Patent Publication Number: US-7214168-B2

Title: Variable path exercise apparatus

Description:
PRIORITY CLAIM 
     This application claims the benefits of U.S. Provisional Patent Application No. 60/476,548 entitled “Variable Stride Elliptic Exercise Device” to Robert E. Rodgers, Jr., filed on Jun. 6, 2003; U.S. Provisional Patent Application No. 60/486,333 entitled “Variable Stride Exercise Device” to Robert E. Rodgers, Jr., filed on Jul. 11, 2003; U.S. Provisional Patent Application No. 60/490,154 entitled “Variable Stride Exercise Device” to Robert E. Rodgers, Jr., filed on Jul. 25, 2003; U.S. Provisional Patent Application No. 60/491,382 entitled “Variable Stride Exercise Device” to Robert E. Rodgers, Jr., filed on Jul. 31, 2003; U.S. Provisional Patent Application No. 60/494,308 entitled “Variable Stride Exercise Device” to Robert E. Rodgers, Jr., filed on Aug. 11, 2003; U.S. Provisional Patent Application No. 60/503,905 entitled “Variable Stride Exercise Device” to Robert E. Rodgers, Jr., filed on Sep. 19, 2003; U.S. Provisional Patent Application No. 60/511,190 entitled “Variable Stride Apparatus” to Robert E. Rodgers, Jr., filed on Oct. 14, 2003; and U.S. Provisional Patent Application No. 60/515,238 entitled “Variable Stride Exercise Device” to Robert E. Rodgers, Jr., filed on Oct. 29, 2003. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to an exercise apparatus. Certain embodiments relate to variable motion exercise apparatus that may allow exercise such as simulated climbing, walking, striding, and/or jogging. 
     2. Description of Related Art 
     Exercise devices have been in use for years. Some typical exercise devices that simulate walking or jogging include cross country ski machines, elliptical motion machines, and pendulum motion machines. 
     Elliptical motion exercise apparatus in many cases provide inertia that assists in direction change of the pedals, making the exercise smooth and comfortable (e.g., see U.S. Pat. No. 5,242,343 to Miller; U.S. Pat. No. 5,383,829 to Miller; U.S. Pat. No. 5,518,473 to Miller; U.S. Pat. No. 5,755,642 to Miller; U.S. Pat. No. 5,577,985 to Miller; U.S. Pat. No. 5,611,756 to Miller; U.S. Pat. No. 5,911,649 to Miller; U.S. Pat. No. 6,045,487 to Miller; U.S. Pat. No. 6,398,695 to Miller; U.S. Pat. No. 5,913,751 to Eschenbach; U.S. Pat. No. 5,916,064 to Eschenbach; U.S. Pat. No. 5,921,894 to Eschenbach; U.S. Pat. No. 5,993,359 to Eschenbach; U.S. Pat. No. 6,024,676 to Eschenbach; U.S. Pat. No. 6,042,512 to Eschenbach; U.S. Pat. No. 6,045,488 to Eschenbach; U.S. Pat. No. 6,077,196 to Eschenbach; U.S. Pat. No. 6,077,198 to Eschenbach; U.S. Pat. No. 6,090,013 to Eschenbach; U.S. Pat. No. 6,090,014 to Eschenbach; U.S. Pat. No. 6,142,915 to Eschenbach; U.S. Pat. No. 6,168,552 to Eschenbach; U.S. Pat. No. 6,210,305 to Eschenbach; U.S. Pat. No. 6,361,476 to Eschenbach; U.S. Pat. No. 6,409,632 to Eschenbach; U.S. Pat. No. 6,422,976 to Eschenbach; U.S. Pat. No. 6,422,977 to Eschenbach; U.S. Pat. No. 6,436,007 to Eschenbach; U.S. Pat. No. 6,440,042 to Eschenbach; U.S. Pat. No. 6,482,132 to Eschenbach; and U.S. Pat. No. 6,612,969 to Eschenbach). 
     Elliptical motion exercise apparatus are also described in U.S. Pat. No. 5,573,480 to Rodgers, Jr.; U.S. Pat. No. 5,683,333 to Rodgers, Jr.; U.S. Pat. No. 5,738,614 to Rodgers, Jr.; U.S. Pat. No. 5,924,962 to Rodgers, Jr.; U.S. Pat. No. 5,938,567 to Rodgers, Jr.; U.S. Pat. No. 5,549,526 to Rodgers, Jr.; U.S. Pat. No. 5,593,371 to Rodgers, Jr.; U.S. Pat. No. 5,595,553 to Rodgers, Jr.; U.S. Pat. No. 5,637,058 to Rodgers, Jr.; U.S. Pat. No. 5,772,558 to Rodgers, Jr.; U.S. Pat. No. 5,540,637 to Rodgers, Jr.; U.S. Pat. No. 5,593,372 to Rodgers, Jr.; U.S. Pat. No. 5,766,113 to Rodgers, Jr.; and U.S. Pat. No. 5,813,949 to Rodgers, Jr.; U.S. Pat. No. 5,690,589 to Rodgers, Jr.; U.S. Pat. No. 5,743,834 to Rodgers, Jr.; U.S. Pat. No. 5,611,758 to Rodgers, Jr.; U.S. Pat. No. 5,653,662 to Rodgers, Jr.; and U.S. Pat. No. 5,989,163 to Rodgers, Jr., each of which is incorporated by reference as if fully set forth herein. 
     In many exercise apparatus, rigid coupling to a crank generally confines the elliptical path to a fixed stride or path length. The fixed elliptical path length may either be too long for shorter users or too short for taller users. 
     Adjustable stride elliptical exercise apparatus have been disclosed in previous patents (e.g., U.S. Pat. No. 5,743,834 to Rodgers, Jr.). Although some of these exercise apparatus have addressed the issue of a fixed path length, the stride adjustment is made through changes or adjustments to the crank geometry. Mechanisms for adjustment in such apparatus may add significant cost, may require input by a user to a control system, and/or may not react relatively quickly to user input. 
     Pivoting foot pedal systems have been disclosed in previous patents (e.g., U.S. Pat. No. 5,690,589 to Rodgers, Jr.). Pivoting foot pedal systems may be configured such that the pivotal connection to the pedal is located above the pedal surface and a pendulum action may occur during pedal pivoting. This pendulum action may slightly increase the stride length. Such increases in stride length, however, are generally a small percentage of stride length and are not generally perceived by a user of the apparatus. 
     U.S. Pat. No. 6,689,019 to Ohrt et al., which is incorporated by reference as if fully set forth herein, discloses a user defined, dynamically variable stride exercise apparatus. A crank based system with a link that engages a roller at the end of a crank is disclosed. The link may have springs or cams to control and limit stride length. The cams, however, are placed away from the user. The resultant forces created by the cam are limited because the full weight of the user may not be applied to the cam. A housing to cover the crank and cam system may be large, thus adding to manufacturing cost. In addition, the overall length of the system may be relatively high. 
     SUMMARY 
     In certain embodiments, a variable stride exercise apparatus may provide a variable range of motion controlled by a user of the apparatus. In an embodiment, an exercise apparatus may include a frame. A crank system may be coupled to the frame. A pivotal linkage assembly may be coupled to the crank system. In certain embodiments, a pivotal linkage assembly may include a foot member and/or an arm link. The foot member may include or be coupled to a footpad. In some embodiments, a movable member may be coupled to the pivotal linkage assembly or be a part of the pivotal linkage assembly. The movable member may be coupled to the crank system. In certain embodiments, the apparatus may be designed such that the foot of the user can travel in a substantially closed path during use of the apparatus. In some embodiments, the apparatus may be designed such that the foot of the user can travel in a curvilinear path during use of the apparatus. In some embodiments, the apparatus may be designed such that the foot of the user can travel in a relatively linear path during use of the apparatus. 
