Patent Publication Number: US-7708669-B2

Title: Pendulum striding exercise apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Application is a Continuation of application Ser. No. 11/005,223 filed on Dec. 6, 2004, which application claims the benefit of U.S. Provisional Patent Application No. 60/526,802 entitled “Pendulum Striding Exercise Device” to Robert E. Rodgers, Jr., filed on Dec. 4, 2003; U.S. Provisional Patent Application No. 60/585,787 entitled “Pendulum Striding Exercise Device” to Robert E. Rodgers, Jr., filed on Jul. 6, 2004; and U.S. Provisional Patent Application No. 60/619,824 entitled “Pendulum Striding Exercise Device” to Robert E. Rodgers, Jr., filed on Oct. 18, 2004. 
    
    
     TECHNICAL FIELD 
     The present invention relates generally to an exercise apparatus. Certain embodiments relate to exercise apparatus that may allow exercise such as simulated walking, striding, jogging, and/or climbing. 
     BACKGROUND OF THE INVENTION 
     Exercise devices have been in use for years. Some typical exercise devices that simulate walking, jogging, or climbing include cross country ski machines, stair climbing machines, elliptical motion machines, and pendulum motion machines. 
     In many exercise apparatus, the user&#39;s foot is constrained during exercise to patterns that may not accurately represent the typical path and/or position of a foot during walking and/or jogging. For example, cross country ski machines may not allow a user to lift the front of his/her foot above a flat plane defined by the top of the pedal or footpad. Elliptical machines may provide inertia that assists in changing directions of the foot pedals, which may make the exercise smoother and more comfortable. Elliptical machines may, however, constrain a user&#39;s foot to the mechanically defined elliptical path of the footpads or foot pedals. The elliptical path may be too long for shorter users or too short for taller users. Thus, an elliptical apparatus may not accommodate a variety of users. In addition, a jogging stride is longer than a walking stride so a fixed stride length apparatus may not optimally simulate several different types of exercise activities. 
     Pendulum motion exercise apparatus may allow variable stride length. The user&#39;s feet, however, may be constrained to follow the same arcuate path in both forward and rearward motion. Such motion may not accurately simulate a walking, striding, jogging, or climbing motion. Certain pendulum motion exercise apparatus may have a fixed pendulum length. A fixed pendulum length may not allow for foot lift or vertical amplitude in the motion of the foot, and thus, may not provide naturally accommodating foot motion. Other pendulum motion exercise apparatus may have relatively short pendulum lengths that may not properly accommodate the path of motion of the foot or legs of the human body. 
     BRIEF SUMMARY OF THE INVENTION 
     An exercise apparatus may include a frame. The frame may include at least a portion that remains substantially stationary during use. A crank system may be coupled to the frame. The crank system may include one or more crank members. A brake/inertia device may be coupled to the crank system. In certain embodiments, an exercise apparatus may include a pivotal linkage pendulum system. A pivotal linkage pendulum system may be coupled to the crank system. A pivotal linkage pendulum system may include one or more link members. In certain embodiments, an upper pivot point of a link member may be coupled to the crank system. In some embodiments, the upper pivot point of the link member is coupled to the crank system through a movable member. The upper pivot point of the link member may move in a path during use. A foot member may be coupled to at least one of the link members. In some embodiments, a foot member may be coupled to a lower pivot point of at least one of the link members. The foot member may include a footpad. 
     In some embodiments, a pivotal linkage pendulum system may include a movable member. The movable member may be coupled to one or more link members. An upper pivot point of at least one of the link members may be coupled to a portion of the movable member. In certain embodiments, the upper pivot point of the at least one of the link members is at an upper end of the link member. The portion of the movable member may move in a back and forth path of motion. In some embodiments, the portion of the movable member may move in a closed path of motion. 
     In an embodiment, a movable member is coupled to and at least partially supported by the frame at or near a first end of the movable member. The movable member may be coupled to and at least partially supported by the crank system at or near a second end of the movable member. The portion of the movable member coupled to the upper pivot point of the at least one of the link members may be between the first end and the second end of the movable member. In some embodiments, the portion of the movable member coupled to the upper pivot point of the at least one of the link members is near the second end of the movable member. 
     In certain embodiments, a pivotal linkage pendulum system may include one or more link members. An upper pivot point of at least one of the link members may be coupled to the crank system such that the upper pivot point of the link member moves in a closed path. A foot member may be coupled to one or more of the link members. The foot member may include a footpad. In certain embodiments, a majority of a path of motion of the footpad is below the closed path. In some embodiments, substantially all of a path of motion of the footpad is below the closed path. 
     In certain embodiments, a distance between a footpad and an upper pivot point of a link member that moves in a path (e.g., a closed path or a back and forth path) is at least about 3 times the length of at least one crank member. In some embodiments, a distance between a footpad and an upper pivot point of a link member that moves in a path (e.g., a closed path or a back and forth path) is at least about 3 times a vertical amplitude of a path of motion of the footpad. In certain embodiments, a hip of a majority of users of the apparatus is positioned near at least a portion of the path of motion of an upper pivot point of a link member. 
     In certain embodiments, a majority of the path of an upper pivot point of a link member is positioned in front of a footpad plane when the footpad is at a center of its path of motion. The footpad plane may be located at a center of a footpad. In certain embodiments, a majority of a crank system is positioned in front of a footpad plane when the footpad is at a center of its path of motion. In some embodiments, a majority of the crank system is positioned near a footpad plane when the footpad is at a center of its path of motion. In some embodiments, a majority of the crank system is positioned behind a footpad plane when the footpad is at a center of its path of motion. 
     The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention. 
    
    
     
       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: 
         FIG. 1  depicts an embodiment of a human leg moving through a walking, striding, jogging, or climbing motion. 
         FIG. 1A  depicts embodiments of paths of a user&#39;s foot moving through a walking, striding, jogging, or climbing motion. 
         FIG. 2  depicts an embodiment of a linkage system with a relatively long pendulum length compared to a crank radius. 
         FIG. 3  depicts an embodiment of a linkage system with a relatively short pendulum length compared to a crank radius. 
         FIG. 4  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 5  depicts a path that a user&#39;s foot may follow during exercise using an embodiment of an exercise apparatus. 
         FIG. 6  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 7  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 8  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 9  depicts a top view of an embodiment of an exercise apparatus. 
         FIG. 10  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 10A  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 11  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 11A  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 12  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 13  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 14  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 15  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 16  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 16A  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 17  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 18  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 19  depicts a side view of an embodiment of an exercise apparatus. 
