of weight plates is secured to the cradle with a first latch of the plurality of latches inserted into the first notch and a second latch of the plurality of latches inserted into the second notch.
 
B9. The system of any of sections B6 through B8, wherein a single latch is inserted into the notch of two weight plates of the plurality of weight plates.
 
B10. The system of section B9, wherein the single latch includes a bar that extends along a length of the handle.
 
B11. The system of any of sections B5 through B10, wherein the notch is located on a top face of at least one weight plate of the plurality of weight plates.
 
B12. The system of any of sections B1 through B11, wherein the cradle includes a motor configured to move the plurality of latches in and out of engagement with the notch on the plurality of weight plates.
 
B13. The system of section B12, wherein the motor is controlled by an exercise program.
 
B14. The system of section B12 or B13, wherein an exercise controller actuates the retention mechanism based on user input.
 
B15. The system of section B14, wherein the user input is received at a computing device.
 
B16. The system of section B15, wherein the user input includes a voice command received by a voice recognition module.
 
B17. The system of section B15 or B16, wherein the user input includes an input in one or more buttons.
 
B18. The system of any of sections B13 through B17, wherein the exercise program is received or controlled by a remote computing device.
 
B19. The system of any of sections B13 through B18, wherein a selected weight is displayed on the display.
 
B20. The system of any of sections B13 through B19, wherein the retention mechanism includes a plurality of latches configured to be selectively inserted into the engagement surface.
 
C1. A method for securing an adjustable dumbbell, comprising:
   
           placing a dumbbell handle in a cradle;   selectively connecting the dumbbell handle to a selected weight plate of a plurality of weight plates; and   securing an unselected weight plate of the plurality of weight plates to the cradle based on the selected weight plate connected to the dumbbell handle.
 
C2. The method of section C1, further comprising:
   selecting the selected weight plate; and   identifying the unselected weight plate as any weight plate of the plurality of weight plates that is not the selected weight plate.
 
C3. The method of section C1 or section C2, wherein securing the unselected weight plate includes inserting a latch into a notch in the unselected weight plate.
 
C4. The method of any of sections C1 through C3, wherein securing the unselected weight plate includes inserting a weight plate latch on the weight plate into a cradle notch on the cradle.
 
C5. The system of any of sections C1 through C4, wherein selectively connecting the dumbbell handle to the selected weight plate includes actuating a retention mechanism with a motor.
 
C6. The system of section C5, further comprising controlling the motor with an exercise program.
 
C7. The system of section C5 or C6, further comprising actuating the retention mechanism based on user input.
 
C8. The system of section C7, further comprising receiving the user input at a computing device.
 
C9. The system of section C8, wherein the user input includes a voice command received by a voice recognition module.
 
C10. The system of section C8 or C9, wherein the user input includes an input in one or more buttons.
 
C11. The system of any of sections C8 through C10, wherein the exercise program is received or controlled by a remote computing device.
 
C12. The system of any of sections C6 through C11, wherein a selected weight is displayed on the display.
 
C13. The system of any of sections C6 through C12, wherein the retention mechanism includes a plurality of latches configured to be selectively inserted into the engagement surface.
 
D1. A method for securing an adjustable dumbbell, comprising:
   a. receiving a set weight from a weight selection input while a handle of the adjustable dumbbell is removed from a cradle, the cradle supporting a plurality of weight plate selectively connectable to the handle;   b. when the handle is placed in the cradle, selectively connecting one or more selected weight plates of the plurality of weight plates to the handle to set the adjustable dumbbell to the set weight; and   c. securing an unselected weight plate of the plurality of weight plates to a cradle based on the selected weight plate connected to the handle.
 
D2. The method of section D1, wherein the weight selection input is a voice recognition input, and wherein receiving the set weight from the weight selection input includes receiving a verbal command at the voice recognition input.
 
D3. The method of section D1 or D2, wherein receiving the set weight includes receiving the set weight from a remote computing device.
 
D4. The method of any of sections D1-D3, further comprising determining that the handle is located in the cradle when the handle is placed in the cradle.
 
D5. The method of any of sections D1-D4, wherein, when the handle is removed from the cradle, the handle includes one or more connected weight plates, and wherein selectively connecting the one or more selected weight plates includes disconnecting one or more of the connected weight plates.
 
D6. The method of any of sections D1-D5, further comprising storing the set weight while the handle is removed from the cradle.
 
D7. The method of section D6, wherein storing the set weight includes storing the set weight until the handle is placed in the cradle.
 
D8. The method of any of sections D1-D7, further comprising:
   a. selecting the selected weight plate; and   b. identifying the unselected weight plate as any weight plate of the plurality of weight plates that is not the selected weight plate.
 
D9. The method of any of sections D1-D8, wherein securing the unselected weight plate includes inserting a latch into a notch in the unselected weight plate.
 
D10. The method of any of sections D1-D9, wherein securing the unselected weight plate includes inserting a weight plate latch on the
       

     One or more specific embodiments of the present disclosure are described herein. These described embodiments are examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, not all features of an actual embodiment may be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous embodiment-specific decisions will be made to achieve the developers&#39; specific goals, such as compliance with system-related and business-related constraints, which may vary from one embodiment to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. 
     The articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements in the preceding descriptions. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. For example, any element described in relation to an embodiment herein may be combinable with any element of any other embodiment described herein. Numbers, percentages, ratios, or other values stated herein are intended to include that value, and also other values that are “about” or “approximately” the stated value, as would be appreciated by one of ordinary skill in the art encompassed by embodiments of the present disclosure. A stated value should therefore be interpreted broadly enough to encompass values that are at least close enough to the stated value to perform a desired function or achieve a desired result. The stated values include at least the variation to be expected in a suitable manufacturing or production process, and may include values that are within 5%, within 1%, within 0.1%, or within 0.01% of a stated value. 
     A person having ordinary skill in the art should realize in view of the present disclosure that equivalent constructions do not depart from the spirit and scope of the present disclosure, and that various changes, substitutions, and alterations may be made to embodiments disclosed herein without departing from the spirit and scope of the present disclosure. Equivalent constructions, including functional “means-plus-function” clauses are intended to cover the structures described herein as performing the recited function, including both structural equivalents that operate in the same manner, and equivalent structures that provide the same function. It is the express intention of the applicant not to invoke means-plus-function or other functional claiming for any claim except for those in which the words ‘means for’ appear together with an associated function. Each addition, deletion, and modification to the embodiments that falls within the meaning and scope of the claims is to be embraced by the claims. 
     The terms “approximately,” “about,” and “substantially” as used herein represent an amount close to the stated amount that still performs a desired function or achieves a desired result. For example, the terms “approximately,” “about,” and “substantially” may refer to an amount that is within less than 5% of, within less than 1% of, within less than 0.1% of, and within less than 0.01% of a stated amount. Further, it should be understood that any directions or reference frames in the preceding description are merely relative directions or movements. For example, any references to “up” and “down” or “above” or “below” are merely descriptive of the relative position or movement of the related elements. 
     The present disclosure may be embodied in other specific forms without departing from its spirit or characteristics. The described embodiments are to be considered as illustrative and not restrictive. The scope of the disclosure is, therefore, indicated by the appended claims rather than by the foregoing description. Changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.