     In certain embodiments, a variable stride system may be coupled to the pivotal linkage assembly. In some embodiments, a variable stride system may include a cam device. In certain embodiments, a variable stride system may include a spring device and/or a damper device. A variable stride system may be coupled to a foot member and/or a movable member. In certain embodiments, the foot member may be coupled to the movable member through the variable stride system. The variable stride system may allow a user of the apparatus to vary the length of the user&#39;s stride during use of the apparatus. Varying the length of the user&#39;s stride may allow a user to selectively vary the path of the user&#39;s foot (e.g., by varying the path of the foot member or footpad). 
     In certain embodiments, an exercise apparatus has a maximum stride length that is at least about 40% of an overall length of the apparatus. In some embodiments, a variable stride system may be coupled to a foot member within about 24 inches of an end of a footpad. In certain embodiments, the variable stride system may be coupled to the foot member such that at least a portion of the variable stride system is located under at least a portion of the footpad. In some embodiments, the variable stride system may be coupled to the foot member at a location between the footpad and the crank system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description and upon reference to the accompanying drawings in which: 
         FIGS. 1A ,  1 B,  1 D,  1 E, and  1 F depict embodiments of closed paths. 
         FIG. 1C  depicts an embodiment of a curvilinear path. 
         FIGS. 2A ,  2 B,  2 C, and  2 D depict embodiments of cam type resistive/restoring devices that may provide a variable range of motion in a closed path. 
         FIGS. 3A ,  3 B,  3 C, and  3 D depict embodiments of spring and/or damper devices that may provide a variable range of motion in a closed path. 
         FIG. 4  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 4A  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 5  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 6  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 7  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 8  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 9  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 10  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 11  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 12  depicts a side view of an embodiment of an exercise apparatus without tracks or rollers. 
         FIG. 13  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 14  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 15  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 16  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 17  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 18  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 19  depicts a schematic of an embodiment of an exercise apparatus with an articulating cam device. 
         FIG. 20  depicts a schematic of an embodiment of an exercise apparatus with a dual radius crank. 
         FIG. 21  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 22  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 23  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 24  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 25  depicts a schematic of an embodiment of an exercise apparatus that uses dual cranks. 
         FIG. 26  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 27  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 28  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 29  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 30  depicts a schematic of an embodiment of an exercise apparatus with a spring/damper device. 
         FIG. 31  depicts a schematic of an embodiment of an exercise apparatus with a spring/damper device. 
         FIG. 32  depicts a schematic of an embodiment of an exercise apparatus with a spring/damper device. 
         FIG. 33  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 34  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 35  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 36  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 37  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 37A  depicts a top view of an embodiment of an exercise apparatus. 
         FIG. 38  depicts representations of possible paths of motion in an exercise apparatus. 
         FIG. 39  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 40  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 41  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 42  depicts a schematic of an embodiment of an exercise apparatus. 
         FIG. 43  depicts a schematic of an embodiment of an exercise apparatus. 
     
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and may herein be described in detail. The drawings may not be to scale. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     In the context of this patent, the term “coupled” means either a direct connection or an indirect connection (e.g., one or more intervening connections) between one or more objects or components. The phrase “directly attached” means a direct connection between objects or components. 
     Aerobic exercise apparatus may be designed to create a variable path (e.g., a closed path or a reciprocating path) in space for limb engaging devices. For example, an exercise apparatus may create an approximately elliptical or approximately circular closed path in space (e.g., as shown in  FIGS. 1A and 1B ) for foot pedals or footpads to simulate a climbing, walking, striding, or jogging motion. In some embodiments, an exercise apparatus may create an approximately curvilinear path in space (e.g., as shown in  FIG. 1C ) for foot pedals or footpads to simulate a climbing, walking, striding, or jogging motion. Footpads may move in a repetitive manner along a closed path. A closed path may be defined as a path in which an object (e.g., a user&#39;s foot, footpad, or foot member) travels in a regular or irregular path around a point or an area. The shape of a closed path may depend on the generating linkage mechanism. For example, a closed path may be an elliptical path, a saddle-shaped path, an asymmetrical path (e.g., a closed path with a smaller radius of curvature on one side of the path as compared to the other side), or an ovate or egg-shaped path. Examples of closed paths are shown in  FIGS. 1A ,  1 B,  1 D,  1 E, and  1 F. In some embodiments, a closed path may be elliptical, orbital, or oblong. In certain embodiments, footpads may move in a repetitive manner along a curvilinear path or an arcuate path. 
     Exercise apparatus that create a defined path in space may have certain advantages. Certain advantages may include, but are not limited to, the reduction or elimination of impact on a user, an integrated inertia system that automatically causes directional change of the footpads, and/or a rapid learning curve for the user. These machines may, however, limit the range of motion of the user. An exercise apparatus that provides a user with a variable range of motion may advantageously provide compactness, controllable foot articulation patterns, and/or better variable stride control suitable for a greater variety of users. 
     In certain embodiments, certain types of systems may be used to provide a variable range of motion on an exercise apparatus. A “variable stride system” may be used to provide a variable range of motion on an exercise apparatus so that a user&#39;s stride length is variable during use of the apparatus. Variable stride systems may include cam type resistive/restoring devices and/or spring/damper type resistive/restoring devices. One or more portions of a variable stride system may be coupled to or incorporated as part of an exercise apparatus. 
       FIGS. 2A–2D  depict embodiments of cam type resistive/restoring devices that may provide a variable range of motion in a closed path. In  FIG. 2A , foot member  100  with cam device  102  engages roller  104 . Foot member  100  may translate forward and rearward as surface of cam device  102  moves along roller  104 . As a user steps on foot member  100 , forces may be created by the interaction of the cam device surface and roller  104  such that the foot member is either accelerated or decelerated. In some embodiments, a slider may be used instead of roller  104  depicted in  FIG. 2A . A slider may produce frictional drag forces, which in some cases may induce desirable damping forces. 
     In  FIG. 2B , the relationship between the cam device and roller is inverted. Roller  104  is directly attached to foot member  100 . Cam device  102  is separate from foot member  100  and engages roller  104 .  FIG. 2C  depicts a variety of surface shapes that may be used for cam device  102 . The surface of cam device  102  may take on a variety of shapes depending on the objectives of a designer of an exercise apparatus. Certain profiles for cam device  102  may generate more or less restoring force. Cam device rotation during use of an exercise apparatus may affect the choice of the cam device surface shape by a designer. Portions of the cam device surface may be concave relative to the roller. In some embodiments, portions of the cam device surface may be convex relative to the roller. In some embodiments, portions of the cam device surface may also be straight and still generate restoring forces in certain configurations, as shown in  FIG. 2D . The orientation of a cam device may change as a linkage system operates. For example, there may be rotation in space relative to a fixed reference plane such as the floor. In certain embodiments, this cam device rotation in space may be referred to as “cam device rotation”. Cam device rotation during use of an exercise apparatus may cause the cam device surface to tilt relative to a roller. Restoring forces may be generated by this relative tilt to generate a desired performance of the exercise apparatus. 
       FIGS. 3A–3D  depict embodiments of spring and/or damper devices that may provide a variable range of motion in a closed path. In certain embodiments, a spring/damper device may include a spring only, a damper only, a spring and damper combination in parallel, or a spring and damper combination in series. In an embodiment of a spring/damper device using only a damper, there typically will be resistive force without any restoring force. When a foot member is displaced from its neutral position, a spring/damper device resists movement of the foot member and may assist in returning the foot member to its neutral or start position.  FIG. 3A  depicts an embodiment of foot member  100  supported on rollers  104 . Foot member  100  may translate back and forth supported by rollers  104 . Spring/damper device  106  may resist motion of foot member  100  and provide a restoring force for the foot member. In some embodiments, foot member  100  may translate through a sliding motion without the use of rollers. In some embodiments, translation features for foot member  100  may be included in a telescoping system that allows relative translation between the telescoping components. Spring/damper device  106  may be located within the telescoping components.  FIG. 3B  depicts an embodiment with two spring/damper devices  106  in combination.  FIG. 3C  depicts an embodiment with foot member  100  able to translate between two spring/damper devices  106  and engage the spring/damper devices only toward the end of the foot member&#39;s travel.  FIG. 3C  also shows that spring/damper devices  106  may be used in combination with cam device  102 .  FIG. 3D  depicts an embodiment with spring/damper devices  106  moving with foot member  100  and engaging stops to generate a resistive/restoring force. 