         FIG. 20  depicts examples of embodiments of back and forth paths of motion. 
         FIG. 21  depicts examples of embodiments of closed paths of motion. 
     
    
    
     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 OF THE INVENTION 
     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. The term “support” means a first element, directly or indirectly, locates or positions a second element by pushing or pulling on the second element. The first element may be directly attached or coupled to the second element when providing support. The first element may be in compression while pushing or in tension while pulling on the second element. 
     The term “path” means any type of path that an object (e.g., a foot, a footpad, a link member, a movable member, or a coupling) or a point in space may undertake during motion. For example, a path may include a closed path or a back and forth path. 
     A “back and forth path of motion” means motion along a curved or straight line with two end points. The back and forth motion moves along the same line but in opposite directions. Back and forth motion may be substantially horizontal motion, substantially vertical motion, or a combination of horizontal motion and vertical motion. Examples of back and forth paths of motion are depicted in  FIG. 20 . 
     A “closed path of motion” means motion along a continuous path that encloses an area. A closed path of motion has no end points. A closed path of motion may have many different shapes. The shape of a closed path may depend on the generating linkage mechanism. For example, a closed path may be an orbital path, 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. In some embodiments, a closed path may be elliptical, orbital, or oblong. Examples of closed paths of motion are depicted in  FIG. 21 . 
     The term “pendulum” means a body suspended from a pivoting point so that it swings back and forth. The term “amplitude” means the magnitude or extent of movement from a specified location (e.g., a starting position or an equilibrium position). 
     The phrase “average height user” means a user that has a height near an average human height. Mean height for males is about 5′9″ and mean height for females is about 5′4.5″ (data from U.S. Department of Health and Human Services). Thus, an average height user may be defined as a user with a height of about 5′6″ or 5′7″. An exemplary image of an average height user is used in one or more of the drawings described herein. A “majority of users” may have a height between about 5′ and about 6′4″. For the purposes of this patent, “a hip of an average height user” refers to a location of the hip of an average height user and “a hip of a majority of users” refers to a location of the hip of a majority of users. Users with similar heights may, however, have different torso and/or leg lengths that vary the position of each user&#39;s hip relative to other parts (e.g., the feet) of the user&#39;s body. Thus, there may be variations in the location of a user&#39;s hip between individuals. 
       FIG. 1  depicts an embodiment of a human leg moving through a walking, striding, jogging, or climbing motion. Leg  80 , when fully extended, may act as a pendulum. Hip joint  82  may be a top of the pendulum about which leg  80  moves. Articulation of the ankle and knee joints may result in path  84  of the foot with a foot lift.  FIG. 1A  depicts several embodiments of path  84  that a user&#39;s foot may move through using an exercise apparatus as described herein. Path  84  may have a vertical amplitude “h” at a center of the path. Path  84  may have several different shapes due to variations in a horizontal amplitude of the path, as shown in  FIG. 1A . The vertical amplitude “h”, however, may remain substantially the same for the various embodiments of path  84  for an exercise apparatus with a fixed geometry. At or near walking or jogging speeds, “h” may be a relatively small percentage of extended leg length “L”. Thus, a mechanical system that more accurately accommodates the natural path of motion of a user&#39;s leg and foot may include a pendulum system having a pendulum length that is relatively long compared to vertical amplitude “h”. 
     A vertical amplitude of a foot path of motion may be defined by a geometry of a crank system (e.g., a crank radius) and a linkage system (e.g., a pivotal linkage pendulum system).  FIG. 2  depicts an embodiment of a linkage system with a relatively long pendulum length compared to a crank radius.  FIG. 3  depicts an embodiment of a linkage system with a relatively short pendulum length compared to a crank radius. As shown in  FIG. 2 , pendulum angle  86  may be relatively small with pendulum length “P” relatively long compared to crank radius  88 . A resultant horizontal force as a user steps on a foot member (e.g., a foot pedal) is equal to the stepping force multiplied by the tangent of pendulum angle  86 . A resultant horizontal force in the embodiment depicted in  FIG. 2  may be a relatively small portion (e.g., approximately 10%) of the stepping force. In  FIG. 3 , pendulum length “P” is relatively short compared to crank radius  88 . A resultant horizontal force in the embodiment depicted in  FIG. 3  may be a relatively large portion (e.g., approximately 100%) of the stepping force. Therefore, an exercise apparatus with a relatively long pendulum length “P” compared to crank radius  88  (e.g., a pendulum length at least about 3 times the crank radius) may provide a smaller resultant horizontal force. Thus, such an exercise apparatus may provide a smoother, a more comfortable, and a more accommodating motion for a user of the apparatus. 
     In certain embodiments, a pendulum motion exercise apparatus may include a brake/inertia system or device. Brake/inertia systems may receive energy, store energy, and deliver energy in an exercise apparatus. For example, a brake/inertia system may receive energy as a user steps downward at the beginning of a stride. The brake/inertia system may store the received energy. The stored energy may be delivered back to the exercise apparatus or the user to assist in lifting a linkage assembly or a portion of a linkage assembly (e.g., a foot member) over the top of a step or a stride. This energy transfer may assist in providing a more natural and a more comfortable walking, striding, jogging, and/or climbing motion for a user of an exercise apparatus. 
     In certain embodiments, an exercise apparatus may include a brake/inertia system and provide for a foot path of motion in which a vertical amplitude of the foot path of motion is relatively small compared to a pendulum length of the foot path of motion. Such an exercise apparatus may provide more natural, smoother, more comfortable, and more accommodating function and path of motion for a user of the exercise apparatus. 
       FIG. 4  depicts a side view of an embodiment of an exercise apparatus. Frame  100  may include a basic supporting framework and an upper stalk. Frame  100  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  100  may remain substantially stationary during use. For example, all or a portion of frame  100  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. For example, an exercise apparatus would be “stationary” if the apparatus is operated in one location (in contrast to a movable exercise apparatus such as an ordinary bicycle), even if the apparatus wobbles or vibrates during use. 
     Foot members  122  may have footpads  124  or any other surface on which a user may stand. Footpad  124  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  124  may be a portion of foot member  122 . Footpad plane  125  is a plane that intercepts footpad  124  at a right angle approximately near a center of the footpad, as shown in  FIG. 4 . Footpad plane  125 , as depicted in  FIG. 4 , may be used in any of the embodiments and drawings described herein. 