       FIG. 4  depicts a side view of an embodiment of an exercise apparatus. Frame  108  may include a basic supporting framework and an upper stalk. Frame  108  may be any structure that provides support for one or more components of an exercise apparatus. In certain embodiments, all or a portion of frame  108  may remain substantially stationary during use. For example, all or a portion of frame  108  may remain substantially stationary relative to a floor on which the exercise apparatus is used. “Stationary” generally means that an object (or a portion of the object) has little or no movement during use. 
     In an embodiment, rails  110  may be coupled to and/or supported by frame  108 . In some embodiments, frame  108  may perform the function of rails  110 . In  FIG. 4 , both right and left sides of the linkage system are shown. The right and left sides of the linkage system may be used for the right and left feet of a user, correspondingly. The right and left sides of the linkage system may be mirror images along a vertical plane oriented along the center of the machine as viewed from above. In other embodiments depicted herein, only the left or right side may be shown. It is to be understood that in embodiments where only one side of the linkage system is depicted, the other side may be a mirror image of the depicted side. 
     Left and right movable members  112  may be supported at the rear by wheels  114 . Wheels  114  may translate in rails  110 . In certain embodiments, left and right movable members  112  may be movable members that move in a back and forth motion (i.e., one member moves forward as the other member moves backward in a reciprocating motion). In some embodiments, movable members  112  may be movable members that move in a closed path (e.g., a circular path, an elliptical path, or an asymmetrical path). The path or motion (e.g., reciprocating motion or closed path motion) of movable members  112  may be determined during the process of designing an exercise apparatus (e.g., by a designer of the exercise apparatus). For example, a designer of an exercise apparatus may design the linkage geometry of the exercise apparatus to provided a determined path of motion of movable members  112 . The forward portions of movable members  112  may be pivotally coupled to crank members  116 . Arm links  118  may be pivotally coupled to and supported by frame  108  at point  120 . Arm links  118  may be pivotally coupled to foot members  100 . In certain embodiments, arm links  118  may be directly attached (e.g., pivotally and directly attached) to foot members  100 . Arm links  118  may be designed so that the upper portions can be used as grasping members (e.g., handles). A “pivotal linkage assembly” is generally an assembly that includes two or more moving links that are pivotally coupled to each other. In certain embodiments, a pivotal linkage assembly includes foot member  100  and arm link  118 . In some embodiments, a pivotal linkage assembly may include one or more other components such as links, connectors, and/or additional members that couple to and/or provide coupling between foot member  100  and arm link  118  (e.g., movable member  112 ). 
     Crank members  116  may drive pulley device  122 , which in turn may drive brake/inertia device  124  using belt  126 . A “crank system” may include, in a generic case, crank member  116  coupled (either directly attached or indirectly attached) to pulley device  122 . In some embodiments, a crank system may be formed from other types of devices that generally convert reciprocation or motion of a member to rotation. For example, a crank system may include a ring (e.g., a metal ring) supported by one or more rollers. In certain embodiments, a crank system may include one or more intermediate components between the crank member and the pulley (e.g., an axle or connectors). In certain embodiments, a crank system may be directly attached to frame  108 . In some embodiments, a crank system may be indirectly coupled to frame  108  with one or more components coupling the crank system to the frame. 
     Foot member  100  may have footpads  128  or any other surface on which a user may stand. Footpad  128  is typically any surface or location on which a user&#39;s foot resides during use of an exercise apparatus (e.g., the footpad may be a pad or a pedal on which the user&#39;s foot resides during use). In some embodiments, footpad  128  may be a portion of foot member  100 . Roller  104  may be coupled to foot member  100  by bracket  130 . Roller  104  may engage movable member  112  at cam device  102 . Cam device  102  may be formed to a specific shape to provide desired operating characteristics. In some embodiments, cam device  102  may be included as a part of movable member  112 . In certain embodiments, cam device  102  and roller  104 , or any other variable stride system, may be located within about 24 inches (e.g., about 18 inches or about 12 inches) of an end of footpad  128 . In certain embodiments, at least a portion of a variable stride system (e.g., a cam device) may be located under (e.g., directly under) at least a portion of footpad  128 . 
     The forward portion of movable member  112  is shown to be straight in  FIG. 4 . Movable member  112  may, however, be curved and/or include a bend. In certain embodiments, movable member  112  is made of a solid or unitary construction. In some embodiments, movable member  112  may include multiple components coupled or fastened to achieve a desired performance. Similarly, foot members  100  and arm links  118  may be straight, bent, or curved. Foot members  100  and arm links  118  may be unitary or may include multiple components. 
     In an embodiment, a user ascends the exercise apparatus, stands on footpads  128  and initiates a walking, striding, or jogging motion. The weight of the user on footpads  128  combined with motion of the footpads and foot members  100  causes a force to be transmitted to movable members  112  through roller  104  and cam device  102 . This force in turn causes the rotation of crank members  116 , pulley device  122 , and/or brake/inertia device  124 . As crank members  116  rotate, movable members  112  undertake a reciprocating motion near wheels  114 . In an embodiment, foot member  100  and movable member  112  interact through roller  104 , which is free to translate relative to movable member  112  at cam device  102 . In certain embodiments, the interaction of foot member  100  and movable member  112  at cam device  102  (or any other variable stride system) may result in changing or dynamic angular relationship. The nature of the interaction and the magnitude and direction of the forces transmitted through roller  104  may be controlled by the shape and/or orientation of cam device  102 . 
     As the user variably applies force on footpads  128 , force may be transmitted through rollers  104  to movable members  112  that drive crank members  116 . In certain embodiments, as crank members  116  rotate, the crank members may impart force to movable members  112 , which in turn may impart force to foot members  100  through roller  104  and cam device  102 , particularly at the end or beginning of a step or stride by the user. These forces may assist in changing direction of foot member  100  at the end or beginning of a step. In certain embodiments, these forces may assist in returning a user&#39;s foot to a neutral position during use. In an embodiment, the user determines and selects the actual stride length as foot members  100  are not pivotally coupled to movable members  112  and the foot members are allowed to translate relative to the movable members. The user may essentially be allowed to “instantaneously” or “dynamically” change his/her stride length by imparting variable forces to foot members  100 . The user may selectively impart forces (e.g., at a beginning or an end of a stride) that vary the path (e.g., the path length or the shape of the path) of foot members  100 . Thus, the user may vary his/her stride so that the path of foot members  100  is varied. In certain embodiments, cam device  102  may assist in imparting forces that change the direction of foot members  100 . 
     In some embodiments, right and left side linkage systems (e.g., foot members  100 , arm links  118 , and/or movable members  112 ) may be cross coupled so that they move in direct and constant opposition to one another. This movement may be accomplished, as shown in  FIG. 4 , with a continuous belt or cable loop. Belt  132  may be a continuous loop supported and constrained by idler pulleys  134 . Idler pulleys  134  may be located at either end of frame  108 . Belt  132  may be coupled to foot members  100  at point  136 . In certain embodiments, belt  132  is configured in a continuous loop coupled to the right side foot member and the left side foot member, thus causing the right and left foot members to move in direct and constant opposition to one another. The geometry of a linkage system (which may include foot members  100 , cam devices  102 , rollers  104 , movable members  112 , crank members  116 , arm links  118 , and/or brackets  130 ) may be such that the belt system (including belt  132  and idler pulleys  134 ) must accommodate either a change in pitch length or a change in distance between idler pulley centers. If the change in pitch length is slight, the change may be accommodated by belt stretch. Alternatively, one of the idler pulleys may be mounted using a spring tensioning system so that the distance between idler pulley centers may increase or decrease slightly during linkage system operation while maintaining tension in the belt loop. 