     Link members  152   a ,  152   b ,  152   c ,  152   d  may be components of a multibar linkage system (e.g., a pivotal linkage pendulum system). In certain embodiments, a pivotal linkage pendulum system may include one or more pendulum members (e.g., link members  152   a ,  152   b ,  152   c ,  152   d ), foot members (e.g., foot members  122 ), and footpads (e.g., footpads  124 ). A pivotal linkage pendulum system may include left and right portions that are mirror images of each other. In certain embodiments, the left and right portions of a pivotal linkage pendulum system may move in opposition to each other. In an embodiment, link members  152   a ,  152   d  are coupled to (e.g., pivotally coupled to) foot members  122 . Link members  152   a  may be coupled to (e.g., pivotally coupled to) frame  100  at point  130 . Link members  152   a  may be supported by frame  100  at point  130 . Point  130  is a location on frame  100  that may include an elongated axis perpendicular to the plane of  FIG. 4  (i.e., the axis projects in or out of the two dimensional plane depicted in  FIG. 4 ) for coupling members (e.g., link members  152   a ) to the frame. For example, point  130  may be a location with an axis or a shaft that couples the frame to both right and left side link members. In certain embodiments, link members  152   a  may support an end of foot members  122  coupled to the link members. Link members  152   d  may also support foot members  122 . Foot members  122  may be coupled to a lower end of a pivotal linkage pendulum system. For example, foot members  122  may be coupled to link members  152   d , which are in a lower end of the pivotal linkage pendulum system. 
     Link member  152   c  may be coupled to and supported by movable member  104  at point  132 . An “upper pivot point” of link member  152   c  may be coupled to movable member  104  at point  132 . In certain embodiments, the upper end of link member  152   c  may be the upper pivot point coupled to movable member  104  at point  132 . In some embodiments, another portion of link member  152   c  may be coupled to movable member  104  at point  132  (e.g., the upper pivot point on the link member may be near the upper end of the link member). Point  132  is a location that may include an elongated axis perpendicular to the plane of  FIG. 4  (i.e., the axis projects in or out of the two dimensional plane depicted in  FIG. 4 ) for coupling two or more members together (e.g., link members  152   c  and movable members  104 ). For example, point  132  may be a location with an axis or a shaft that couples a right side movable member to a right side link member. A similar point or location may be on a left side of the exercise apparatus for coupling a left side movable member to a left side link member. 
     Link member  152   c  may act as a pendulum moving about an upper pivot point of the link member, which is coupled to movable member  104 . The upper pivot point of link member  152   c  represents a top of the pendulum. Thus, link member  152   c  acts as a pendulum supported by movable member  104  at point  132 , which is the point of coupling between the movable member and the upper pivot point of the link member. 
     In certain embodiments, movable member  104  may be a member of a pivotal linkage pendulum system. In some embodiments, movable members  104  may be motion generating members. Movable members  104  may be supported by frame  100  at point  130 . Movable members  104  may rotate or pivot about point  130 . Crank members  114  may engage movable members  104  with rollers  106 . During use, as crank members  114  rotate, the crank members may displace movable members  104  and cause an end of the movable members to move in a back and forth path of motion at point  132  centered about point  130 , which is approximately represented by arrow  134  in  FIG. 4 . The back and forth path of motion of movable member  104  may cause the upper pivot point of link member  152   c  coupled to the movable member at point  132  to move in a back and forth path of motion. The back and forth path of motion of the upper pivot point of link member  152   c  may include at least some vertical component. In certain embodiments, a hip of a majority of users may be positioned near at least a portion of the back and forth path of motion of the upper pivot points of link members  152   c . In some embodiments, a hip of an average height user may be positioned near at least a portion of the back and forth path of motion of the upper pivot points of link members  152   c . In certain embodiments, an exercise apparatus with movable members that move in a back and forth path of motion may be easier to use and learn than certain embodiments of other exercise apparatus because there is no preferred direction of movement for the movable members, as there may for an exercise apparatus with movable members that move in a closed path of motion. 
     Crank members  114  may cause right and left movable members  104  to move in opposition to each other (i.e., the right movable member moves downwards as the left movable member moves upwards, and vice versa). Crank members  114  may be coupled to pulley device  116 . Pulley device  116  may be coupled to brake/inertia device  118  by belt  120 . Thus, rotation of pulley device  116  may cause rotation of brake/inertia device  118 . 
     In certain embodiments, a “crank system” may include, in a generic case, crank member  114  coupled (either directly attached or indirectly attached) to pulley device  116 . 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. Another example is a crank system with multiple crank members. In certain embodiments, a crank drive 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  100 . In some embodiments, a crank system may be indirectly coupled to frame  100  with one or more components coupling the crank system to the frame. In certain embodiments, a majority of a crank system may be positioned in front of footpad plane  125  when footpad  124  is at a center of its path of motion, as depicted in the embodiment of  FIG. 4 . In some embodiments, a majority of a crank system may be positioned near footpad plane  125  when footpad  124  is at a center of its path of motion, as depicted in the embodiment of  FIG. 11 . In some embodiments, a majority of a crank system may be positioned behind footpad plane  125  when footpad  124  is at a center of its path of motion, as depicted in the embodiment of  FIG. 7 . 
     A brake/inertia device (e.g., brake/inertia device  118 ) may provide a load to affect the intensity of a cardiovascular workout. A brake/inertia device may include an energy-storing member (e.g., a flywheel) that is coupled to a linkage or crank system to increase inertia of the system. In some embodiments, a brake/inertia device may provide for a variable load. In some embodiments, a brake/inertia device may store energy provided by a user during a portion of an exercise motion and then may provide at least a portion of such stored energy back to the user during another portion of the exercise motion. 
     As shown in  FIG. 4 , movable member  104  may be straight and foot member  122  may be bent. In some embodiments, however, movable members  104  and/or foot members  122  may be straight, bent in one or more places, and/or curved. In certain embodiments, movable member  104  and/or foot members  122  are made of a solid or unitary construction. In some embodiments, movable member  104  and/or foot members  122  may include multiple components coupled or fastened to achieve a desired performance. Similarly, arm link members  108  and/or other link members may be straight, bent, or curved. Arm link members  108  and/or other link members may be unitary or may include multiple components. 
     In an embodiment, as a user ascends the exercise apparatus, the user stands on footpads  124  and initiates a walking, striding, jogging, or climbing motion. The weight of the user on footpads  124  combined with motion of the footpads and foot members  122  may cause a force to be transmitted to movable members  104 . This transmitted force may cause rotation of crank members  114 , pulley device  116 , and brake/inertia device  118 . As movable members  104  move, footpads  124  may alternately rise and fall. This rising and falling path of motion may simulate the rising and falling motion of a foot of a user during actual walking, striding, jogging, or climbing. 