       FIG. 4A  depicts a side view of an embodiment of an exercise apparatus. The embodiment depicted in  FIG. 4A  operates in a similar manner to the embodiment depicted in  FIG. 4 . In  FIG. 4A , however, roller  104  is coupled to movable member  112  with bracket  130 . Roller  104  may be directly attached to movable member  112  with bracket  130 . Roller  104  may engage foot member  100  through cam device  102 . In  FIG. 4A , the relationship between cam device  102  and roller  104  is inverted, or reversed, compared to the embodiment depicted in  FIG. 4 . In  FIG. 4A , roller  104  and cam device  102  allow translation and create resistive/restoring forces similarly to the embodiment depicted in  FIG. 4 . 
     The embodiments depicted in  FIGS. 4 and 4A  may provide several advantages. In certain embodiments, a user&#39;s stride length may not be constrained by dimensions of components of the crank system (e.g., crank members  116 , pulley device  122 , and/or belt  126 ). Cam device  102  may allow a user to select a longer or shorter stride. A user may select a longer or shorter stride based on his/her own stride length. For example, in certain exercise apparatus, a stride length between about 4 inches and about 40 inches may be selected. For some exercise apparatus, a stride length between about 6 inches and about 36 inches may be selected. For yet other exercise apparatus, a stride length between about 6 inches and about 32 inches may be selected or a stride length between about 8 inches and about 30 inches may be selected. 
     In certain embodiments, a maximum stride length of an apparatus may be between about 35% and about 80% of an overall length of the apparatus. In certain embodiments, a maximum stride length of an apparatus may be at least about 40% of an overall length of the apparatus. In some embodiments, a maximum stride length of an apparatus may be at least about 50%, or at least about 60%, of an overall length of the apparatus. Having a larger maximum stride length to overall length ratio may allow an exercise apparatus to be more compact while maintaining a relatively larger user controlled variation in stride length. Designing and producing such an exercise apparatus may reduce costs (e.g., materials or construction costs) for building the exercise apparatus. 
     In certain embodiments, the exercise apparatus may assist in direction changes of foot members  100  at the end of a stride. In certain embodiments, cam device  102  is located (e.g., near a user&#39;s foot) such that a force equal to or greater than about 50% of the body weight of the user is applied through the cam device and roller  104  (or a spring/damper device) to the exercise apparatus. In some embodiments, nearly full body weight of the user is applied through cam device  102  and roller  104  to the exercise apparatus. This application of a large percentage of body weight may provide a designer the opportunity to create large or significant restoring forces in the exercise apparatus. These significant restoring forces may be advantageous, particularly at the end of a stride when foot members  100  and the linkage assembly must be decelerated and reaccelerated by cam device  102  to accomplish the desired direction change. These large restoring forces may provide assistance in direction change of the user&#39;s feet and may provide a more comfortable and natural exercise pattern for the user. 
     In certain embodiments, cam device  102  is located away from a crank system and/or a brake/inertia system. A housing used to enclose the crank system and/or the brake/inertia system may be of normal and reasonable size because of the location of the crank system and/or the brake/inertia system away from cam device  102 . Thus, a housing may be more reasonable in size since the housing only includes the crank system and/or the brake/inertia system and does not enclose cam device  102  or other components that may increase the size of the housing. Using a smaller housing to enclose the crank system and/or the brake/inertia system may significantly save in costs for materials and construction of an exercise apparatus. These savings may be reflected in a selling price charged for an exercise apparatus. 
     In certain embodiments, use of a pivotal linkage assembly to interact with movable members  112  through cam device  102  allows control of foot articulation angles during use. In certain embodiments, a shorter overall length of frame  108 , and thus the exercise apparatus, is achieved with a pivotal linkage assembly interacting with movable members  112  through cam device  102 . Reducing the overall length of frame  108  may improve the commercial applicability of an exercise apparatus. Larger exercise apparatus may be significantly more expensive to produce and thus have a price that may significantly limit a commercial market for the larger exercise apparatus. Reducing the size of an exercise apparatus may reduce costs (e.g., materials or construction costs) for building the exercise apparatus and allow a lower selling price for the smaller exercise apparatus than a larger exercise apparatus, thus expanding the market for the smaller exercise apparatus. 
       FIG. 5  depicts a side view of an embodiment of an exercise apparatus. The embodiment depicted in  FIG. 5  operates in a similar manner to the embodiment depicted in  FIG. 4 . In  FIG. 5 , however, roller  104  is coupled (e.g., directly attached) to movable member  112  with bracket  130 . Roller  104  may engage foot member  100  through cam device  102 . In  FIG. 5 , the relationship between cam device  102  and roller  104  is inverted, or reversed, compared to the embodiment depicted in  FIG. 4 . In  FIG. 5 , roller  104  and cam device  102  allow translation and create resistive/restoring forces similarly to the embodiment depicted in  FIG. 4 . 
       FIG. 5  depicts an alternative method for cross coupling the right and left side linkage systems. Link pulleys  138  may be rigidly coupled to and rotate in unison with arm links  118 . Idler pulleys  134  may be mounted to frame  108  and may rotate freely. Coupling belt  140  may be a continuous loop that wraps around link pulleys  138 , both right and left sides, and idler pulleys  134 , both upper and lower. Coupling belt  140  may be coupled to link pulleys  138  such that there is limited or no slip in the coupling belt. The coupling can be made by commonly available fasteners, or the belt and pulley may be cogged. In some embodiments, sections of roller chain engaging sprockets, rather than pulleys, may be used. The belt and pulley system, which includes link pulleys  138 , idler pulleys  134 , and/or coupling belt  140 , may serve to cross couple the right side and left side linkage systems so that forward motion of the right side linkage system causes rearward motion of the left side linkage system, and vice versa. This type of cross coupling system may also be used in certain embodiments where foot members  100  cannot be easily or conveniently cross connected by a belt loop, as shown in  FIG. 4 . 
     The method for cross coupling depicted in  FIG. 5  may be used in several embodiments depicted herein. Several embodiments depicted herein as schematics have been simplified for easier discussion of the pertinent features of each embodiment shown. Such depictions may not show one or more features that may be present in a fully functioning exercise apparatus. For example, only the right side linkage and crank system may be shown. In some embodiments, no pulley, belt, and/or brake/inertia system may be shown. In some embodiments, no linkage cross coupling system may be shown. In some embodiments, each of the members in a linkage system may be straight, may be curved, may be unitary, or may be composed of multiple pieces. In some embodiments, rails may be included in or coupled to the frame to engage rollers or wheels. Embodiments shown may operate either with cam device  102  above roller  104 , or with the roller above the cam device (as depicted in  FIG. 5 ). In certain embodiments, the crank and pulley may be in front of a location at which stands on the exercise apparatus (e.g., as shown in  FIG. 5 ) or behind a location at which a user stands on the exercise apparatus (e.g., as shown in  FIG. 6 ). In some embodiments, as shown in  FIG. 6 , rails  110 , or a portion of frame  108  that engages rollers coupled to movable members  112 , may be straight or curved and/or may be inclined. 
       FIG. 6  depicts a schematic of an embodiment of an exercise apparatus.  FIG. 6  shows that the pivotal linkage assembly shown in  FIG. 5  may be used in a rear drive configuration. Crank member  116  may be behind a user while arm link  118  may be in front of the user. In certain embodiments, cam device  102  may be coupled to foot member  100  while roller  104  may be coupled to movable member  112 . In some embodiments, rails  110 , or that portion of frame  108  that is engaged by wheels  114 , may be curved and/or inclined. 
       FIG. 7  depicts a schematic of an embodiment of an exercise apparatus. Movable member  112  may be supported by stationary wheel  142 . Movable member  112  may be free to translate relative to wheel  142 . Cam device  102  may function similarly to the cam device depicted in the embodiment of  FIG. 4 . 
       FIG. 8  depicts a schematic of an embodiment of an exercise apparatus. Movable member  112  may be supported by wheel  114 . Wheel  114  may be located at or near the mid portion of movable member  112 . Cam device  102  and roller  104  may function similarly to the cam device and the roller depicted in the embodiment of  FIG. 4 . Wheel  114  may directly engage frame  108 . In certain embodiments, rails coupled to, or supported by frame  108  may be used. Rails coupled to or supported by frame  108  may be used in any of the embodiments described herein. Examples of designs and uses of rails are described in the embodiments depicted in  FIGS. 4 and 5 . 