     As a user steps downward at a front of a step or stride, a force may be transmitted through the pivotal linkage pendulum system to brake/inertia device  118 . Brake/inertia device  118  may receive and store at least some of this transmitted energy. Brake/inertia device may deliver at least some of the stored energy back to the exercise apparatus to assist in lifting the pivotal linkage pendulum system over the top of a step or a stride. 
     Arm link members  108  may be coupled to link members  152   a . In some embodiments, arm link members  108  may be included as a portion of link members  152   a  (i.e., arm link members  108  and link members  152   a  are made of a unitary construction). Arm link members  108  may include handles or other devices that may be grasped by a user of the exercise apparatus. 
     In certain embodiments, the right and left portions of a pivotal linkage pendulum system may be cross coupled. Cross coupling may cause the right and left portions to move in opposition. As shown in  FIG. 4 , a cross coupling system may include belt  182 , pulley  186   r , a mirror image pulley on a left side of the exercise apparatus, and idler pulleys  184   u  and  184   l . Idler pulleys  184   u  and  184   l  may be coupled to pulley  186   r  and its mirror image pulley by belt  182 . Pulley  186   r  and its mirror image pulley may be directly attached (e.g., rigidly attached) to link members  152   a . Belt  182  may be a continuous belt that causes pulley  186   r  and its mirror image pulley to rotate in direct opposition to one another so that the right and left side portions of the pivotal linkage pendulum system are cross coupled. 
       FIG. 5  depicts a path that a footpad (i.e., a user&#39;s foot) may follow during exercise using an embodiment of an exercise apparatus (e.g., the embodiment depicted in  FIG. 4 ). A vertical amplitude “h” of the path may be determined by a geometry of the crank system (e.g., a length of a crank member) and/or a geometry of the pivotal linkage pendulum system. The geometry of the crank system and/or the geometry of the pivotal linkage pendulum system may determine a vertical amplitude of the back and forth path of motion of movable member  104 , depicted in  FIG. 4 . The back and forth path of motion of movable member  104  causes the upper pivot point of link member  152   c  to move in a back and forth path of motion. This back and forth path of motion may include at least some vertical component. The vertical amplitude of the back and forth path of motion of the upper pivot point of link member  152   c  may determine the vertical amplitude “h” of the path of footpad  124 . In certain embodiments, a vertical amplitude “h” of the path of a footpad (e.g., footpad  124 ) may be similar in magnitude to a vertical amplitude of a back and forth path of motion of an upper pivot point of a link member (e.g., link member  152   c ). In certain embodiments, a vertical amplitude of the back and forth path of motion of an upper pivot point of a link member (e.g., link member  152   c ) may be similar in magnitude to a length of a crank member (e.g., crank member  114 ). Thus, a vertical amplitude “h” of the path of a footpad (e.g., footpad  124 ) may be similar in magnitude to a length of a crank member (e.g., crank member  114 ). 
     In  FIG. 5 , a horizontal amplitude “d” of the path may be determined by an amount of force applied by a user to a footpad. A user may undertake an arcuate, substantially vertical climbing motion by limiting the horizontal amplitude of the path. A vertical climbing motion may be approximated when a vertical amplitude of a path of motion of a footpad is greater than a horizontal amplitude of the path of motion of the footpad. In certain embodiments, a user may be allowed to “instantaneously” or “dynamically” adjust his/her stride length (e.g., a horizontal amplitude of a path). The user may essentially be allowed to instantaneously or dynamically change his/her stride length by imparting variable forces to foot members  122  or footpads  124 , depicted in  FIG. 4 . The user may selectively impart forces that vary the stride length and allow more accurate simulation of a walking, striding, jogging, and/or climbing motion. 
     An exercise apparatus may have a pendulum length that is relatively long compared to a vertical amplitude of a path of motion of a footpad (e.g., footpad  124  depicted in  FIG. 4 ) or to a length of a crank member (e.g., crank member  114  depicted in  FIG. 4 ). In certain embodiments, a pendulum length may approximate the length of a majority of users&#39; legs. For example, a pendulum length may be within about 10% of the length of a majority of users legs. In some embodiments, a pendulum length may approximate the length of an average height user&#39;s legs. A footpad may be located at or near an end of a pendulum member (e.g., at or near an end of a link member such as link member  152   c ). Thus, a distance between a footpad (e.g., footpad  124 ) and a top of a pendulum (e.g., the upper pivot point of link member  152   c  (i.e., point  132 ) depicted in  FIG. 4 ) may be representative of a pendulum length of an apparatus. 
     In certain embodiments, the distance between a footpad (e.g., footpad  124 ) and a top of a pendulum (e.g., the upper pivot point of link member  152   c ) may be at least 3 times a vertical amplitude of a path of motion of the footpad. In some embodiments, the distance between a footpad (e.g., footpad  124 ) and a top of a pendulum (e.g., the upper pivot point of link member  152   c ) may be at least 4 times, or at least 5 times, a vertical amplitude of a path of motion of the footpad. In certain embodiments, the distance between a footpad (e.g., footpad  124 ) and a top of a pendulum (e.g., the upper pivot point of link member  152   c ) may be at least 3 times a length of a crank member (e.g., crank member  114 ). In some embodiments, the distance between a footpad (e.g., footpad  124 ) and a top of a pendulum (e.g., the upper pivot point of link member  152   c ) may be at least 4 times, or at least 5 times, a length of a crank member (e.g., crank member  114 ). 
     In an embodiment, the distance between a footpad (e.g., footpad  124 ) and a top of a pendulum (e.g., the upper pivot point of link member  152   c ) is greater than about 2 feet. In some embodiments, the distance between a footpad (e.g., footpad  124 ) and a top of a pendulum (e.g., the upper pivot point of link member  152   c ) is greater than about 1 foot, or greater than about 1½ feet. In certain embodiments, the distance between a footpad (e.g., footpad  124 ) and a top of a pendulum (e.g., the upper pivot point of link member  152   c ) is between about 1 foot and about 5 feet, or between about 2 feet and about 4 feet. 
       FIG. 6  depicts a side view of an embodiment of an exercise apparatus. Right side link member  152 R and left side link member  152 L may be coupled to (e.g., pivotally coupled to) right side sprocket  162 R and a corresponding left side sprocket, respectively. In certain embodiments, link member  152 R and left side link member  152 L may be coupled to right side sprocket  162 R and a corresponding left side sprocket at right side offset point  164 R and left side offset point  164 L, respectively. Right side offset point  164 R and left side offset point  164 L may be 180° out of phase so that as right link member  152 R rises, left link member  152 L falls, and vice versa. Link members  152 R,  152 L may act as pendulums with a top of the pendulums being located at right side offset point  164 R and left side offset point  164 L, respectively. 
     Sprocket  162 R may be coupled to sprocket  166 R by chain  168 R. Left side sprockets may be coupled accordingly. Sprocket  166 R and a corresponding left side sprocket may be coupled to brake/inertia device  118  using belt  120 . Belt  120  may be coupled to an axle or shaft of sprocket  166 R and its corresponding left side sprocket. In some embodiments, devices may be used to operate similarly to sprocket  162 , sprocket  166 , and chain  168 . For example, a pulley and belt system may operate similarly to sprocket  162 , sprocket  166 , and chain  168 . 
     In an embodiment, as a user ascends the exercise apparatus, the user stands on footpads  124 R,  124 L and initiates a walking, striding, or jogging motion. The weight of the user on footpads  124 R,  124 L combined with motion of the footpads and link members  152 R,  152 L may cause a force to be transmitted to sprocket  162 R and its corresponding left side sprocket. This transmitted force may cause rotation of sprocket  162 R and its corresponding left side sprocket. The rotation of sprocket  162 R and its corresponding left side sprocket may cause a rising and falling path of motion of footpads  124 R,  124 L. This rising and falling path of motion may simulate the rising and falling motion of a foot of a user during actual walking, striding, or jogging. The rotation of sprocket  162 R and its corresponding left side sprocket may cause rotation of sprocket  166 R, its corresponding left side sprocket, and brake/inertia device  118 . In certain embodiments, a hip of a majority of users may be positioned near at least a portion of the path of motion of the sprocket  162 R and its corresponding left side sprocket. 
     Right and left link members  152 R,  152 L may be cross coupled using belt  182  and idler pulleys  184 . Right and left link members  152 R,  152 L may be coupled to belt  182  so that the right and left link members move in opposition to each other. Belt  182  may be supported and guided by idler pulleys  184 . 
       FIG. 7  depicts a side view of an embodiment of an exercise apparatus. Link members  190  may be coupled to (e.g., pivotally coupled to) foot members  122 . Link members  190  may be coupled to (e.g., pivotally coupled to) frame  100  at point  130 . Link members  190  may be supported by frame  100  at point  130  and may support an end of foot members  122  coupled to the link members. Foot members  122  may be coupled to link members  152  at a lower pivot point (e.g., a lower end) of the link members. In some embodiments, a lower pivot point of link members  152  may be at another portion of the link members (e.g., a portion near a lower end of the link members). Link members  152  may support an end of foot members  122  opposite from link members  190 . In certain embodiments, link members  152  are members of a pivotal linkage pendulum system (e.g., pendulum members). In certain embodiments, a pivotal linkage pendulum system may include one or more pendulum members (e.g., link members  152 ), foot members (e.g., foot members  122 ), and footpads (e.g., footpads  124 ). A pivotal linkage pendulum system may include left and right portions that are mirror images of each other. In certain embodiments, the left and right portions of a pivotal linkage pendulum system may move in opposition to each other. 
     Link members  152  may be coupled to (e.g., pivotally coupled to) crank members  114  at upper pivot points of the link members (e.g., points  132 ). Link members  152  may act as pendulums with a top of the pendulums being located at points  132 . During use, as crank members  114  rotate, the crank members may displace link members  152 . Crank members  114  may cause right and left link members  152  to move in opposition to each other. Crank members  114  may be coupled to pulley device  116 . Pulley device  116  may be coupled to brake/inertia device  118  by belt  120 . Thus, rotation of pulley device  116  may cause rotation of brake/inertia device  118 . 
     In an embodiment, as a user ascends the exercise apparatus, the user stands on footpads  124  and initiates a walking, striding, or jogging motion. The weight of the user on footpads  124  combined with motion of the footpads and foot members  122  may cause a force to be transmitted to crank members  114  through link members  152 . This transmitted force may cause rotation of crank members  114 , pulley device  116 , and brake/inertia device  118 . As crank members  114 , pulley device  116 , and brake/inertia device  118  rotate, the upper pivot points of link members  152  coupled to the crank members may move in a closed path (e.g., an orbital path approximately represented by arrow  216  in  FIG. 7 ). This closed path motion causes footpads  124  to rise and fall as foot members  122  move forwards and backwards during exercise. The rising and falling path of motion of footpads  124  may simulate the rising and falling motion of a foot of a user during actual walking, striding, or jogging. 
     In certain embodiments, a majority of a path of motion of footpad  124  may be below the closed path of motion of the ends of link members  152  coupled to crank members  114 . In some embodiments, substantially all of a path of motion of footpad  124  may be below the closed path of motion of the ends of link members  152  coupled to crank members  114 . In certain embodiments, a hip of a majority of users may be positioned near at least a portion of the closed path of motion of the upper pivot points of link members  152  coupled to crank members  114 . A user&#39;s foot may follow a path similar to the path shown in  FIG. 5  during exercise. 
     As a user steps downward at a front of a step or stride, a force may be transmitted through the pivotal linkage pendulum system to brake/inertia device  118 . Brake/inertia device  118  may receive and store at least some of this transmitted energy. Brake/inertia device may deliver at least some of the stored energy back to the exercise apparatus to assist in lifting the pivotal linkage pendulum system over the top of a step or a stride. 
     As shown in  FIG. 7 , arm link members  108  may be coupled to link members  190 . In some embodiments, arm link members  108  may be included as a portion of link members  190  (e.g., arm link members  108  and link members  190  are made of a unitary construction). Arm link members  108  may include handles or other devices that may be grasped by a user of the exercise apparatus. 
     In certain embodiments, the right and left portions of a pivotal linkage pendulum system may be cross coupled. Cross coupling may cause the right and left portions to move in opposition. As shown in  FIG. 7 , a cross coupling system may include belt  182 , pulley  186   r , a mirror image pulley on a left side of the exercise apparatus, and idler pulleys  184   u  and  184   l . Idler pulleys  184   u  and  184   l  may be coupled to pulley  186   r  and its mirror image pulley by belt  182 . Pulley  186   r  and its mirror image pulley may be directly attached (e.g., rigidly attached) to link members  190 . Belt  182  may be a continuous belt that causes pulley  186   r  and its mirror image pulley to rotate in direct opposition to one another so that the right and left side portions of the pivotal linkage pendulum system are cross coupled. 