       FIG. 9  depicts a schematic of an embodiment of an exercise apparatus. The linkage system depicted in  FIG. 9  may operate in a similar manner to the embodiment depicted in  FIG. 4 . Cam device  102 A may be coupled to foot member  100 . Cam device  102 B may be coupled to movable member  112 . Roller  104  may be located between and engage cam devices  102 A and  102 B. Roller  104  may roll and translate as cam devices  102 A and  102 B translate. Vertical forces applied by a user may be transformed into restoring/resisting forces by cam devices  102 A and  102 B. In some embodiments, cam devices  102 A,  102 B and roller  104  may have gear teeth to ensure positive engagement between the cam devices and the roller. 
       FIG. 10  depicts a schematic of an embodiment of an exercise apparatus. Footpad  128  may be supported and stabilized by two rollers  104  engaging cam device  102 . In an embodiment, cam device  102  has dual cam surfaces, as shown in  FIG. 10 . Cam device  102  may be designed so that a lower lip captures rollers  104  and inhibits footpad  128  from lifting off the rollers during use. The linkage system depicted in  FIG. 10  may operate in a similar manner to the embodiment depicted in  FIG. 4 . Footpad  128 , however, may translate independently of arm link  118 . This independent translation may vary the range of motion of the user&#39;s foot while fixing the range of motion of the user&#39;s arm. 
       FIG. 11  depicts a schematic of an embodiment of an exercise apparatus. Crank member  116  may be pivotally connected to arm link  118 . Restraining link  144  may move in an arcuate pattern about pivot  146  as crank member  116  rotates. In turn, the lower and upper portions of arm link  118  may move in closed ovate paths. Movable member  112  may be pivotally coupled to a lower portion of arm link  118 . Foot member  100  may engage cam device  102  through roller  104 . Foot member  100  may be stabilized by roller  148 . Roller  148  may engage and roll along movable member  112 . In certain embodiments, roller  148  may be captured in a slot in movable member  112 . The slot may have sufficient clearance to allow roller  148  to translate without simultaneously contacting the upper and lower surfaces of the slot. 
     The embodiments depicted in  FIGS. 4–11  show exercise apparatus that generate a closed path in space utilizing movable members  112  that engage a track or a roller associated with frame  108 .  FIG. 12  depicts a side view of an embodiment of an exercise apparatus without tracks or rollers. Frame  108  may include a basic supporting framework and an upper stalk. Crank members  116  may be coupled to a crankshaft and pulley device  122 . Crank members  116 , the crankshaft, and pulley device  122  may be supported by frame  108 . Pulley device  122  may drive brake/inertia device  124  through belt  126 . Crank member  116  may have roller  104  that engages cam device  102 . Cam device  102  may be coupled (e.g., mounted) to foot member  100  or may be a part of the foot member. In certain embodiments, foot member  100  may be a pivotal foot member. Foot member  100  may be pivotally coupled at one end to arm link  118 . Arm links  118  may be pivotally coupled to and supported by frame  108  at point  120 . Arm links  118  may be designed such that the upper portions can be used as grasping members. Foot members  100  may have footpads  128  on which a user may stand. The linkage system may be cross coupled as previously described in the embodiment depicted in  FIG. 5 . 
     In an embodiment, a user ascends an exercise apparatus, stands on footpads  128  and initiates a walking, striding, or jogging motion. The weight of the user on footpad  128  may cause a force to be transmitted through cam device  102  and roller  104 . This force may cause the rotation of crank member  116  and brake/inertia device  124 . The interaction between rollers  104  and cam device  102  may allow relative horizontal displacement of footpads  128  with a restoring force. This interaction may allow variable stride closed path motion of foot members  100 . In some embodiments, brake/inertia device  124  may be located ahead of a user or in front of a user. 
       FIG. 13  depicts a schematic of an embodiment of an exercise apparatus. The embodiment of  FIG. 13  includes several features of the embodiment depicted in  FIG. 12 .  FIG. 13  shows a system that utilizes a multilink connection to foot member  100  to control the orientation and rotation of the foot member. Links  150 A,  150 B,  150 C, and  150 D may work in unison with connector plate  152  to maintain foot member  100  substantially parallel to the floor during use. In some embodiments, a designer may alter the geometry of the linkage system by adjusting the lengths of links  150 A,  150 B,  150 C, and  150 D and/or the position of the connection points to induce a desired rotation pattern for foot member  100 . 
       FIG. 14  depicts a schematic of an embodiment of an exercise apparatus. Frame  108  may include a basic supporting framework and an upper stalk. Movable member  112  may be pivotally coupled to crank member  116 . A forward portion of movable member  112  may engage foot member  100  at roller  154 . Foot member  100  may have cam device  102 . Arm link  118  may be pivotally coupled to and supported by frame  108  at point  120 . Arm link  118  may be pivotally coupled to foot member  100 . Arm link  118  may be designed such that the upper portions can be used as grasping members. 
     Foot member  100  may have footpad  128  on which a user may stand. Roller  104  may be coupled to movable member  112 . Roller  104  may engage cam device  102 . Foot member  100  and movable member  112  may form a reciprocating system that orbits crank shaft  156  at the rear while the forward portion of the system reciprocates along a curvilinear path. 
     A user may ascend the exercise apparatus, stand on footpads  128  and initiate a walking, striding, or jogging motion. The weight of the user on footpad  128  combined with motion of the footpad and foot member  100  may cause a force to be transmitted to movable member  112  through cam device  102 . This force may cause rotation of crank member  116  and a brake/inertia device. The interaction between roller  104  and cam device  102  may allow relative horizontal displacement of foot member  100  with a restoring force. This interaction may allow a variable stride closed path motion of foot member  100 . 
     In some embodiments, cam device  102  and roller  104  may be placed on the top portion of foot member  100 , as depicted in  FIG. 15 . Roller  154  may contact a lower portion of foot member  100 . In some embodiments, cam device  102  may be placed on an upper surface of movable member  112 , as depicted in  FIG. 16 . 
       FIG. 17  depicts a schematic of an embodiment of an exercise apparatus. In an embodiment, a reciprocating system may include foot member  100  and movable member  112 . Wheel  114  may be coupled to foot member  100  and engage frame  108 . Link  158  may couple foot member  100  to arm link  118 . Link  158  may be coupled to foot member  100  at or near a position of roller  104 . The embodiment depicted in  FIG. 17  is a front drive system with the crank positioned in front of a user. 
       FIG. 18  depicts a schematic of an embodiment of an exercise apparatus. Multibar linkage system  160  may be coupled to crank member  116  at point  162 . Multibar linkage system  160  may be supported by frame  108  at point  164 . Points  162  and  164  may be pivot points. The action of multibar linkage system  160  in combination with the rotation of crank member  116  may create a closed ovate path at roller  104 . Cam device  102  may engage roller  104 . 
     In certain embodiments (e.g., embodiments depicted in  FIGS. 4–18 ), cam device  102  may be directly attached to movable member  112  or to foot member  100 . Rigidly fixing the cam device causes the cam device to rotate with and move with the member to which the cam device is directly attached. In some embodiments, controlling rotation of the cam device independently of the member to which the cam device is coupled may be advantageous.  FIG. 19  depicts a schematic of an embodiment of an exercise apparatus with an articulating cam device. Frame  108  may include a basic supporting framework and an upper stalk. Movable member  112  may be pivotally coupled to crank member  116 . Movable member  112  may be supported at an end opposite crank member  116  by wheel  114 . Wheel  114  may engage frame  108 . Foot member  100  may have roller  104  that engages cam device  102 . Cam device  102  may be coupled (e.g., mounted) to pivotal member  166 . Pivotal member  166  may be coupled at point  168  to movable member  112 . Point  168  may be a pivotal point. Pivotal member  166  may be supported at an end distal from point  168  by roller  148 . Roller  148  may engage frame  108 . In certain embodiments, the portion of frame  108  that is engaged by roller  148  may be straight and level. In some embodiments, the portion of frame  108  that is engaged by roller  148  may be inclined and/or curved. Arm link  118  may be pivotally coupled to and supported by frame  108  at point  120 . Arm link  118  may be pivotally coupled to foot member  100 . Arm link  118  may be designed such that upper portions of the arm links can be used as grasping members. Foot member  100  may have footpad  128  on which a user may stand. 