     In certain embodiments, an exercise apparatus (e.g., the exercise apparatus shown in  FIG. 7 ) may be constructed in a compact and economical manner. An exercise apparatus with a pendulum arm (e.g., link member  152 ) that is relatively long compared to a crank member (e.g., crank member  114 ) may allow the placement of a crank system in an elevated position. As shown in  FIG. 7 , crank member  114 , pulley device  116 , belt  120 , and brake/inertia device  118  may be placed in an elevated position. Elevating the crank system may allow for a relatively long user stride compared to a length of the exercise apparatus because the user&#39;s feet may move back and forth into an area below the crank system, as represented by hatched area  191 . A user&#39;s stride length would be shortened if a crank system were placed in a lowered position (e.g., by shortening a length of a pendulum arm (e.g., link member  152 )) so that the crank system inhibits or restricts the user&#39;s stride. A longer stride length may be obtained with a crank system placed in a lowered position, but only by substantially increasing an overall length of the exercise apparatus. Thus, an exercise apparatus with a relatively long pendulum arm compared to a relatively short crank member may allow longer stride lengths to be obtained in a more compact and economical exercise apparatus. 
       FIG. 8  depicts a side view of an embodiment of an exercise apparatus.  FIG. 9  depicts a top view of the embodiment depicted in  FIG. 8 . Foot members  122  may be coupled to link members  152 , link members  190 , link members  192 , and movable members  104 . Foot members  122 , link members  152 , link members  190 , link members  192 , and movable members  104  may be members of a pivotal linkage pendulum system. 
     Link members  152  may be coupled to and supported by movable members  104 . An upper pivot point of link member  152  may be coupled to movable member  104  at point  132 . Link member  152  may act as a pendulum with a top of the pendulum being located at point  132 . In certain embodiments, movable members  104  may be motion generating members. Movable members  104  may be supported by frame  100  at point  130 . Movable members  104  may rotate or pivot about point  130 . 
     Crank members  114  may engage movable members  104  through link members  192  and slider assembly  168 . The crank system (e.g., crank members  114  and pulley device  116 ) may provide at least some support to movable members  104  and the pivotal linkage pendulum system (e.g., link members  152 ) through link members  192 . During use, as crank members  114  rotate, the crank members may displace movable members  104  and cause an end of the movable members to move in a back and forth path of motion centered about point  130 , as approximately represented by arrow  134  in  FIG. 8 . The back and forth path of motion of movable members  104  may cause the upper pivot points of link members  152  to move in a back and forth path of motion. This back and forth path of motion may have at least some vertical component. In certain embodiments, a hip of a majority of users may be positioned near at least a portion of the back and forth path of motion of the upper pivot points of link members  152 . 
     Crank members  114  may cause right and left movable members  104  to move in opposition to each other (i.e., the right movable member moves downwards as the left movable member moves upwards, and vice versa). Crank members  114  may be coupled to pulley device  116 . Pulley device  116  may be coupled to brake/inertia device  118  by belt  120 . Thus, rotation of pulley device  116  may cause rotation of brake/inertia device  118 . 
     In an embodiment, as a user ascends the exercise apparatus, the user stands on footpads  124  and initiates a walking, striding, jogging, or climbing motion. The weight of the user on footpads  124  combined with motion of the footpads and foot members  122  may cause a force to be transmitted to movable members  104 . This transmitted force may cause rotation of crank members  114 , pulley device  116 , and brake/inertia device  118 . As movable members  104  move, footpads  124  may alternately rise and fall. This rising and falling path of motion may simulate the rising and falling motion of a foot of a user during actual walking, striding, jogging, or climbing. A user&#39;s foot may follow a path similar to the path shown in  FIG. 5  during exercise. 
     As a user steps downward at a front of a step or stride, a force may be transmitted through the pivotal linkage pendulum system to brake/inertia device  118 . Brake/inertia device  118  may receive and store at least some of this transmitted energy. Brake/inertia device  118  may deliver at least some of the stored energy back to the exercise apparatus to assist in lifting the pivotal linkage pendulum system over the top of a step or a stride. 
     Arm link members  108  may be coupled to link members  190 . In some embodiments, arm link members  108  may be included as a portion of link members  190  (i.e., arm link members  108  and link members  190  are made of a unitary construction). Arm link members  108  may include handles or other devices that may be grasped by a user of the exercise apparatus. In certain embodiments, arm link members  108  may move in an arcuate pattern during use. 
     In certain embodiments, left and right arm link members  108  may be cross coupled. Cross coupling may cause the right and left portions of the exercise apparatus to move in opposition to each other. Elements  194  may be coupled (e.g., rigidly attached) to arm link members  108  through tubes  196 . Thus, each element  194  may move in unison with each respective arm link member  108  (e.g., the right element  194  may move in unison with the right arm link member  108 ). Connectors  198  may couple each of elements  194  (e.g., the right and left elements) to rocker arm  200 . Connectors  198  may be connector rods. Rocker arm  200  may be pivotally coupled to an upper portion of frame  100  at point  202 . In an embodiment, as arm link members  108  move, connectors  198  may cause rocking motion of rocker arm  200 . This rocking motion may cause the right and left arm link members to move in opposition to each other (i.e., the rocking motion may cross couple the left and right arm link members). 
     During use of the apparatus depicted in  FIGS. 8 and 9 , slider assembly  168  may be located at a fixed position along movable member  104  so that the slider assembly moves along with the movable member at the fixed position. In certain embodiments, slider assembly  168  is movable back and forth (i.e., adjustable) along a length of movable member  104 . The moving of the location of slider assembly  168  along a length of movable member  104  allows the slider assembly to be selectively positioned along the length of the movable member to determine a vertical amplitude of the path of motion of foot members  122  and/or footpads  124 . Thus, adjusting the position of slider assembly  168  allows for varying the vertical amplitude of the path of motion of foot members  122  and/or footpads  124 . Adjusting the position of slider assembly  168  varies the vertical amplitude of the path of motion of foot members  122  and/or footpads  124  by adjusting the geometry of the pivotal linkage pendulum system. For example, a vertical amplitude of a path, such as the path shown in  FIG. 5 , may be adjusted by adjusting a position of slider assembly  168 , thus adjusting the vertical amplitude of the path of motion of foot members  122  and/or footpads  124 . 
     In certain embodiments, movement (e.g., sliding movement) of slider assembly  168  may be controllable. For example, servomotor  170  and lead screw  172  may be used to control the movement of slider assembly  168 . In some embodiments, servomotor  170  and lead screw  172  may be electrically coupled to controller  174 . Controller  174  may be used to control servomotor  170  and to control a position of slider assembly  168 . Controller  174  may include user-operated controls and/or a display for the user of the apparatus. In certain embodiments, a user may adjust a vertical amplitude of the user&#39;s stride by using controller  174  to activate servomotor  170 . Activation of servomotor  170  rotates lead screw  172 , which repositions slider assembly  168  along a length of movable member  104  and adjusts a vertical amplitude of the user&#39;s stride. 
     In certain embodiments, spring  204  may be coupled to slider assembly  168  and link member  192 . Spring  204  may be used to assist in startup of an exercise if crank member  114  is in either a top dead center position or a bottom dead center position. Spring  204  may exert a greater force on one side (e.g., the left side or the right side) of the apparatus to displace crank member  114  slightly off either a top dead center position or a bottom dead center position. 
       FIG. 10  depicts an alternate embodiment of a cross coupling system that may be used in the embodiment depicted in  FIGS. 8 and 9 . Pulley  186   r  and its mirror image pulley may be coupled to idler pulleys  184 F,  184 R with belt  182  so that the pulleys and the idler pulleys work in conjunction with each other. Belt  182  may be a continuous belt that is affixed to pulley  186   r  and its mirror image pulley. Pulley  186   r  and its mirror image pulley may be rigidly coupled to link members  190 . Belt  182  may cause pulley  186   r  and its mirror image pulley to rotate in direct opposition to each other to cross couple the right and the left sides of the pivotal linkage pendulum system. In certain embodiments, idler pulleys  184 F,  184 R may be drive pulleys with overrunning clutches in their hubs. Overrunning clutches may cause unidirectional rotation of shaft  188  when idler pulleys  184 F,  184 R oscillate. In some embodiments, a bi-directional brake may be coupled to idler pulleys  184 F,  184 R so that overrunning clutches are not needed. A bi-directional brake may be, for example, a friction disc brake, a band brake, or an electromechanical brake. 
     In certain embodiments, pulley device  206  may be coupled to shaft  188 . Belt  208  may couple pulley device  206  to brake/inertia device  210 . Brake/inertia device  210  may be a second brake/inertia device on the exercise apparatus. Brake/inertia device  210  may receive and store energy from horizontal motion of foot members  122 . In some embodiments, brake/inertia device  210  may resist horizontal motion of foot members  122 . 
     In some embodiments, arm link members  108  may be coupled to link members  152 , as shown in FIG. I OA. Thus, arm link members  108  may extend a length of link members  152 . The upper pivot point of link members  152  may be coupled to movable member  104  at point  132 . In some embodiments, arm link members  108  may be included as a portion of link members  152  (i.e., arm link members  108  and link members  152  are made of a unitary construction). Arm link members  108  may include handles or other devices that may be grasped by a user of the exercise apparatus. 
       FIGS. 11-17  depict schematic representations of various embodiments of exercise apparatus that may allow motion of a user&#39;s feet similar to motion allowed by the embodiments depicted in  FIGS. 4 , and  6 - 10 . Several embodiments are depicted herein as schematics to simplify discussion of pertinent features. Such depictions may not include one or more features that may be present in a fully functioning exercise apparatus. For example, only the right side foot member, right side footpad, right side movable member, right side link member, right side arm link member, and/or other right side selected components of the apparatus may be shown. In some embodiments, no pulley, belt, and/or brake/inertia system may be shown. In some embodiments, no right and left side cross coupling system may be shown. In some embodiments, one or more members in an apparatus may be straight, may be curved, may be unitary, or may be composed of multiple pieces. 
       FIG. 11  depicts a side view of an embodiment of an exercise apparatus. Slider assembly  168  may be positioned on movable member  104 . Movable member  104  may be coupled to point  130  and extend towards a rear end of frame  100 . In certain embodiments, link member  152  is coupled to movable member  104  at a location between point  130  and slider assembly  168  on the movable member. In some embodiments, link member  152  is coupled to movable member  104  at point  132 , which is at or near slider assembly  168 , as shown in  FIG. 11A . An upper pivot point of link member  152  may be coupled to movable member  104  at point  132 . Link member  152  may act as a pendulum with a top of the pendulum being located at point  132 . The embodiments depicted in  FIGS. 11 and 11A  may operate similarly to the embodiment depicted in  FIGS. 8 and 9 . In the embodiments depicted in  FIGS. 11 and 11A , link member  192  may push movable member  104  upward to lift link member  152  and foot member  122  rather than pulling downwards to lift the link member and the foot member. Movable member  104  may be supported by the crank system through link  192  and slider assembly  168  and supported by the frame at point  130 . Providing support to movable member  104  at these two locations provides structural support both in front of and behind a user that stands on footpad  124 . In such an exercise apparatus, bearings or other coupling components located at, for example, point  130  and/or the coupling between link member  192  and movable member  104  may be subject to lighter loads than found in other embodiments of exercise apparatus in which large loads are placed on couplings in the apparatus. Thus, less expensive bearings or other coupling components may be used for certain exercise apparatus embodiments such as those depicted in  FIGS. 11 and 11A . 
       FIG. 12  depicts a side view of an embodiment of an exercise apparatus. Link member  152  may be coupled to an end of movable member  104 . An upper pivot point of link member  152  may be coupled to movable member  104  at point  132 . Link member  152  may act as a pendulum with a top of the pendulum being located at point  132 . Movable member  104  may be directly attached to crank member  114  at a forward end of the movable member. Movable member  104  may be coupled to support link member  212 . Support link member  212  may be pivotally coupled to frame  100  at point  214 . Support link member  212  may constrain the motion of movable member  104 . In certain embodiments, motion of crank member  114  may cause an end of movable member  104  opposite the coupling to the crank member to move in a closed path (e.g., an orbital path) of motion in space, which is approximately represented by arrow  216 . This closed path of motion may be controlled by a geometry of the crank system, a geometry of the pivotal linkage pendulum system, and/or a position of slider assembly  168  along movable member  104 . In certain embodiments, a majority of a path of motion of footpad  124  may be below this closed path of motion. In some embodiments, substantially all of a path of motion of footpad  124  may be below this closed path of motion. In certain embodiments, a hip of a majority of users may be positioned near at least a portion of the closed path of motion. 