     In an embodiment, a user may ascend the exercise apparatus, stand on footpads  128 , and initiate a walking, striding, or jogging motion. The weight of the user on footpad  128  may cause a force to be transmitted through roller  104 , cam device  102 , and point  168  to movable member  112 . This force may cause the rotation of crank member  116  and a brake/inertia device. The interaction between roller  104  and cam device  102  may allow relative horizontal displacement of foot member  100  with a restoring force. This interaction may allow variable stride closed path motion of foot member  100 . As the system (e.g., foot member  100 ) moves, pivotal member  166  may orient and control the angular position of cam device  102  relative to movable member  112 . Such control of the angular position of cam device  102  may allow a designer to more precisely control the translational forces created by the surface of the cam device interacting with roller  104 . The designer may choose to minimize rotation of the cam device during certain portions of the closed path motion. 
       FIG. 20  depicts a schematic of an embodiment of an exercise apparatus with a dual radius crank. Crank member  116  may be coupled to movable member  112  at journal  170 . Secondary crank member  172  may be rigidly coupled to crank member  116 . Secondary crank member  172  may rotate in unison with crank member  116 . Roller  154  may be coupled to secondary crank member  172  and may define an inner radius of motion. Pivotal member  166  may rest on roller  154 . As crank members  116  and  172  rotate, the angular orientation of a surface of cam device  102  may be controlled by the interaction of pivotal member  166  and roller  154 . A designer may alter the size and position of secondary crank member  172  and the shape of pivotal member  166  to achieve a desired rotational pattern of cam device  102 . 
       FIG. 21  depicts a schematic of an embodiment of an exercise apparatus. Cam device  102  may be pivotally coupled to foot member  100  at point  174 . Pivotal member  166  may be pivotally coupled to cam device  102  at point  176 . Pivotal member  166  may be pivotally coupled to arm link  118  at or near an end of the pivotal member opposite from point  176 . As the system operates, the angular orientation of cam device  102  may be controlled by the interaction of pivotal member  166  and arm link  118 . A designer may alter the linkage geometry to achieve a desired angular control of cam surface  102 . 
       FIG. 22  depicts a schematic of an embodiment of an exercise apparatus. In some embodiments, cam device  102  may be mounted to movable member  112 . In certain embodiments, cam device  102  may be pivotally mounted to movable member  112 . Movable member  112  may be coupled to crank member  116  at journal  170 . The angular orientation of cam device  102  may be controlled by pivotal member  166 . Pivotal member  166  may be pivotally coupled to secondary crank member  172 . Secondary crank member  172  may be rigidly coupled to crank member  116  (as shown in  FIG. 20 ). Secondary crank member  172  may rotate in unison with crank member  116 . A designer may alter the geometry of cam device  102 , pivotal member  166 , and secondary crank member  172  to achieve a desired angular control of the cam device surface. 
       FIG. 23  depicts a schematic of an embodiment of an exercise apparatus. Crank member  116  may be coupled to movable member  112 . Pivotal member  166  may be coupled at its forward end to movable member  112  at point  178 . Point  178  may be a pivot point. Actuation arm  180  may be pivotally coupled at point  182  to movable member  112 . Roller  148  may engage the underside of pivotal member  166 . Roller  154  may engage frame  108 . Roller  154  may be vertically restrained by part  108 A. Part  108 A may be a portion of frame  108  or an addition to the frame. As crank member  116  rotates, the position of movable member  112  may change in space leading to rotation of actuation arm  180  around point  182 . Rotation of actuation arm  180  may cause the rotation of pivoting member  166  relative to movable member  112 . A designer may specify the geometry of the system including the location of point  182  and the length and proportions of actuation arm  180  to create a desired rotation pattern for cam device  102 . 
       FIG. 24  depicts a schematic of an embodiment of an exercise apparatus. Cam device  102  may be coupled to or made an integral part of movable member  112 . Cam device  102  may be located on movable member  112  closest to crank member  116 . In some embodiments, cam device  102  may be located at an end of movable member  112  away from crank member  116 . Movable member  112  may be pivotally coupled to crank member  116 . Movable member  112  may be supported at its rear by frame portion  184 . Frame portion  184  may be a roller engaging portion of frame  108 . A front portion of translating member  186  may engage cam device  102  through roller  104 . A rear portion of translating member  186  may be supported by roller  148 . Roller  148  may engage frame portion  184 . Frame portion  184 , which is engaged by roller  148 , may be inclined and/or curved. Foot member  100  may be pivotally coupled to translating member  186 . Foot member  100  may be supported at its front by a pivotal connection to arm link  118 . Footpad  128  may be coupled to foot member  100 . A designer may select linkage geometry and the shape and orientation of frame portion  184  to create a desired cam device articulation pattern. 
     In some embodiments, rotation of a cam device may be controlled by the use of dual cranks.  FIG. 25  depicts a schematic of an embodiment of an exercise apparatus that uses dual cranks. Frame  108  may include a basic supporting framework and an upper stalk. Movable member  112  may be pivotally coupled to crank members  116 A and  116 B. In an embodiment, crank members  116 A and  116 B are the same size. Movable member  112  may be supported at each end through a pivotal coupling by crank members  116 A and  116 B. Foot member  100  may have roller  104 . Roller  104  may engage cam device  102 . Cam device  102  may be coupled to (e.g., mounted to) movable member  112 . Arm link  118  may be pivotally coupled to and supported by frame  108  at point  120 . Arm link  118  may be pivotally coupled to foot member  100 . Arm link  118  may be designed such that the upper portions can be used as a grasping member. Foot member  100  may have footpad  128  on which a user may stand. Sprockets  188 A and  188 B may be mounted and directly attached through shafts  190 A and  190 B to crank members  116 A and  116 B, respectively. In an embodiment, chain  192  couples sprockets  188 A and  188 B in such a way that crank members  116 A and  116 B are in phase and always at the same angle relative to a horizontal reference line. In certain embodiments, brake/inertia device  124  may be coupled to shaft  190 B to create braking forces and smoothing inertial forces. In some embodiments, chain  192  may be a gearbelt and sprockets  188 A and  188 B may be gearbelt pulleys. 
     In an embodiment, a user may ascend the exercise apparatus, stand on footpads  128 , and initiate a walking, striding, or jogging motion. The weight of the user on footpad  128  may cause a force to be transmitted through roller  104 , cam device  102 , and movable member  112  to crank members  116 A and  116 B. Crank members  116 A and  116 B may move in unison such that every portion of movable member  112  moves in a circular pattern in which the diameter of the circular pattern equals the diameter of the crank members. As a user continues walking, roller  104  may traverse cam device  102 . The combined motion of roller  104  traversing cam device  102  and movable member  112  rotating in a circular pattern may create a closed foot path in space. 
     In some embodiments, as depicted in  FIG. 26 , crank member  116 A may have roller  154  that supports the front of movable member  112 . Thus, crank member  116 A may be out of phase with crank member  116 B and may have a different diameter than crank member  116 B. 
       FIG. 27  depicts a schematic of an embodiment of an exercise apparatus. Cam device  102  may be pivotally coupled to crank members  116 A and  116 B. Crank members  116 A and  116 B may rotate in unison by the action of chain  192  and sprockets  188 A and  188 B. In some embodiments, a gearbelt and gearbelt pulleys may be used instead of a chain and sprockets. In an embodiment, cam device  102  moves in a circular pattern. Roller  104  may engage cam device  102  and support the front of movable member  112 . Foot member  100  may have footpad  128 . Foot member  100  may be pivotally coupled at or near a middle portion of movable member  112 . Foot member  100  may be pivotally coupled at one end to arm link  118 . 
       FIG. 28  depicts a schematic of an embodiment of an exercise apparatus. Cam device  102  may be pivotally coupled to crank member  116 B. The other end of cam device  102  may be supported by roller  148 . Roller  148  may be coupled to crank member  116 A. Crank member  116 A may be out of phase and may have a different diameter than crank member  116 B. 
     In some embodiments, a telescoping member may be pivotally coupled to a frame.  FIG. 29  depicts a schematic of an embodiment of an exercise apparatus. Movable member  112  may be coupled to crank member  116 . Movable member  112  may be hollow. Telescoping member  194  may be pivotally coupled at point  196  to frame  108 . Telescoping member  194  may telescope in and out of movable member  112 . Movable member  112  may slidably engage telescoping member  194 , or rollers may be used as shown in  FIG. 29 . Telescoping member  194  may have shapes including, but not limited to, a channel shape or an I-beam shape. Roller  148  may be coupled to movable member  112  and engage telescoping member  194 . Roller  154  may be coupled to telescoping member  194  at an end of the telescoping member opposite point  196  and engage movable member  112 . Rollers  148  and  154  may allow low friction telescoping action of telescoping member  194 . The action of crank member  116 , movable member  112 , and telescoping member  194  may create a closed ovate path in space at roller  104 . Roller  104  and cam device  102  may create a resistive/restoring force during use. 
     In certain embodiments, a spring/damper device may be used to generate resistive/restoring forces.  FIG. 30  depicts a schematic of an embodiment of an exercise apparatus with a spring/damper device. Movable member  112  may be coupled to crank member  116 . Telescoping member  194  may telescope in and out of movable member  112 . As shown in  FIG. 29 , rollers  148  and  154  may be included in the telescoping system to reduce friction. Spring/damper device  106  may be coupled (e.g., pinned) to telescoping member  194  and movable member  112 . Spring/damper device  106  may include a spring only, a damper only, or a combination spring and damper. Spring/damper device  106  may provide a damping force and/or a spring force that tends to resist extension of telescoping member  194 . Spring/damper device  106  may provide a restoring force to return telescoping member  194  to its nominal position relative to movable member  112 . Thus, a user may increase or decrease stride length during use accordingly. 
       FIG. 31  depicts a schematic of an embodiment of an exercise apparatus with a spring/damper device. Movable member  112  may be coupled to crank member  116 . Footpad  128  may be able to translate along movable member  112  on rollers  104 . In certain embodiments, footpad  128  may slide along movable member  112  to add damping and resistive forces. Spring/damper devices  106  may provide a resistive force and/or a restoring force on contact with footpad  128 . 
       FIG. 32  depicts a schematic of an embodiment of an exercise apparatus with a spring/damper device. Frame  108  may support crank member  116 . Crank member  116  may engage movable member  112 . Foot member  100  may be pivotally coupled at one end through coupler link  198  to arm link  118 . The force resisting/restoring system may include rocker links  200 . Rocker links  200  may be pivotally coupled to movable member  112  and may be pivotally coupled to foot member  100 . Spring/damper devices  106  may provide a resistive and/or a restoring force though rocker links  200  to foot member  100 . 
       FIG. 33  depicts a schematic of an embodiment of an exercise apparatus. Movable member  112  may be coupled to crank member  116 . A forward portion of movable member  112  may be pivotally coupled to supporting link  202 . Arm link  118  may be pivotally coupled to and supported by frame  108  at point  120 . Arm link  118  may be pivotally coupled to foot member  100 . Upper portion of arm link  118  may be used as a grasping member. Crank member  116  may drive pulley device  122 . Pulley device  122  may drive brake/inertia device  124  through belt  126 . 
     Foot member  100  may have footpad  128 . A user of the apparatus may stand on footpad  128 . Roller  104  may be coupled to foot member  100 . Roller  104  may engage movable member  112 . Roller  104  may be free to roll along movable member  112 . Movable member  112  may be formed or fabricated to a specific shape to create certain desired operating characteristics for the apparatus. In certain embodiments, movable member  112  may include cam device  102 . Cam device  102  may be formed as a part of movable member  112 . Cam device  102  may have a curved profile. 
     Belt  140  may be a continuous loop that engages pulley  138  and a similar pulley on an opposite (symmetrical) side of the apparatus (not shown). Belt  140  may cause right side arm link  118  and right side foot member  100  to move in opposition to a left side arm link and a left side foot member. 
     In an embodiment, a user may ascend the exercise apparatus, stand on footpads  128 , and initiate a walking, striding, or jogging motion. The weight of the user on footpad  128  may cause a force to be transmitted through roller  104  to movable member  112 . This force may cause the rotation of crank member  116 , pulley  122 , and a brake/inertia device. As crank member  116  rotates, movable member  112  may undertake closed path motion near roller  104 . Foot member  100  and movable member  112  may interact through roller  104 , which is free to translate along cam device  102 . The nature of the interaction and the magnitude and direction of forces transmitted through roller  104  may be controlled by the shape of cam device  102 . As the user variably applies force to footpad  128 , force may be transmitted through roller  104  to movable member  112  to drive crank member  116 . As crank member  116  rotates, the crank member may impart a force to movable member  112 , which imparts a force to foot member  100  through roller  104  and cam device  102 . These forces may be more significantly imparted at the end or beginning of a step or stride by the user and assist in changing the direction of foot member  100  at the end or beginning of the step by the user. The user is able to determine and select his/her stride length because foot member  100  is not rigidly coupled to movable member  112 . 
       FIG. 34  depicts a schematic of an embodiment of an exercise apparatus. Movable member  112  may be supported at a front end by crank member  116 . Movable member  112  may be supported at a rear end by roller  206  and support link  208 . Secondary crank member  172  may drive connecting link  210  so that support link  208  moves through an arcuate path during rotation of crank member  116 . Rotation of crank member  116  may cause rotation of a front end of movable member  112  through a substantially circular path. 
       FIG. 35  depicts a schematic of an embodiment of an exercise apparatus. Links  214  may be pivotally coupled to each other and to arm link  118 . Links  214  and arm link  118  may form a four bar linkage system. In certain embodiments, links  214  and arm link  118  may operate in unison. A lower link of links  214  may be formed to a curved cam shape. The lower link may engage roller  104 . Roller  104  may be coupled to an end of crank member  116 . During use of the apparatus, links  214  and arm link  118  may articulate and orient a foot of a user and the cam shape of the lower link. The lengths and/or positions of the pivotal coupling points of links  214  may be controlled by a designer of the apparatus to create a desired articulation pattern. During use of the apparatus, arm link  118  may telescope in and out of link  216 . Link  216  may be pivotally coupled to frame  108 . A handle portion may be coupled to link  216 . The handle portion may move in an arcuate, reciprocating path. 
       FIG. 36  depicts a schematic of an embodiment of an exercise apparatus. The linkage system in the embodiment shown in  FIG. 36  operates similarly to the linkage system in the embodiment shown in  FIG. 35 . Arm link  118  may slidably engage member  218 . An upper portion of arm link  118  (e.g., an upper handle portion) may extend through member  218 . The upper portion of arm link  118  may move with both horizontal and vertical displacement. The upper portion of arm link  118  may move through a closed path. 
     In some embodiments, an exercise apparatus may provide a curvilinear path of motion.  FIG. 37  depicts a side view of an embodiment of an exercise apparatus.  FIG. 37A  depicts a top view of an embodiment of the exercise apparatus depicted in  FIG. 37 . Frame  108  may include a basic supporting framework and an upper stalk. Frame  108  may be any structure that provides support for one or more components of an exercise apparatus. In certain embodiments, all or a portion of frame  108  may remain substantially stationary during use. For example, all or a portion of frame  108  may remain substantially stationary relative to a floor on which the exercise apparatus is used. 
     In  FIG. 37 , both right and left sides of the linkage system are shown. The right and left sides of the linkage system may be used for the right and left feet of a user, correspondingly. The right and left sides may be mirror images along a vertical plane oriented along the center of the machine as viewed from above, as shown in  FIG. 37A . 