       FIG. 13  depicts a side view of an embodiment of an exercise apparatus. Link member  152  may be coupled to movable member  104  at point  132 . An upper pivot point of link member  152  may be coupled to movable member  104  at point  132 . Link member  152  may act as a pendulum with a top of the pendulum being located at point  132 . Link member  152  may be coupled to and provide at least some support to member  218 . Member  218  may be supported by wheel  220 , which engages the base of frame  100 . A portion of member  218  may move in a back and forth path of motion along frame  100 . In certain embodiments, a hip of a majority of users may be positioned near at least a portion of the back and forth path of motion at point  132 . Member  218  may be pivotally coupled to foot member  122 . Member  218  and wheel  220  may provide at least some support for a user&#39;s weight on foot member  122 . 
       FIG. 14  depicts a side view of an embodiment of an exercise apparatus. Link member  152  may be coupled to movable member  104  at point  132 . An upper pivot point of link member  152  may be coupled to movable member  104  at point  132 . Link member  152  may act as a pendulum with a top of the pendulum being located at point  132 . Movable member  104  may be directly attached to crank member  114  at a forward end of the movable member. Movable member  104  may be supported by and translate along an upper portion of frame  100 . Link member  190  may be coupled to an upper portion of frame  100  at point  130 . Wheel  220  may be coupled to slider assembly  168 . Thus, wheel  220  is coupled to movable member  104  at a position determined by a position of slider assembly  168 . Wheel  220  engages an upper portion of frame  100  to allow movable member  104  to translate along the upper portion of the frame. In certain embodiments, motion of crank member  114  causes an end of movable member  104  opposite the coupling to the crank member to move in a closed path (e.g., an orbital path) of motion in space approximately represented by arrow  216 . This closed path of motion may be controlled by a geometry of the crank system, a geometry of the pivotal linkage pendulum system, and/or a position of slider assembly  168  along movable member  104 . In certain embodiments, a majority of a path of motion of footpad  124  may be below this closed path of motion. In some embodiments, substantially all of a path of motion of footpad  124  may be below this closed path of motion. In certain embodiments, a hip of a majority of users may be positioned near at least a portion of the closed path of motion. 
       FIG. 15  depicts a side view of an embodiment of an exercise apparatus. Member  218  may be coupled to crank member  114  at one end and wheel  220  at another end. Wheel  220  engages the base of frame  100  and support member  218 . Member  218  may be pivotally coupled to link member  152  at point  132 . An upper pivot point of link member  152  may be coupled to member  218  at point  132 . Link member  152  may act as a pendulum with a top of the pendulum being located at point  132 . As crank member  114  rotates, point  132  moves in a closed path (e.g., an orbital path) of motion in space approximately represented by arrow  216 . In certain embodiments, a majority of a path of motion of footpad  124  may be below this closed path of motion. In some embodiments, substantially all of a path of motion of footpad  124  may be below this closed path of motion. In certain embodiments, a hip of a majority of users may be positioned near at least a portion of the closed path of motion. 
       FIG. 16  depicts a side view of an embodiment of an exercise apparatus. Link member  190  may be pivotally coupled to crank member  114  at point  132 . An upper pivot point of link member  190  may be coupled to crank member  114  at point  132 . Link member  190  may act as a pendulum with a top of the pendulum being located at point  132 . Foot member  122  may be pivotally coupled to link member  190  at or near a front end of the foot member. Link member  152  may be pivotally coupled to foot member  122  at point  224 . In certain embodiments, link member  152  is slidably coupled to foot member  122  using slider assembly  168 , as shown in  FIG. 16A . Link member  152  may be coupled to frame  100  at point  130 . An upper pivot point of link member  152  may be coupled to frame  100  at point  130 . Link member  152  may act as a pendulum with a top of the pendulum being located at point  130 . In the embodiments shown in  FIGS. 16 and 16A , as crank member  114  rotates, the crank member causes the front end of foot member  122  to rise and fall. Thus, footpads  124  may rise and fall as crank member  114  rotates. 
       FIG. 17  depicts a side view of an embodiment of an exercise apparatus. Link member  152  may be coupled to movable member  104  at point  132 . An upper pivot point of link member  152  may be coupled to movable member  104  at point  132 . Link member  152  may act as a pendulum with a top of the pendulum being located at point  132 . Link member  152  may be coupled to foot member  122  at or near a rear end of the foot member. Movable member  104 , link member  192 , and the crank system may be located at or near a rear of the exercise apparatus. Movable member  104  may be pivotally coupled to frame  100  at point  226 . Movable member  104  may rotate or pivot about point  226 . The embodiment depicted in  FIG. 17  may operate similarly to the embodiment depicted in  FIGS. 8 and 9 . 
       FIG. 18  depicts a side view of an embodiment of an exercise apparatus. Foot member  122  may be coupled to link member  152 , link member  190 , link member  192 , and movable member  104 . Foot member  122 , link member  152 , link member  190 , link member  192 , and movable member  104  may be members of a pivotal linkage pendulum system. 
     Link member  152  may be supported by movable member  104 . Link member  152  may be coupled to movable member  104  at point  132 . An upper pivot point of link member  152  may be coupled to movable member  104  at point  132 . Link member  152  may act as a pendulum with a top of the pendulum being located at point  132 . Movable member  104  may be an angled member, as shown in  FIG. 18 . Movable member  104  may be coupled to and supported by frame  100  at point  136 . Movable member  104  may be coupled to crank member  114 . During use, as crank member  114  rotates, the crank member may displace movable member  104  and cause an end of the movable member to move in a back and forth motion at point  132 . The back and forth path of motion of movable member  104  at point  132  may cause an upper pivot point of link member  152  to move in a back and forth path of motion. In certain embodiments, a hip of a majority of users may be positioned near at least a portion of the back and forth path of motion. 
       FIG. 19  depicts a side view of an embodiment of an exercise apparatus. Movable member  104  may move up and down a vertical portion of frame  100 . For example, movable member  104  may slidably or rollably engage the vertical portion of frame  100 . Link member  152  may be coupled to movable member  104  at point  132 . An upper pivot point of link member  152  may be coupled to movable member  104  at point  132 . Link member  152  may act as a pendulum with a top of the pendulum being located at point  132 . Movable member  104  may be coupled to crank member  114  through link member  192 . During use, as crank member  114  rotates, the crank member may displace movable member  104  and cause an end of the movable member to move up and down along a vertical portion of frame  100 . The up and down motion of movable member  104  may be a linear back and forth motion approximately represented by arrow  134 . The linear back and forth path of motion of movable member  104  at point  132  may cause an upper pivot point of link member  152  to move in a linear back and forth path of motion. In certain embodiments, a hip of a majority of users may be positioned near at least a portion of the linear back and forth path of motion. 
     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.