     Left and right movable members  112  may be pivotally coupled at point  204  to actuator block  220 . Roller  206  may be coupled to an end of crank member  116 . Rotation of crank member  116  may cause the rising and falling motion of movable member  112  in an arcuate pattern shown by arrow  226 . Arm links  118  may be pivotally coupled to and supported by frame  108  at point  120 . Arm links  118  may be pivotally coupled to foot members  100 . Arm links  118  may be designed so that the upper portions can be used as grasping members (e.g., handles). 
     Crank members  116  may drive pulley device  122 , which in turn may drive brake/inertia device  124  using belt  126 . 
     Foot member  100  may have footpads  128  or any other surface on which a user may stand. Footpad  128  may be any surface on which a user&#39;s foot resides during use of an exercise apparatus (e.g., the footpad may be a foot pedal). Roller  104  may be coupled to foot member  100  by bracket  130 . Roller  104  may engage movable member  112  at cam device  102 . Cam device  102  may be formed to a specific shape to provide desired operating characteristics. 
     Cam device  102  may have a long length cam surface compared to the length of crank member  116 . In certain embodiments, cam device  102  may have a cam surface with a length that exceeds a crank diameter of the crank system. The crank radius of the crank system is generally the length of one crank member  116 . Thus, the crank diameter is twice the length of one crank member  116 . In some embodiments, the length of the cam surface of cam device  102  is at least about 1.5 times the crank diameter of the crank system. In some embodiments, the length of the cam surface of cam device  102  is at least about 2 times the crank diameter of the crank system. The length of the cam surface of cam device  102  is the path length along the cam surface (e.g., the length along a curved surface of the cam device). The long length of the cam surface compared to the crank diameter of the crank system may provide a long stride length on a relatively compact exercise apparatus. 
     The forward portion of movable member  112  is shown to be straight in  FIG. 37 . Movable member  112  may, however, be curved and/or include a bend. In certain embodiments, movable member  112  is made of a solid or unitary construction. In some embodiments, movable member  112  may include multiple components coupled or fastened to achieve a desired performance. In certain embodiments, cam device  102  and movable member  112  may be incorporated in a single unit such as a bent or curved tube or bar. Similarly, foot members  100  and arm links  118  may be straight, bent, or curved. Foot members  100  and arm links  118  may be unitary or may include multiple components. 
     In an embodiment, a user ascends the exercise apparatus, stands on footpads  128  and initiates a walking, striding, or jogging motion. The weight of the user on footpads  128  combined with motion of the footpads and foot members  100  causes a force to be transmitted to movable members  112  through roller  104  and cam device  102 . This force in turn causes the rotation of crank members  116 , pulley device  122 , and brake/inertia device  124 . As crank members  116  rotate, movable members  112  undertake a rising and falling motion in an arcuate pattern. In an embodiment, foot member  100  and reciprocating member  112  interact through roller  104 , which is free to translate relative to movable member  112  at cam device  102 . The nature of the interaction and the magnitude and direction of the forces transmitted through roller  104  may be controlled by the shape and/or orientation of cam device  102 . 
     The rising and falling motion of the movable members  112  may induce a striding pattern. As shown in  FIG. 37 , when crank member  116  is in a downward position, movable member  112  supported by roller  206  has a generally rearward slope toward the back of the machine. This rearward slope induces foot member  100  to move rearward as the user applies force through the foot member. When crank member  116  is an upward position, movable member  112  supported by roller  206  on that crank member has a generally forward slope toward the front of the machine. This forward slope induces foot member  100  to move forward. Therefore, the rising and falling motion of movable members  112  may induce a forward and rearward motion in foot members  100 . This forward and rearward motion in foot members  100  may allow for various paths of motion related to the arcuate pattern represented by arrow  226 . Examples of these various paths of motion relative to the arcuate pattern represented by arrow  226  are shown in  FIG. 38 . In certain embodiments, an exercise apparatus (e.g., the embodiment depicted in  FIG. 37 ) may provide paths of motion that become more oblong in shape as the stride length increases, as shown in  FIG. 38 . 
     The right and left side linkage systems (e.g., foot members  100 , arm links  118 , and/or reciprocating members  112 ) may be cross coupled so that they move in a direct and constant opposition to one another. Link pulleys  138  may be rigidly coupled to and rotate in unison with arm links  118 . Idler pulleys  134  may be mounted to frame  108  and may rotate freely. Coupling belt or cable  140  may be a continuous loop that wraps around link pulleys  138 , both right and left sides, and idler pulleys  134 , both upper and lower. Coupling belt or cable  140  may be coupled to link pulleys  138  such that there is limited or no slip in the coupling belt or cable. The coupling can be made by commonly available fasteners, or a cogged belt and pulley may be used. In some embodiments, sections of roller chain engaging sprockets, rather than pulleys, may be used. The belt and pulley system, which includes link pulleys  138 , idler pulleys  134 , and/or coupling belt  140 , may serve to cross couple the right side and left side linkage systems so that forward motion of the right side linkage system causes rearward motion of the left side linkage system, and vice versa. 
     The intensity of exercise for a user may be varied by altering the geometry of the linkage system. For example, actuator block  220  may be repositioned higher or lower by the action of rotating motor  224  and leadscrew  222 . By raising actuator block  220 , the user must step higher at the beginning of the stride. This higher step effectively increases the perceived striding or climbing angle and increases the intensity of the exercise. Rotating motor  224  may be controlled by a user interface and/or control circuitry. 
       FIG. 39  depicts a schematic of an embodiment of an exercise apparatus. Movable member  112  may be supported at a front end and a rear end by support links  208 . Connecting link  210  may couple crank member  116  to forward support link  208 . Rotation of crank member  116  may cause movable member  116  to rise and fall in an arcuate path. 
       FIG. 40  depicts a schematic of an embodiment of an exercise apparatus. Movable member  112  may be supported by roller  154 . Roller  154  may be coupled (e.g., mounted) to an end of crank member  116 . Rotation of crank member  116  may cause movable member  112  to rise and fall in an arcuate path. Roller  104  may also rise and fall in an arcuate path. 
       FIG. 41  depicts a schematic of an embodiment of an exercise apparatus. Movable member  112  may be coupled to telescoping member  194 . Telescoping member  194  may move in and out of movable member  112 . Rotation of crank member  116  may cause telescoping member  194  to rise and fall in an arcuate path. Roller  104  may also rise and fall in an arcuate path. 
     In some embodiments, an exercise apparatus may provide relatively linear path of motion for a user.  FIG. 42  depicts a schematic of an embodiment of an exercise apparatus. Crank member  116  may be coupled to connecting link  210 . Rotation of crank member  116  may cause reciprocation of traveling member  212 . Reciprocation of traveling member  212  may be horizontal reciprocation. Cam device  102  may engage roller  104 . Cam device  102  may move along with traveling member  212 . 
       FIG. 43  depicts a schematic of an embodiment of an exercise apparatus. Crank member  116  may be coupled to movable member  112 . Rotation of crank member  116  may cause reciprocation (e.g., horizontal reciprocation) of movable member  112  at roller  104  and wheel  114 . Roller  104  may be mounted coaxially with wheel  114 . Roller  104  may move in a reciprocating pattern (e.g., a horizontal reciprocating pattern). Cam device  102  may engage roller  104 . 
     In this patent, certain U.S. patents, U.S. patent applications, and other materials (e.g., articles) have been incorporated by reference. The text of such U.S. patents, U.S. patent applications, and other materials is, however, only incorporated by reference to the extent that no conflict exists between such text and the other statements and drawings set forth herein. In the event of such conflict, then any such conflicting text in such incorporated by reference U.S. patents, U.S. patent applications, and other materials is specifically not incorporated by reference in this patent. 
     Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the invention. It is to be understood that the forms of the invention shown and described herein are to be taken as the presently preferred embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features of the invention may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description of the invention. Changes may be made in the elements described herein without departing from the spirit and scope of the invention as described in the following claims.